will yacht varnish seal plywood

What Varnish to Use on Plywood: The Ultimate Guide

Table of Contents

Plywood can be made of many different types of wood, but the most common is still softwoods. Harder woods are more expensive and they don’t last as long. When you buy plywood at the store, it will come with some sort of sealant on it already; this will keep your new project from getting water damage before you even start building with it! But what varnish should you use on plywood?

Oil-based varnish is a good choice for plywood since it penetrates into the wood giving it a durable and aesthetically-pleasing look.

Types of Varnish

When it comes to choosing a varnish for plywood, there are several options available, each with its unique properties and benefits. Here are the most common types of varnish to consider:

Polyurethane Varnish: Polyurethane varnish is a popular finish known for its enduring strength and resilience to damage. It is proposed in two types, water-based or oil-based styles. Water-bound polyurethane has simple clean-up properties and dries rapidly, perfect for interior applications. Oil-primed polyurethane creates an ultra-sturdy coating that resists scratches and dents well; hence making it ideal for use outdoors. Additionally, this type of coat can impart an inviting natural amber color to the wood’s surface as well.

Spar Varnish: Protect all of your outdoor projects with Spar Varnish. Specifically formulated to shield against sunlight, saltwater, and other extreme conditions, this varnish is ideal for boats, decks, or any project exposed to the elements. Available in both oil-based and water-based formulations; Spar Varnish keeps you covered no matter what Mother Nature throws at you.

Water-Based Varnish: DIY projects are made simpler with this particular type of varnish, which is a top choice due to its ease of use and cleanup. It dries quickly without leaving behind strong odors, making it perfect for indoor applications. Although not as durable as oil-based versions, it may be applied in multiple coats to provide the same degree of protection.

Oil-Based Varnish: For a hard, durable finish that will stand up to wear and tear in high-traffic areas like stairs or floors, oil-based varnish provides an ideal solution. Not only does it protect the wood but also adds a rich amber hue. The tradeoff is its strong fumes and longer drying time than water-based varnishes.

Epoxy Varnish: An epoxy varnish is a two-part system that offers an impervious coating. It’s perfect for outdoor furniture, boats, and any other location exposed to humid conditions. After it dries, this type of varnish will give wood a beautiful glossy finish while preserving its natural beauty at the same time. Plus, you can be sure your surfaces are protected from water and chemicals.

UV-Resistant Varnish: This particular varnish offers a unique level of protection from the sun’s UV rays, thus making it ideal for outdoor applications such as furniture or decks. Whether you prefer water-based or oil-based formulas, this type of varnish will provide your project with an outstanding glossy finish that won’t fade away due to exposure to sunlight.

Uses of Plywood

Plywood is a popular choice of material in construction, woodworking, and crafting. It has a wide range of applications and can be used in many different ways. Here are 8 common uses of plywood:

Furniture making

Plywood is the ideal material for constructing furniture due to its strength and resilience. Whether you’re creating chairs, tables, or bed frames, plywood can be quickly customized to fit any design – making it incredibly versatile! Furthermore, compared with solid wood options, this type of timber is significantly more cost-effective which makes it a great option for budget-conscious buyers.

Cabinetry and millwork

Plywood is an economical way to make your cabinetry, millwork, and built-in storage units look like the real deal. This versatile material can be veneered in practically any wood species, enabling you to work around almost any design aesthetic. Plus, thanks to its cost-effectiveness compared to solid wood, plywood offers a great bang for your buck.

Plywood is the ideal choice for subflooring because of its strength, longevity, and resilience to moisture. With it as your base layer, you can then apply a variety of floor materials such as carpeting, tiling, or hardwood with confidence knowing that your floors will be secure and last for years!

Wall paneling

Plywood is an ideal wall paneling material that can be transformed to suit any room with the right paint or stain. Whether you want a modern, contemporary look or something more rustic and natural, plywood paneling offers endless possibilities to create unique decor for your space.

Roofing and subflooring

Plywood is a popular choice for roofing and subflooring due to its strength, durability, and versatility. It can be easily cut into any size or shape required for installation, making it an ideal material for roof construction. Additionally, plywood’s moisture resistance ensures that it will withstand the elements over time when used as subflooring in both residential and commercial buildings.

Outdoor projects

Plywood is an invaluable material for any outdoor project, from decks and pergolas to sheds. To protect its integrity against moisture damage, it can be treated with water-resistant chemicals, ensuring a long-lasting structure.

Marine applications

Constructing boats and other watercraft requires sturdy, reliable materials like marine-grade plywood that has been designed to be resistant to moisture for a longer-lasting structure. Perfect for withstanding the intense environmental conditions of the ocean, this type of wood provides both durability and reliability when constructing vessels.

Artistic uses

Plywood can be used for artistic and creative projects such as sculptures, murals, and installations. Plywood can be easily cut and shaped to fit any design, making it a versatile material for artists and designers.

RELATED: Top 5 Best Varnish for Plywood: Updated Reviews 2021

Factors to Consider when Choosing Varnish for Plywood

Durability: The strength and longevity of your plywood depend on the varnish you choose. For enhanced protection from daily usage, water exposure, and other environmental elements, polyurethane varnish is often recommended for its enduring effectiveness. When selecting a sealant for your plywood project, opt for a durable option like polyurethane to ensure optimal security against damage over time.

UV-resistance: It is important to pick a varnish with UV-resistant properties if the plywood will be exposed to direct sunlight. This helps ensure that the wood won’t suffer from fading, discoloration, or other damage caused by extended exposure. Spar and epoxy varnishes are well known for their effective UV resistance powers in these cases.

Indoor vs. Outdoor Use: The durability of your plywood’s finish is contingent on which varnish you select. For exterior use, opt for the varnishes formulated to battle unfavorable weather conditions; if it will be mostly indoors, then a standard indoor-grade varnish should suffice. Ultimately, you must carefully consider the intended purpose to determine which type of varnish will provide maximum protection and resilience.

Gloss Level : Choosing the perfect varnish for your plywood should be a reflection of your style. With options ranging from matte to high-gloss, you can find a level of shine that perfectly fits with what you’re looking to achieve. The glossiness or dullness of the finish will depend on which type you select and how it meshes with whatever aesthetic vision you have in mind.

Ease of Application: When it comes to varnish, application ease is a key factor for DIY devotees. While some require specialized tools or experience to utilize, others can be quickly and easily brushed on with a roller or even just your hands! Water-based formulas are particularly renowned for their easy implementation.

Cost: Carefully considering the price is essential when selecting a varnish. Prices range from inexpensive to costly, depending on the quality and longevity of the product. It’s important to find that delicate balance between staying within your budget and still obtaining top-notch durability and performance.

How to Apply Plastic Varnish on Wood in 8 Steps

In case you’ve decided to use plastic varnish on your plywood, here are the steps to follow to ensure a successful application:

Clean and Sand the Surface: Before you begin, ensure the surface is spotless and free of any residue or particles. Gel sandpaper to guarantee that it’s even and polished; then use a moist towel to take off excess dust and allow for adequate drying time afterward.

Apply Wood Conditioner: If your project involves working with porous wood, such as pine or spruce, it is recommended that you use a wood conditioner on the surface. This will promote better adhesion of varnish and avoid blotching. Be sure to read and follow the manufacturer’s instructions for application procedure and drying time before proceeding with subsequent steps.

Stir the Varnish: Before using the varnish, ensure that it is well mixed for an even outcome. Take caution to not incorporate any air bubbles while stirring.

Test the Varnish: Before applying the varnish, make sure to test it on a small and unobtrusive area of the wood to guarantee that its hue is what you desire. If necessary, amend the mixture with either pigment or thinner until your desired outcome is achieved.

Apply the First Coat: When applying the first coat of varnish, use a high-quality brush and be sure to go with the grain. Don’t apply too much in one area as you won’t want any drips or uneven coverage. After completing your work, allow it to dry completely before sanding for an ideal result.

Sand the Surface: Once the first coat has dried, lightly sand the area with fine-grit sandpaper to remove any imperfections and create a smoother surface for the second coat. Wipe away all dust particles using a damp cloth, allowing it time to dry before painting again.

Apply the Second Coat: Following the same application process as with your first coat, apply the second layer of varnish and be mindful of avoiding any drips or uneven coverage. Once done, give it ample time to dry completely before touching it again.

Let the Varnish Dry: Once the second layer has dried, leave your varnish to dry completely by the instructions of its manufacturer. This process should take a few hours or so but may be influenced by temperature and humidity levels.

Varnish to Use on Plywood

When it comes to selecting a varnish to use on plywood, there are a variety of options available. Here are six of the top varnishes to consider:

Minwax Helmsman Spar Urethane: With its remarkable ability to protect against water damage, UV rays, and temperature fluctuations – this waterproof finish is a top-rated pick for outdoor projects. Its crystal clear glossy coat will bring out the natural beauty of your woodwork with no extra effort on your part. Plus it can be used both indoors and outdoors.

Rust-Oleum Marine Coatings Spar Varnish: This varnish is designed specifically for boats and other marine applications, this varnish also makes a great choice for outdoor furniture, doors, and any wood surfaces that need a clear finish to protect them from water and harsh weather conditions. Its superior durability will ensure your wood is safe against the elements while still achieving an attractive appearance.

Varathane Crystal Clear Spar Urethane: In case you’re looking for an exterior solution to protect your doors, windows, and other wood surfaces that are exposed to the elements, our varnish is ideal. Not only will it shield them against UV rays, water, and temperature changes but also bring out their natural beauty due to its crystal-clear finish when dried.

General Finishes Outdoor Oil: This durable penetrating oil provides remarkable protection against water and the elements, making it ideal for both interior and exterior surfaces. Not only does it dry to a matte finish that accentuates your wood’s natural beauty, but applying and maintaining this protective coating is incredibly easy.

Epifanes Clear Varnish: This superior varnish is perfect for marine applications and can be used to seal outdoor furniture, doors, and other wood surfaces. Boasting remarkable UV rays and water protection, this fast-drying formula produces a brilliant clear gloss with every application.

TotalBoat Lust Marine Varnish: This high-performing varnish has been specially formulated to protect boats and other marine vessels from water, UV rays, and temperature fluctuations. Not only does this product provide superior protection but it also leaves a beautiful clear finish that shines brilliantly under the sun’s rays. Best of all, it’s easy to apply and maintain with minimal effort.

Preparation Steps Before Varnishing Plywood

Sanding: To make sure your plywood is prepped and ready for a beautiful varnish, sanding should always be the first step. By using different grits of sandpaper – starting with the coarser kind and then gradually transitioning to finer ones – any roughness or discrepancies will soon disappear. Sanding not only smoothens out the surface but also helps ensure that the varnish adheres well to it to achieve an even finish.

Cleaning: Sanding can leave a mess of dust and dirt; therefore, use a dry, lint-free cloth or tack cloth to remove all traces from the surface. This guarantees that it is clean and primed for varnish application.

Applying Wood Conditioner: Before varnishing your plywood, use a wood conditioner to ensure an even absorption of the finish. Wood conditioner is a pre-stain treatment that brings out the natural grain and creates consistency in application. By applying it before varnishing, you’ll achieve a smoother, more uniform final product.

Filling and Sealing Gaps: Before applying varnish, examine the plywood for any cracks or holes. Utilize wood filler to patch up and level out any gaps or imperfections, then sand it down until smooth. After filling them in, ensure that you cover those crevices with a sealant or finish; this will protect against moisture or air seeping into your plywood’s surface. Give these sealers enough time to dry before moving on to the next step.

How to Apply Varnish on Plywood in 10 Easy Steps

Tools needed.

• Wood conditioner
• Paint roller/brush

Sand the surface of the plywood: To ensure the best outcome, sanding your plywood with sandpaper of at least 120 grit is a must. This will help level out any irregularities on its surface and allow for optimal adhesion of varnish to the wood façade. Sanding also makes sure that no splinters or rough surfaces remain, creating an even and smooth finish for maximum effect.

Clean the surface of the plywood: After sanding the plywood, it is essential to eliminate dust and debris from its surface for a perfect finish. Wipe away any particles with a soft cloth or tack cloth to guarantee that your varnish will adhere properly and provide an even gloss.

Apply wood conditioner: To achieve an even and smooth finish with a softwood plywood, it is advised to apply a wood conditioner before applying varnish. Cover the entire surface of your project using a brush, then let dry completely before layering on the varnish for long-lasting results.

Apply the first coat of varnish: To ensure the best results, use a superior brush to apply your initial layer of varnish on the plywood. Make sure it’s evenly spread out along with the wood grain and create a thin coat; take care not to over-saturate your brush so you don’t have any drips or streaks.

Allow the first coat to dry completely: After the first coating of varnish is finished, give it adequate time to dry before polishing or adding a second layer. Depending on which kind of varnish you use and the specific climate in your space, drying times may vary drastically. For accurate information regarding this process, make sure to read through the manufacturer’s instructions for an exact waiting period recommendation.

Sand the surface lightly: Once your first layer of varnish has dried, use a fine-grit sandpaper to lightly buff the surface. This will eliminate any rough patches and create a sleek finish for the next coat of varnish.

Apply the second coat of varnish: With the second coating of varnish, use the same process as before—by brushing along with the wood grain and ensuring not to overload your brush. Spread it evenly across the surface and give ample time for drying before sanding or continuing onto a third coat.

Allow the second coat to dry completely: Once you’ve completed the second layer of varnish, ensure to wait for it to dry fully before sanding or beginning on a third coat. Do not forget to peruse the manufacturer’s guidebook for their recommended drying period.

Sand the surface lightly: After the second layer of varnish has dried, take a fine-grit sandpaper to tenderly smooth out any bumpy or jagged spots. This will result in an ideally even surface for your last coat of varnish for that perfect finish.

Apply the third coat of varnish: To complete your project, brush on the final layer of varnish by the wood grain and be mindful not to use too much. Make sure it’s applied evenly and then wait until fully dry before utilizing the plywood.

Tips for Applying Varnish on Plywood

When applying varnish on plywood, several tips can help ensure a smooth and successful process. Here are some essential tips to keep in mind:

Use a High-Quality Brush or Roller: Choosing the right brush or roller is essential for achieving a perfect finish. A high-quality tool will guarantee an even application of varnish, leaving no annoying brush marks behind. With this in mind, it becomes apparent that investing in quality can truly make all the difference.

Apply Thin Coats: For a smooth and even finish, varnish should be applied in various thin layers. This will ensure that each layer dries correctly and decreases the chance of any runs, drips, or bubbles occurring. An extra few minutes spent applying several thin coats is much better than rushing to apply one thick coat.

Avoid Overbrushing: Caution must be taken when varnishing to ensure a smooth, even application. An over-brushed surface can create an unsightly bubbled or streaked effect; always apply the product in one direction, avoiding revisiting areas that have already been covered.

Sand Between Coats: For a sensational finish, sanding between coats is essential to smooth out and eliminate any bumps that may have occurred with the prior coat. A 220-grit fine-grit sandpaper should be used for this task, lightly buffing away at the surface before applying another layer of paint or stain.

Maintain Consistent Humidity and Temperature: To ensure a smooth and consistent finish, varnish should be applied in an area with steady humidity and temperature levels as variations can influence the drying time. Varnish is sensitive to changes in these variables which may result in an undesired outcome.

Store Varnish Properly: To extend the shelf life of varnish and keep it in prime condition, proper storage is a must. Store your varnish in a cool, dry place away from direct sunlight or extreme temperatures to guarantee its longevity.

RELATED: Top 8 Best Marine Varnish for Wood- 2021 Buying Guide By A Pro

How many coats of varnish do I need to apply on plywood?

When coating plywood with varnish, the amount of coats you need depends on your goals and the kind of varnish used. Generally, two to three layers are sufficient for most tasks; nevertheless, additional protection can be achieved by applying an extra coat if needed.

Can I use any varnish on plywood?

No, not all varnishes are suitable for use on plywood. It is important to choose a varnish that is specifically formulated for use on wood surfaces, and one that is compatible with plywood.

Should I use a brush or a roller to apply varnish on plywood?

Both brushes and rollers can be used to apply varnish on plywood. However, a high-quality brush is usually the best option for achieving a smooth and even finish. Rollers are more suited for large, flat surfaces, while brushes are better for corners and hard-to-reach areas.

How long does it take for varnish to dry on plywood?

The drying time for varnish on plywood depends on several factors such as the type of varnish used, humidity, and temperature. Generally, most varnishes dry within 24 hours, but it is important to allow ample drying time between coats.

Can I apply varnish on un-sanded plywood?

No, it is not advisable to apply varnish on un-sanded plywood. Sanding the plywood helps to smooth out any rough spots and ensures that the surface is clean and free of debris, allowing the varnish to adhere properly to the plywood.

How often do I need to reapply varnish on plywood?

The frequency of reapplication of varnish on plywood depends on several factors, such as the type of varnish used, the level of exposure to sunlight and weather, and the intended use. In general, it is recommended to reapply varnish on outdoor plywood surfaces every one to three years to maintain its protective properties.

Varnishing plywood can enhance its beauty, durability, and resistance to environmental factors such as moisture, UV rays, and scratches. It is important to choose the right varnish for the intended use of the plywood and to properly prepare the surface before applying the varnish. By following the steps outlined in this guide, anyone can successfully varnish plywood and achieve professional-looking results.

RELATED: Wood Finish Comparison: A Comprehensive Guide To Choosing Wood Finish

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Everything you need to know about Yacht Varnish

Applying Ronseal Trade Yacht Varnish to wooden garden features is a fantastic way of prolonging them. It can be used on all smooth planed exterior wood and offers incredibly tough protection against damage and decay – whilst still highlighting the timber’s natural colour thanks to its clear formula.

The appetite for incorporating natural materials throughout the home and garden is on the up – and as such, we have seen a rise in the number of people interested in garden features such as wooden pergolas, hardwood furniture and rustic wooden details.

When speaking to customers about their ideal garden designs, don’t shy away from incorporating these wooden elements for fear of them warping or decaying in the unpredictable British weather. With the correct preparation, timber can offer the durable and long-lasting finish customers are after.

What is Yacht Varnish?

Yacht Varnish is an incredibly durable solvent-based varnish that was originally used to on boats to protect the wood and prevent it from decaying over time. Nowadays, this type of product is more commonly used for exterior household projects, when you are looking to give timber a high-gloss finish that lasts.

Once applied, Ronseal Trade Yacht Varnish is tough and will protect timber against everyday knocks and scratches as well as harsh weather conditions to prevent cracking, peeling and blistering. What’s more, it is formulated to protect the wood from the damaging effects of the sun and prevent it from discolouring, fading or greying over time. This makes it ideal for features such as wooden pergolas, doors and window frames that are exposed to the elements all year round and ensures that they will last for years to come.

Why choose Ronseal Trade?

Cleverly, Ronseal Trade Yacht Varnish has been formulated to offer the excellent weatherproofing and durability you would expect from a solvent-based varnish but without the long re-coat times. Impressively, it offers around half the re-coat time of a typical solvent-based varnish; it is rainproof in just four hours and it can be re-coated in as little as eight hours. This means that time on site and disruption to the customer can be reduced.

To find out more about Ronseal Trade Yacht Varnish click here .

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How to Seal Marine Grade Plywood

Written by Scott Legros

The many layers of Marine Grade Plywood are held together with waterproof adhesive, allowing the wood to withstand direct contact with water. Since it’s the ideal wood for moist or wet conditions, it’s often used to craft boats, boat parts, or outdoor furniture in coastal areas. By properly sealing this type of wood, you can increase its overall lifespan and make it last for years to come.

Before you get started, gather the following materials:

• Soft cloths or paper towels
• Clear, penetrating epoxy
• Foam brush or roller
• Clean the Surface

Dip a paper towel or soft cloth in acetone and wipe down the surface of the wood to remove grease or other stains. Allow the acetone to dry completely for 1-2 hours before you move on to the next step.

2. Sand the Wood

Like other types of wood, you need to sand marine plywood before you seal, stain, or paint it. Go over both sides of the wood, including edges, with 80-grit sandpaper. Wipe away all dust and particles with a soft cloth.

3. Apply the First Coat

Since marine plywood is typically used underwater, you’ll need to treat every surface of the wood with sealant. We prefer clear, penetrating epoxy because it works its way deep into the wood, dries transparent, and requires less maintenance than other types of sealant. You could use marine-grade sealer, but this will require more coats and must be reapplied every 3 to 4 years.

Dip your foam brush or roller into the sealant. Apply it to the wood, starting with the top and side edges and moving to the front face. Allow the epoxy to dry completely before flipping it over and applying it to the bottom edge and back of the wood.

4. Add Additional Coats

Marine plywood is thicker than typical plywood, so you’ll need to apply more coats to maximize its lifespan. A good rule of thumb is to add as many coats of sealant as there are in the plywood. That means if your plywood has 7 layers of wood, you should add 7 layers of sealant. Gently scuff up the wood with sandpaper between each coat for maximum adhesion, and be sure to wipe off any dust before adding the next layer.

Not sure which kind of wood to use on your next project? At Forest Plywood, we’ve compared marine plywood cost and characteristics to help you choose the perfect type.

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How to Use Yacht Varnish? (A Step-by-Step Guide)

Are you looking for a way to give your boat a polished, professional finish? Yacht varnish provides a layer of protection and a beautiful shine that wont fade over time.

In this step-by-step guide, well explain what yacht varnish is, the benefits of using it, and how you can apply it to your boat.

Well also discuss preparation, application, drying, and sanding between coats, so you can be sure your boat is looking its best.

So, if youre ready to learn how to use yacht varnish, lets get started!.

Table of Contents

Short Answer

Yacht varnish is a protective coating used to seal and protect wood surfaces on boats.

To apply yacht varnish, start by sanding the wood surface with a fine-grit sandpaper.

Then, apply a thin coat of the varnish with a brush, working in long, even strokes.

Allow the varnish to dry for 24 hours before applying a second coat.

Finally, sand the surface with very fine sandpaper before buffing it with a soft cloth.

What is Yacht Varnish?

Yacht varnish is a specialized wood finish designed to protect outdoor wood surfaces from moisture and UV damage.

It typically consists of a blend of resins, oils, and solvents that provide a tough, yet flexible coating, which is ideal for protecting boat decks, outdoor furniture, and other wood surfaces that are exposed to the elements.

Yacht varnish also provides a glossy, attractive finish that enhances the beauty of the wood.

Unlike paint, yacht varnish does not completely cover the wood, allowing the natural grain of the wood to show through.

It is also relatively easy to apply and maintain, making it a popular choice for marine and outdoor wood surfaces.

Benefits of Yacht Varnish

When it comes to protecting outdoor wood surfaces, yacht varnish is an excellent choice.

Not only does it protect the wood from moisture and UV damage, but it also adds a beautiful shine and luster to the wood.

Yacht varnish is a long-lasting coating that can provide years of protection under the right conditions.

It is also easy to apply and can be used on a variety of wood surfaces, including boats, decks, and other outdoor wood surfaces.

When applied correctly, yacht varnish offers many benefits.

It forms a protective barrier against moisture and UV damage, preventing fading, cracking, warping, and other damage that can occur with prolonged exposure to the elements.

The coating also helps keep the wood from rotting, which can be an issue if the wood isn’t properly sealed.

Finally, the varnish adds a beautiful shine and luster to the wood, making it look like new.

Yacht varnish is also easy to apply and can be used on a variety of wood surfaces.

It is a great choice for any outdoor wood surface, including boats, decks, furniture, and more.

It is also relatively inexpensive and can be found at most home improvement stores.

With the right application, yacht varnish can provide years of protection and a beautiful finish to any outdoor wood surface.

Preparing the Wood Surface

Before applying yacht varnish, it is important to properly prepare the wood surface.

The surface should be thoroughly cleaned and dried, and any old varnish should be removed.

Sanding the wood will also help to ensure a smooth, even finish.

It is important to use the correct type of sandpaper for the project.

For instance, a medium-grit sandpaper is suitable for most wood surfaces, while a finer grit may be necessary for surfaces that require a more delicate finish.

Once the surface is prepared, it should be wiped down with a damp cloth to remove any dust or debris.

This will help ensure a successful application of yacht varnish.

Applying the Varnish

When it comes to applying yacht varnish, its important to understand the steps involved in the process.

First, the wood surface should be clean, dry, and sanded.

This ensures that the varnish will adhere properly and will provide maximum protection.

Next, apply a thin coat of varnish with a natural-bristle brush.

This helps to ensure even coverage and minimal brush strokes.

Allow the varnish to dry before applying a second coat.

Its important to allow the varnish to dry completely before applying any additional coats.

Sand lightly between coats to help ensure an even surface.

Additional coats should be applied as needed, but always be sure to allow the varnish to dry completely before exposing the surface to the elements.

With proper application, yacht varnish will protect your outdoor wood surfaces for years to come.

Allowing the Varnish to Dry

When it comes to yacht varnish, it is important to allow the varnish to dry completely before exposing the surface to the elements.

This will ensure that the varnish is properly bonded to the wood and will provide optimal protection from moisture and UV damage.

It is best to allow the varnish to dry for at least 24 hours before applying a second coat.

The drying time will also depend on the temperature and humidity of your environment, so it is important to allow for extra time if these conditions are not ideal.

Once the varnish is dry, it is recommended to lightly sand the surface before applying a second coat.

This will help to ensure that the varnish bonds properly and that the finish is even and smooth.

If additional coats are needed, the process should be repeated.

It is important to allow the varnish to dry completely between each coat, as this will ensure that the varnish fully bonds with the wood.

For best results, allow the varnish to dry for at least 48 hours before exposing the surface to the elements.

By allowing the yacht varnish to dry completely, you can be sure that the wood is properly protected and that the finish will last for years to come.

Sanding between Coats

Sanding between coats is an important step when applying yacht varnish.

After each coat of varnish is applied and has dried, the surface should be lightly sanded to remove any imperfections.

Sanding helps create a smooth, even finish and provides more effective protection against moisture and UV damage.

It also helps ensure that the next coat of varnish adheres properly to the surface.

When sanding between coats, use a fine-grit sandpaper (preferably around 320-400 grit) and sand in the direction of the wood grain.

This helps prevent scratches and other damage to the wood.

Be sure to only sand lightly, as sanding too aggressively can damage the wood and reduce the effectiveness of the varnish.

After sanding, use a clean cloth or brush to remove any dust or debris from the surface.

This will help ensure that the varnish adheres properly and provides the best possible protection.

Once the surface is clean, apply the next coat of varnish as normal.

With proper sanding between coats, yacht varnish will provide effective protection and lasting results.

Applying Additional Coats

Once you have applied the first coat of yacht varnish, it is important to apply additional coats for the best protection.

Depending on the specific product you are using, you may need to apply anywhere from two to seven coats.

It is important to allow the first coat to dry completely before applying any additional coats.

When applying additional coats, it is recommended to lightly sand the surface between each application.

This will help ensure a smooth, even finish and allow the varnish to adhere better.

After sanding, be sure to remove any dust or debris before applying the next coat.

When applying multiple coats of yacht varnish, it is important to use the same type of brush and same technique each time.

This will help ensure a consistent finish.

For example, if you used a natural-bristle brush when applying the first coat, it is recommended to use the same type of brush for subsequent coats.

Additionally, use long, even strokes when applying the varnish.

It is important to note that you should avoid applying too many coats of yacht varnish.

Too many coats can cause the varnish to become too thick and may make the surface appear uneven.

Generally, three to four coats should be more than enough.

Once you have finished applying the desired number of coats, allow the varnish to dry completely before exposing the surface to the elements.

With proper application and care, yacht varnish will help protect your outdoor wood surfaces for years to come.

Final Thoughts

Yacht varnish is a great way to protect your outdoor wood surfaces from moisture and UV damage.

Its important to apply yacht varnish correctly in order to get the best results.

Start by preparing the wood surface, then apply a thin coat with a natural-bristle brush.

Allow the varnish to dry before sanding and applying additional coats as needed.

With proper application, you can enjoy your outdoor wood surfaces for years to come.

Now that you know how to use yacht varnish, why not give it a try on your next project?.

James Frami

At the age of 15, he and four other friends from his neighborhood constructed their first boat. He has been sailing for almost 30 years and has a wealth of knowledge that he wants to share with others.

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How to Waterproof Plywood: 6 Most Effective Methods

Plywood is a great building material, but not every sheet is made equal. If you’ve got standard plywood sheets exposed to water, you need to learn how to waterproof plywood. This will help you avoid costly water damage and repairs down the road.

Waterproofing plywood is a simple process that can save you hundreds in water damage repair costs. You can waterproof plywood using different materials, ranging from waterproof paint to oil and varnish. Doing this extends the life of plywood considerably, preventing rot, warping, and splitting.

In this article, you’ll learn about plywood’s vulnerability to water, the different ways to waterproof plywood, and what types of plywood are available.

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Is Plywood Waterproof?

Can you waterproof plywood, how to seal plywood for outdoor use, how to waterproof plywood, which plywood to choose for outdoor use, types of waterproof plywood.

Plywood is best considered water-resistant, not waterproof. And, even then, “water-resistant” may be too strong a term! Small amounts of water won’t affect it, but prolonged exposure to moisture can be disastrous. Plywood is made of thin wood veneers layered and glued together with pressure and heat. It is a very strong material, but lots of moisture can seep into the layers and cause them to separate or split.

When plywood is being made, the wood is treated with water, which is soaked up and makes the wood expand. Then, when the layers are pressed together and heated, the water is squeezed out, making the wood layers bond together even tighter. For this reason, water and plywood don’t exactly mix.

Plywood is vulnerable to water because it will make the individual wood layers expand again. Over time, this will separate the layers from each other, peeling apart since the glue that holds them together can’t withstand the slow expansion. This can take many years, or just a few months, depending on the amount of water the plywood is exposed to.

What happens to plywood when it gets wet is different than what happens to solid wood. When a wooden beam gets wet, it may soak up water and eventually deteriorate, but it doesn’t lose its integrity easily. Because water separates the layers in plywood, the effects of water damage on plywood are much greater.

Two other things can happen when plywood gets wet, other than splitting: rot and warping. Rot occurs when the moisture so thoroughly corrupts the wood that it cannot hold weight any longer.

In plywood, this can happen in spots where screws/nails are used, and the sheets can come completely loose since the wood no longer holds tight to the nail. Warping results in bent, curved plywood that looks horrible and is useless in any building application.

Plywood is very receptive to waterproofing material. The smooth finish is still porous enough on a micro level that the plywood will easily bond with sealers and paints. This means plywood can still be used outdoors and in marine environments. You can waterproof plywood to use on your outdoor deck, boat dock, or on the boat itself, without worrying!

Waterproofing your plywood is very important because it saves you the headache of completely replacing it every year or two. Since plywood is usually used in entire sheets rather than thin boards, one damaged sheet of plywood affects a large surface area. If parts of your floors and walls are made from plywood, you could end up replacing large parts of your home!

Benefits of sealing Plywood

So, how does waterproofing help? Here are some of the ways that doing a waterproof treatment on your plywood can benefit you:

Prolonged Life

Untreated wood boards, like 2X4’s, last about two years outside. Since it is less moisture-resistant, plywood will likely fail even quicker if left exposed to the elements. The same is true indoors- a water leak is just as deadly to untreated plywood as rain and snow. With properly treated plywood, however, you can expect a lifetime from 20-40 years!

Prevents Rotting

Even if the plywood doesn’t fully split, prolonged water exposure can cause rot just like it would with normal wooden boards. Wood rot doesn’t just look bad- it smells bad, and it drastically weakens the material. Wood rot can spell disaster for your deck, home, or boat. Waterproofing your plywood can save you the headache of dealing with a slowly crumbling plywood panel!

Prevents Dry Rot

Wait, isn’t dry rot the same as normal rotting? While it’s true that the effects of dry and wet rot are similar, they have different causes. Dry rot occurs when microscopic fungi grow on the surface of the wood and is almost impossible to see until it’s too late. It doesn’t require much moisture- the dagame occurs after the wood has dried out and the fungi are already growing!

Protects from Moisture and UV Rays

Repeated exposure to moisture and heat warp plywood quickly. After one rainy summer, a completely flat plywood sheet turns into a modern art sculpture. Those bends and curves might be interesting, but they make for a pretty terrible deck, floor, or siding. Waterproofing plywood sheets is a great way to make sure they last for decades, not months!

Reduces Splitting

Splitting is one of the most damaging results of water exposure in plywood. It causes the wooden layers to separate, completely ruining the sheet. The worst part about splitting is that it can sometimes be hard to see; once you finally notice it, the water is likely damaging other parts of the deck/home/boat already. Make sure to waterproof before installing plywood to avoid splitting!

There are a few common techniques for outdoor plywood sealing. The good news is, most of them are very affordable and relatively simple to put into use. And, with proper application, they’re more or less equally effective. That can make it hard to find the absolute best way to seal plywood because each method does the job rather well.

Let’s take a look at the top 6 methods of waterproofing plywood:

Epoxy Sealer

Using an epoxy sealer is probably the most popular way to seal plywood against the elements. The epoxy is usually found in paint or spray forms . The advantage that epoxy provides is that it makes the plywood stronger, in addition to waterproof. The epoxy forms a tough, hard outer layer that is resistant to scratches and dents as well as water!

The epoxy soaks into the surface of the plywood, and it goes on clear, so wood/plywood retains its natural color. Plus, if you run a bit of sandpaper over the dried epoxy, you can still paint over it, any color you like!

If you’re planning to use plywood in a high-moisture area, like a dock, boat, or you live in a wetter environment, drying oil is going to be the best waterproofing method for you. It works a bit differently from epoxy, paint, and other sealers because it strengthens the wood against water deterioration rather than completely blocking water from the wood.

This means it will dramatically extend the life of the wood without making it 100% “waterproof” in the traditional sense.

Water-Based Paint

However, these problems are easy to fix, and your plywood will be safe from moisture damage with waterproof paint. Plus, most other methods of sealing plywood don’t give you the advantage that paint does: color! Choosing the exact color you need is more than worth the “hassle” of touching up waterproof paint every few years.

It’s not as thick as epoxy or noticeable as paint but has many of the same qualities. Most varnishes will leave an appealing glossy look once dried.

The varnish is ideal for above-water line marine uses; for instance, it’s great for the upper parts of wooden boats or the above-water parts of your dock. As long as it isn’t submerged, it will resist salt, mildew, and moisture for many years. It’s great for outdoor (non-marine use) for that reason as well!

Liquid Latex

On top of that, it isn’t very cost-effective on a large scale. However, you may want to pay the extra price (compared to brushed paint) to have the easiness of spraying liquid latex generously.

If you use it appropriately, as in getting adequate coverage, liquid latex is one method that works just about everywhere. It bonds well to plywood and will last a couple of decades, worry-free.

If you don’t get adequate coverage, water will be able to get into the plywood through the gaps left by poorly sprayed latex, and all your work will be in vain! So, if you choose liquid latex, make sure to completely cover the plywood with a generous amount of spray!

If you want to use PVA to seal plywood, it’s a good idea to dilute it with water so that it will go on thinner and soak into the wood a bit before drying.

Now that we’ve discussed the different available methods of plywood waterproofing, it’s time to do the work of sealing it.

Step 1: Prepare the Plywood

Before the liquid latex, paint, or PVA is applied, the plywood needs to be readied. Clean the surface of the plywood sheet with a brush or dry cloth, removing any dirty spots you can find.

Then, use  wood filler to fill in any rough spots on the surface of the sheet. This will give it a uniform smoothness and help prevent any gaps in the waterproofing. Give the wood filler time to dry and harden before proceeding to the next step.

Once the wood filler dries, wipe down the sheet with a wet cloth. That small amount of moisture will raise the wood’s grain a bit, helping the sealer bond to the plywood sheet.

The final step in preparation is to lightly sand the plywood with medium-grit sandpaper (60-100 grit). This will help smooth the sheet and remove any rough spots that could “gunk” up the painting/sealing.

Step 2: Apply the Sealer

If you’re using a brushed-on sealing method, paint it on with a brush or roller, just as you would normally. Make sure you get adequate coverage and let the first coat dry before applying the second. Some materials and waterproofing needs might lead you to add a third coat. While this might not be necessary, but it can never hurt!

If you’re using a spray method, carefully read the manufacturer’s instructions. Improper use of spray-on sealer results in one of two things:

• not using enough sealer to cover the surface adequately, and
• having a spotty concentration, with lots of sealer in some places and very little in others.

The reason these risks exist is that spray-on sealers are harder to see and control than brushed-on sealers. So, when you spray the sealer, be very intentional with where you are pointing the can!

Step 3: Let it Dry, and Keep an Eye

Give the plywood at least a few hours to dry, up to 24 hours if you have the time to spare. Then, once it’s completely dry, you’re free to install it! After plywood is installed, add a bit of sealer over the screws/nails to ensure it stays watertight!

Finally, although your plywood sheets are now waterproofed, you should still check them out every few months to make sure water isn’t wreaking havoc without your knowledge. Water damage will be easy to spot, so this shouldn’t feel like a comprehensive inspection- just an “eyeball test” to ensure all is well!

How to Seal Plywood Edges

We’ve gone over how to seal the surface of a plywood sheet, but what about the edges? Should they be waterproofed, and if so, how do you seal plywood edges? Because plywood is made of several layers, the edges are particularly vulnerable to water.

When water is introduced to plywood edges, it can split much faster than it would on the sheet’s surface. So, it’s very important to waterproof the edges- perhaps more important than surfaces!

Sealing plywood edges is relatively simple; apply several coats of varnish, allowing each coat to dry for about an hour. The edges will soak up the varnish quickly, so you need more coats to make sure it dries to form that protective layer.

It would be a mistake to assume that all plywood is the same and equally vulnerable to water damage. The reality is that plywood is a diverse category of wood products, and each type of plywood is better for a specific application. Some plywood is pre-treated for waterproofing before you buy it, so you don’t even have to worry about sealing it yourself!

Two types of plywood are the best for outdoor use: CDX Plywood and ABX or “marine-grade” plywood. CDX is made of rough, lower-quality wood that is heavily treated for water resistance and is ideal for things like roof sheathing.

Marine-grade plywood is much smoother and higher quality and has the best waterproofing of any plywood. As the name implies, marine-grade plywood is designed for decks, boardwalks, and other waterfront construction.

Plywood is graded on an A-D system; A is the highest and D is the lowest. The first letter represents the front face, and the second letter represents the back face and is usually more coarse.

The third letter is less important but signifies the type of glue used to bond the layers. These letters represent the appearance of the wood, not the strength it has. So, ABX looks much nicer than CDX, but they both have similar strength and water resistance. Let’s take a look at the different types of waterproof plywood and their recommended uses!

ABX Plywood

ABX, also known as marine-grade plywood, is a smooth, strong plywood. It’s intended for marine use, but it can also make great exterior plywood anywhere. It is specially treated to be resistant to salt and mildew along with water, and has the smoothest, most appealing surface of any plywood, hence the “AB” grade.

ACX Plywood

ACX is waterproof plywood that has much in common with marine-grade sheets but doesn’t have the marine-specific treatment. It is waterproof, tough, and perfect for use in decks, exterior walls, and renovations.

ADX Plywood

This type of plywood is pretty much the same as ACX, but the back face of the sheet is of the rougher, knottier variety. It can be a cheaper option because only the front face is the pricier “A” graded veneer. It’s great to use in exterior construction or as a subfloor in a home.

BWP Plywood

The letters in this plywood stand for “Boiling Water Proof”- and it’s exactly what it sounds like. This is extremely durable plywood and will keep its integrity even in the face of boiling water! It’s ideal to use when you are constructing a kitchen or bathroom where hot water and steam will be ever-present.

MR Grade Plywood

The “MR” stands for “moisture resistant” and is good indoor-use plywood. It isn’t completely waterproof- it resists moisture and water droplets but will falter against standing water. In humid climates, MR plywood is ideal for interiors because it won’t warp from humidity.

BWR Grade Plywood

“Boiling Water Resistant” plywood is like the slightly weaker cousin of BWR plywood. It will hold up well against steam and boiling water, although it is not technically watertight. It’s best used in places where water and steam might be present but not all the time- cabinets, sinks, etc. are all great places to use BWR grade plywood.

Finding a way to seal and waterproof plywood is very important to the longevity of your home, deck, or shed. It’s a relatively simple process, and with a bit of care, anyone can make plywood completely waterproof with a few easy steps! And, if you choose your plywood correctly, you may never even need to waterproof it yourself because several types of plywood are waterproof or water-resistant.

Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. He is passionately interested in home improvement, renovation and woodworking.

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What’s the Best Varnish for Your Yacht?

Varnishing your yacht is an essential part of its care and maintenance. The benefits are twofold: yacht varnish protects your boat from the elements, while also giving it a beautiful shiny finish. But with so many different yacht and marine varnishes to choose from, it can be difficult to know which one is best for your boat. In this article, we’ll run through some of the most popular types of yacht varnish on the market to help you choose the right option.

What is Yacht Varnish?

Yacht varnish is an extremely durable solvent-based coating that is designed to protect the wood that yachts are made of and stop it decaying over time. Most varnishes are made up of a penetrating oil, resin and solvent. Although most yacht varnish is applied with a brush, it is possible to buy yacht varnish spray.

Different Types of Yacht Varnish Finish

There are many different types of finish to choose from, so you’ll need to know a little about them to decide which is the best yacht varnish for you.

• Clear Yacht Varnish. A clear yacht varnish does what it says on the tin: it will create a transparent, glossy finish that does not alter the colour of the wood it is applied to.
• Matt Yacht Varnish. Using a matt coloured yacht varnish will result in a dull, non-shiny finish that does not reflect light. This can be ideal for hiding flaws or imperfections in wood.
• Yacht Varnish Satin. A satin varnish falls between clear and matt. This type of finish will create a pearl-like sheen, without being overly shiny or reflective.

Designed by Freepik https://www.freepik.com/

Yacht Varnish Brands

There are various brands that produce yacht varnish. Here are a couple of the most popular:

Screwfix Yacht Varnish

Screwfix is a retailer in the UK that sells a variety of products, including hardware and building supplies. They may carry different brands and types of yacht varnish. Yacht varnish provides resistance to water, UV rays, and other environmental elements. Yacht varnishes often contain additives to enhance their durability and performance in marine conditions.

Ronseal Yacht Varnish

A durable, long-lasting marine varnish for wood that flexes with the movement of the wood and resists peeling and cracking. This varnish is slightly more pricey than the Screwfix varnish, but gets great reviews. You can buy the Ronseal brand of yacht varnish in B&Q and other retailers.

How to Varnish Your Yacht

Varnishing a yacht is fairly straightforward, if a little time-consuming. First you’ll need to carefully sand down the entire surface that you want to varnish to get it looking smooth. Then use a soft brush to wipe off any excess dust and debris, since you don’t want it getting trapped in the varnish.

Finally, use a paintbrush to coat the yacht with varnish. Leave it to dry for the recommended amount of time on the tin, then apply additional coats as required. Always check the instructions of your varnish type, and if unsure consult with an expert before starting.

• How long does it take for yacht varnish to dry? Yacht varnish generally takes 4 – 6 hours to dry, although you should check the instructions for the specific product you’re using. You’ll probably want to do two or three coats of varnish, leaving sufficient drying time in between coats.
• Is yacht varnish good for decking? This depends on the product you choose. Some yacht varnish is suitable for decking, while others are not because they do not have an anti-slip formula.
• Is yacht varnish good for floors? Yacht varnish should not be used as an indoor floor varnish. It is difficult to dry indoors, and contains chemicals that can be toxic if it is not used correctly.
• Is yacht varnish safe for animals? Yacht varnish is solvent-based and contains toxic chemicals, which means it should not be used for varnishing animal enclosures (for example, rabbit hutches or reptile enclosures).
• What is yacht varnish used for? Yacht varnish is used for sealing and protecting wood on boats and yachts. It is also commonly used for outdoor items such as wooden doors, window frames or pergolas.
• What type of varnish is yacht varnish? Yacht varnish is a solvent-based outdoor varnish that is extremely durable. It is usually made up of tung oil and polyurethane resin. 
• What is the best varnish to use on a boat? The type of varnish that is best for your boat will depend on the type of wood your boat is made from and the finish you are looking for. Tung oil varnish is a safe bet for most boats, or you may prefer to use a one-part polyurethane varnish for added durability.
• What is the difference between yacht varnish and outdoor varnish? In general, yacht varnish dries quicker and is designed for marine conditions, so it’s likely to be more durable than outdoor varnish. However, yacht varnish is unlikely to have an anti-slip formulation, making it unsuitable for decking around the home.

Looking for yacht and boat insurance ? Buy your sailing yacht insurance online at Admiral, or contact our expert team for advice.

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Varnish options

• Thread starter Kelpie
• Start date 4 Nov 2018

Well-known member

I used several coats of International Goldspar Satin on the sole boards 12 years ago and they're still OK 12 years later despite up to 8 months aboard each year, although shoes rarely worn. Did the apartment wood block floor with water based (foreign brand) 3 years ago and that's still fine and I would use it on any interior boat woodwork, can overcoat in a couple of hours in warm climate if not sanding between coats. Exterior, I use Woodskin on cockpit table and grab rails and quite happy with results. Sounds like you may have Burgess Woodseal now, that needs stripping off before applying varnish.  

Lightwave395

Am I reading this correctly - you really have wooden spreaders...?  

Cant comment on the outside , but I used a polyurethane varnish for the inside , sanded all down the teak , and mixed 75% white spirit with 25% varnish for first coat , this helps tie the varnish, 2nd coat 50% 50% 3 coat 100% varnish A lot of hard work but the results are nice Good luck  

Lightwave395 said: Am I reading this correctly - you really have wooden spreaders...? Click to expand...

Graham376 said: I used several coats of International Goldspar Satin on the sole boards 12 years ago and they're still OK 12 years later despite up to 8 months aboard each year, although shoes rarely worn. Did the apartment wood block floor with water based (foreign brand) 3 years ago and that's still fine and I would use it on any interior boat woodwork, can overcoat in a couple of hours in warm climate if not sanding between coats. Exterior, I use Woodskin on cockpit table and grab rails and quite happy with results. Sounds like you may have Burgess Woodseal now, that needs stripping off before applying varnish. Click to expand...

LeTonkinois is a fantastic varnish. Get 6 seasons out of it.  

For interior use, we have been using the water based Ronseal and it seems to work fine. Someone on this forum gave a very good piece of advice with it - if you want a silk or matt finish, put a coat or two of gloss on first and finish off with one coat of the silk or matt in the same colour. You really need multiple coats to develop enough protection, but multiple coats of silk or matt tend to end up looking a bit cloudy - obscuring the grain.  

Hmmm, I'm starting to wish I had used Le Tonkinois instead of Woodskin on my toe-rails etc. From what I've read it appears to have similar ease of use and touch-up, but looks better- more like proper varnish.  

Kelpie said: Hmmm, I'm starting to wish I had used Le Tonkinois instead of Woodskin on my toe-rails etc. From what I've read it appears to have similar ease of use and touch-up, but looks better- more like proper varnish. Click to expand...

I have tried a few finishes on my toe rail and currently find Woodskin the most efficient. It is an area which takes knocks, foot traffic and rope abrasion, so do not expect too much of any solution, which makes Woodskin (at least for me) appropriate. 3 coats does a couple of years looking reasonably good, but its big advantage is the ease by which it can be prepped up for a re-fresh. I use Le Tonk on things like hatchway surround and bits of trim )lovely stuff!), polyurathane varnish or Epiphanes on the bowsprit and either Epiphanes black or international Goldspar satin down below. The main hatch boards are epoxy coated with polyurathane or Epiphanes on top - and this is the most stable/durable varnishwork topsides.  

Look at Coelan, its a liquid plastic with 15% elasticity. I used it on the varnished parts of my boat in Greece and 6 years later it was as good as new, just needed regular wipes with a damp cloth. Provided you follow the instructions, it's an easy fix. Albeit upfront cost is higher than varnish, offset against another 5 years of lounging instead of varnishing!!  

PS I also recall one of the yachting mags did a long term test of yacht varnishes and Coelan was the product with best result.  

Poignard said: A very good book on all aspects of varnishing is: " Brightwork: the Art of Finishing Wood" by Rebecca Wittman https://www.amazon.co.uk/Brightwork-Finishing-Wood-Rebecca-Wittman/dp/0071579818 So happens I have a copy to sell at £10 plus p&p. I also have some unused tins of Le Tonkinois. Click to expand...

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How Do You Seal Marine Plywood – 3 Easy Steps

Because of its durability and resistance to the elements, marine plywood enjoys a strong reputation.

However, because this type of plywood has not been subject to chemical treatment, it can over time become damaged by precipitation and ultraviolet rays from the sun.

So, the question becomes whether you should take the step to seal the plywood.

The answer is yes. You will need to seal the plywood despite the fact that it is strong, durable, and long-lasting.

This is because without being sealed, the moisture will get inside and do damage.

To protect its durability, you will need to seal the plywood to maintain its strength and color. Plus, it will prevent rot from setting in.

What's Covered in the Article:

Steps to Sealing Marine Plywood

Sealing your plywood is important if you are using it for constructing something that will need to be submerged in water.

To get started, you will need the following products.

• Acetone, Sanding Block, and Paper Towels
• Foam Roller, Sandpaper, and Paint Basin
• Foam Brush, Clean Cloth or Rag, and Sealer

Step One: Clean & Sand

Put a little acetone on the cloth and clean the plywood. The acetone will remove the grease and unwanted stains from the surface.

Once you have cleaned the plywood, let it dry for one to two hours.

Next, use fine-grit sandpaper and sand the entire surface along with the edges of the plywood.  

Good surface preparation is key to getting a smooth finish on the plywood, so do it carefully.

If you have a sander, you can use that to make the process go faster. Be sure to sweep or vacuum up the sawdust from the wood once completed.

Step Two: Apply the Sealant

You will be using an epoxy resin moisture sealer for this step along with the paint basin.

Dip the foam roller into the paint basin which contains the sealer. Then brush the roller against the sides of the basin to remove any excess sealer.

Next, roll the sealer onto small sections of the plywood, such as 2’ x 2’. This will make sure the sealer does not dry too quickly.

Go one section at a time horizontally until all the plywood is covered with a thin coat.

If you want to avoid having brush marks on the plywood, drag a foam-tipped brush over the sealer before it dries.

Step Three: Let It Dry & Reapply

It takes from one to two hours for the sealant to fully dry.

Once it does, add a second coat which you can apply vertically to the plywood.

Let that dry and if you feel that a third or four coats are necessary, then you can keep applying them as long as you want.

Generally speaking, four coats of sealer will be enough to protect the plywood beneath the water surface – if you are using it underwater.

Also, remember to seal and treat the plywood from both sides to get good long-lasting results.

Should you seal the plywood for interior use?

Sealing the plywood isn’t essential if it’s used in dry rooms like bedrooms and dining rooms.

But if you are using it in areas like bathrooms and kitchens, it’s better to seal and waterproof the plywood.

What Is Marine-Grade Plywood?

This is a special type of plywood that uses Western Larch or Douglas fir.

In simple terms, it’s a specific variety of plywood that’s been pre-treated to withstand moisture.

The term marine plywood or marine-grade plywood does trick many people into believing that it is waterproof.

And while it does use waterproof glue to hold the particles together, it inst completely waterproof. Also, it lacks the chemical treatment that would have the plywood resist rot and decay over time.

There are four grades of marine plywood with the higher grades being quite strong with no defects and lightweight for easy handling.

This is why you see marine plywood used in so many different projects, especially the construction of boats and doors.

Also, for long-term projects such as lining the interiors of boats, boat floors, doors for coastline homes, and so forth.

Being naturally strong also makes this type of plywood an excellent choice for use in changing conditions such as when exposed to winds or the elements.

This is why you often see marine plywood is also used for temporary projects such as sealing windows when strong storms or hurricanes are expected.

But if you want it to last, you will need to seal it from the elements. 

How Long Does a Marine Grade Plywood Last?

Marine plywood is quite strong and durable, especially when it is sealed from moisture and other elements.

Depending on the overall quality and how the plywood is used, you can expect it to last from ten to twenty-five years.

However, keep in mind that knowing what factors will apply and how you use the plywood will affect how long it lasts, so you will need to educate yourself on this subject.

• Exposure to Moisture
• If a Sealant or Chemical Treatment is Used

This will help you decide the grade of marine plywood that is best for the job.

This may mean that a lower quality marine plywood might work as well as a higher quality one depending on the circumstances in which it is used.

In other words, you may be able to save a considerable amount of money by purchasing the right grade of plywood for your project.

Marine plywood comes in four grades, A, B, C, and D. The higher the grade, the stronger and longer-lasting the plywood.

Depending on its use, A D-grade marine plywood may be just as suitable as an A-grade.

Of course, the supplier plays a role in the quality of the marine plywood as well, so be sure to get your plywood from a trusted source.

And inspect the plywood for any damage such as cracks or large imperfections so you do not purchase them.

Moisture exposure:

Although UV rays can take their toll, it is the exposure to moisture that is the biggest single factor in the grade of marine plywood that you choose.

Marine plywood itself is strong and durable with a reputation for lasting a long time even when exposed to moisture.

However, if you want the plywood to last for decades, then it will need to be sealed depending on the environment.

The greater the amount of moisture, the more likely the plywood is to break down over time.

This means that plywood used on a boat is going to break down faster compared to plywood used inside your home.

You can expect marine plywood used on a boat dock to last up to twenty years with the proper care.

While marine plywood used for interior flooring may last thirty years or longer depending on the care you provide.

If you are not sure of the moisture levels, then you can use a moisture meter to determine how much is present.

This will help you make the best-informed decision about which grade of marine plywood to use.

Chemical treatments:

Even lesser quality plywood can hold up to high moisture levels if it is properly sealed or chemically treated.

Most plywood types do not have the strength or quality, to hold up long in a moist environment without warping or rotting relatively quickly.

Marine plywood is different which is why you often see it used on boats and along the shoreline.

But it is not impervious to moisture. You will need to use a good wood sealer if you want it to last in such environments.

Regardless, marine plywood is an excellent choice for moist environments.

And an even better choice for dry environments where you want the plywood to last for a long time.

Can You Paint Marine Plywood – Rather than Sealing?

Whether it’s for home exteriors or for marine purposes, marine plywood should be sealed in order to be fully durable.

However, if sealing with epoxy seems to be tough, you can simply paint your marine plywood properly to enjoy similar benefits.

Here are some know-hows you need to check…

• Before applying any paint, sand the surface to remove any imperfections in the wood.
• Prime the surface with a thin coat of latex-based primer. Allow it to dry and sand the surface lightly again.
• Now using semi-gloss latex-based paint cover the marine plywood surface evenly with a paint roller or a brush.

For achieving the right finish and protection applying at least two thin coats of paint is recommended.

An additional third coat can be applied for greater protection if you desire.

Sanding between paint coats is not essential, but you should allow enough time to dry the surface between two successive coats.

The Bottom Line

Marine plywood has earned a solid reputation for its durability and longevity in moisture-rich environments along the coast.

This is why it is often the first choice of plywood for many different projects where moisture is present.

It is also lightweight which makes it easy to handle.

But even with its natural resistance to moisture, marine plywood will still need to be sealed.

So, if you are using it for a long-term project in a moisture-rich environment, be sure to take the time and properly seal it so that it will last.

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Beginners Guide To Plywood Sealer (What You Need To Know)

Plywood is so strong and durable that it’s easy to forget that this manufactured wood needs extra help to protect it from the elements.

And sealing plywood is one of the best ways to guard this multi-layered lumber from rot, bugs and insects.

So, what is the best plywood waterproof sealer?

If you want to waterproof plywood, then coat it with a quality liquid latex sealer. The sealer protects by wrapping plywood in a plastic water-resistant covering. However, you can give plywood even better water-proofing by sealing it with Aquarium sealant. Aquarium sealant is a silicon sealer that is regularly used on marine ships, aquariums, vivariums, and outdoor plumbing.

Still, plywood can be a bit tricky to seal up properly. This is especially the case when you consider how easy those exposed ply edges make it for water to seep in.

So lets take a further look at what you need to know before you start work on waterproofing your plywood project…

This post may contain affiliate links to products that we receive a commission for (at no additional cost to you). Learn more here.

Can Plywood Be Waterproofed?

First of all, yes, plywood is relatively easy to seal and waterproof. Plus, it is a reasonably moisture resistant manufactured wood to boot.

Why is that? Well, all of those ply layers are glued together using a water resistant adhesive that is great at repelling moisture.

Do You Have To Seal Plywood?

Yes, because plain plywood board is not rot-resistant.

You see, in order to make wood rot-resistant, we put it through a process called ‘pressure treatment’. This process involves putting lumber into a tank and immersing it in a chemical treatment.

Those chemicals then infuse deep into the grain, making the wood resistant to rot and burrowing insects.

Now, thanks to plywoods layered-nature, chemical treatments never quite manage to fully penetrate the veneers at the very center of the plywood sheet.

So if you plan on installing plywood in an area that’s likely to have a lot of water splashback (like, say, a kitchen countertop) you should use an exterior-graded plywood.

Thanks to waterproof glue, exterior-grade plywood can handle water and humidity better than standard ply sheets.

You can learn more about using plywood for kitchen countertops in our post MDF Or Plywood For Countertops: Which One’s Better For Your Kitchen?

Is Pressure Treated Plywood Waterproof?

While we do still put plywood through the pressure treatment process, it is more of a ‘surface-level’ treatment. This is because the treatment only manages to penetrate the outermost layers and edges of the plywood.

As a result, even pressure treated plywood needs to be carefully sealed and fully water-proofed all over, (if you want to prevent it from rotting).

How Long Will Untreated Plywood Last Outside?

If you had a piece of untreated and unsealed plywood, and you used it on an outdoor structure, it would last about 2 years.

Between the wind, rain and sunlight exposure, the ply would start to rot away within one year. And it would completely keel over by the end of year two!

Should You Always Seal Plywood Before Painting?

You should always take the time to seal plywood before you add a coat of paint.

While you can paint directly onto plywood, paint isn’t enough to wrap the sheet in a completely water-tight seal.

In fact, if you apply paint onto plywood without sealing first, then water will easily seep through the paint . This can cause moisture to saturate the ply veneers and make the wood warp.

So, How Do You Protect Plywood From Water?

The answer to this is very simple… you coat it with a waterproof substance that ‘seals’ the plywood in.

Liquid latex sealers are always a popular sealant choice. So lets have a look at some of the most popular sealers on the market;

Can You Use Thompson Water Seal On Plywood?

One of the best weatherproofing sealers available is Thompson’s WaterSeal.

Simply put, yes, you can use this brand of sealer on plywood. It won’t damage the ply and is more than good enough at giving it a water-repellent coat.

Check out the latest prices for Thompson’s WaterSeal over on Amazon.

Can You Use Flex Seal On Plywood?

Well, first off, I’ll have to admit that Flex Seal is a pretty convenient way to seal almost anything.

This aerosol sealant lets you easily spray liquid latex onto wood. Which can save you a lot of time if you compare it to applying the sealer using a brush.

Also, it is very useful as it makes quick work at giving the entire plywood sheet an even coat. Plus those latex spray droplets can easily get right into those wood pores.

And since you can use it to seal most any type of surface material – including piping, plastic, and even porcelain – plywood is not a problem for Flex Seal.

Now, having said all of that, Flex Seal is not the best sealer on the market.

While it may be water resistant, it is not water tight. And that is a real cause for concern if a piece of plywood is going to be exposed to outdoor weather (such as humidity and rain).

So, to cut to the chase, don’t use Flex Seal on Plywood. Why? Well, to be frank, there are much, much better wood sealers available on the market.

For example, Spar Urethane is a much better option for sealing exterior plywood.

Its water-resistance and mold-proofing makes Spar Urethane the go-to option for sealing garden furniture and boat decking. Discover more about applying Spar Urethane to plywood in our post Can Spar Urethane On Plywood Weatherproof It?

What Is A Good Plywood End Grain Sealer?

Now, just using latex sealer is typically not enough to seal up plywood end grain. This is because all those ‘voids’ along the sheets side can prove to be a problem.

Not sure what plywood voids are? Have a look at the picture below. Those big gaps in the side of the wood are what we refer to as ‘Plywood Voids’:

Instead, you have to fill in those plywood edge gaps before you coat on the sealer. In which case, you should apply a clear epoxy coat first, and pack out those gaps.

The best epoxy filler coat for plywood has got to be Abatron WoodEpox Epoxy.

Check out the latest prices for this epoxy wood replacement compound over here on Amazon.

Can You Seal Plywood With PVA?

PVA (Polyvinyl Acetate) is a water-based emulsion adhesive that is regularly used to glue everything from boxes to books.

This is the same glue you would find in both school glue (for sticking paper together) to carpenter glue (like ‘Elmer’s Glue).

When used as wood glue, PVA is very water resistant and can hold joints in place incredibly well.

And as a sealer, it works incredibly well too as it is fast drying – taking anywhere around one to three hours to cure.

However, if you are going to use PVA, you probably need to water it down to thin it out a bit first before using it to seal plywood.

Ideally, you would only use PVA more as an end grain sealer, rather than use it to seal the face grain of the plywood sheet. But whether you choose to seal end grain with epoxy or PVA comes down to personal preference.

When Should You Consider Using A Silicone Sealer?

Some liquid latex sealers, (even after they’ve cured and dried), can still give off harmful VOC levels. And those gases can prove dangerous to some pets.

What does VOC mean? VOC refers to ‘Volatile Organic Compounds’. And VOC levels measure the amount of strong fumes released into the air off of products such as sealants, paints, and varnish.

So, alternatively, you can seal plywood with a non-toxic silicone sealer.

This is especially important if you plan on sealing plywood that will be used to build a reptile vivarium.

In these instances, you should always use a 100% silicone sealer – such as Aqueon Silicone Sealant. Otherwise those VOC fumes could hurt your bearded dragon, turtle, or pet snake.

Check out the latest prices for this silicone sealer here on Amazon.

Final Thoughts

Waterproofing plywood is key to making sure that repurposed lumber lasts a long time. It is also the best way to prevent cabinets from warping , or structural plywood sheathing from rotting away. Just remember;

• Liquid latex sealants are great at waterproofing plywood.
• But, make sure you fill in plywood end grain gaps with epoxy first before sealing it over.
• And if you are sealing a plywood Aquarium or Vivarium, use a non-toxic pet-safe 100% silicone sealant instead.

https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality

https://en.wikipedia.org/wiki/Polyvinyl_acetate

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How to Waterproof Plywood for Boat

Plywood is a popular material for building boats but is not naturally waterproof. If you’re building a boat with plywood, protecting it from moisture is vital to maintain its structural integrity.

Finding the best way to waterproof plywood for your boat can seem daunting, but it’s essential if you want to extend your boat’s durability and life. In this post, we’ll discuss several effective methods on how to waterproof plywood for boat to keep it safe from water damage.

Can You Waterproof Plywood for A Boat?

Owning a boat is a great way to explore the beauty of the open water. However, with great ownership comes great responsibility. To keep your boat in the best possible condition, it is important to ensure that it is protected from natural elements. When protecting your boat, one of the most important things you should consider is waterproofing the plywood. 

The good news is that with the right knowledge and equipment, waterproofing plywood for a boat is possible. So, whether you want to protect your boat from water damage or improve its durability, waterproofing your plywood is a task you should add to your to-do list.

Why Should You Waterproof Plywood for A Boat?

When building a boat, using the right materials and taking the necessary steps to ensure it remains functional for years is crucial. One key element in boatbuilding is using plywood. However, if left unprotected, plywood can quickly deteriorate and become damaged by water, leading to an unsafe and unreliable vessel. 

That’s where waterproofing comes in. By waterproofing your boat’s plywood, you can safeguard it against water damage, warping, and rotting, ultimately increasing your boat’s longevity and performance. So, the next time you build or restore a boat, don’t overlook the importance of waterproofing plywood. Your boat (and wallet) will thank you in the long run.

How to Waterproof Plywood for Boat: A Complete Guide

1. Use Marine-Grade Plywood

If you’re using plywood in building your boat, make sure to use marine-grade plywood designed specifically for boat construction. Marine plywood uses a waterproof glue that holds the layers of wood together.

It has no voids, which means that there are no gaps between the wood layers that could cause water intrusion, weakening the boat’s structure. Marine plywood is the best choice for boat builders who want to avoid the risk of water damage.

2. Seal the Edges with Epoxy

The edges of plywood sheets are the most exposed areas for water damage. One of the effective ways to protect the edges is by applying epoxy resin. Epoxy is a durable waterproof coating that creates a protective barrier against moisture.

Before applying epoxy, it’s important to prepare the wood surface by sanding it to remove dirt or debris. After that, apply a thin layer of epoxy on the edges of the wood and let it dry completely before moving on to the other side.

3. Apply Fiberglass Cloth

Fiberglass cloth is another waterproofing method boat builders use to protect their plywood boats. The cloth reinforces the boat’s structure while creating a strong barrier against water penetration.

Before applying fiberglass cloth, sand the wood surface to make it smooth. Then, apply a coat of epoxy to the wood and lay the fiberglass cloth on top of it. Use a squeegee to smooth out any air bubbles. After that, apply a topcoat of epoxy resin to seal the fiberglass cloth completely.

4. Apply Marine Paint

Marine paints are specialized paints designed to withstand harsh maritime environments. They are an affordable and straightforward option for waterproofing plywood boats. When using marine paint, it’s essential to sand the wood surface first to allow the paint to adhere to the surface properly.

Apply multiple layers of paint, letting each layer dry before applying the next. Make sure to apply the paint to the edges and any other exposed areas, such as the bottom of the boat.

5. Use Elastomeric Marine Sealant

Using elastomeric marine sealant is another effective way to waterproof the plywood of your boat. Elastomeric sealants are designed to expand and contract with changes in temperature and humidity, making them ideal for boat environments.

They are versatile and can be used on any surface, including rubber, plastic, aluminum, and fiberglass. Apply the sealant to the edges of the ply by using a caulking gun. Ensure that you fill any gap or cracks between the plywood and adjacent surfaces.

6. Use Varnish

Varnish is another popular method of waterproofing plywood boats. Before applying the varnish, it’s important to sand the surface and apply a layer of primer for better adhesion. Once the primer has dried, apply multiple thin layers of varnish to the wood, letting each layer dry before applying the next. Varnish can help protect your plywood boat from sun and water damage.

7. Use Liquid Rubber Sealant

A liquid rubber sealant is an excellent way to waterproof plywood boats since it creates a strong barrier against moisture. When using a liquid rubber sealant, make sure to clean the wood surface first before applying it. Also, use a brush to apply the sealant on the plywood edges and any joints or gaps. Let it dry before using your boat in the water.

That’s it! You’ve now learned seven different methods for waterproofing plywood for a boat. Taking the time to waterproof your boat’s plywood properly will help protect it from water damage, extend its life, and make it look better overall. So, don’t forget to add this important task to your next boatbuilding or restoration project! Happy sailing!

5 Considerations Things When You Need to Waterproof Plywood for a Boat

1. choose the right type of plywood.

When waterproofing plywood for a boat, choosing the right type of plywood is important. Marine-grade plywood is designed to withstand exposure to water and humidity, making it an ideal choice for boatbuilding projects. Ensuring the plywood has been treated with a waterproof sealant or paint is also important.

2. Use Epoxy Resin

Epoxy resin is one of the best materials for waterproofing plywood for a boat. This material forms a strong bond between the wood fibers and creates an impenetrable barrier against moisture and humidity. It can also be used with fiberglass cloth for added strength and durability.

3. Apply a Waterproof Sealant

Applying a waterproof sealant is another effective way to protect plywood from water damage. Several types of sealants are available, including acrylics, polyurethanes, and silicone-based formulas. For maximum protection, applying multiple coats of sealant over the entire wood surface is best.

4. Paint the Plywood

Painting the plywood with marine-grade paint will also help to protect it from water damage. It is important to use a paint that is specifically designed for use on boats, as regular paints may not be able to withstand exposure to saltwater or other harsh elements found in marine environments. Additionally, make sure that you apply several coats of paint for maximum protection against moisture and humidity.

5. Monitor Conditions Regularly

It is also important to monitor conditions regularly to ensure that your waterproofing efforts are successful. Ensure there are no signs of water damage or deterioration, such as warping or cracking in the wood, as these could indicate that more protective measures need to be taken to keep your boat safe from water damage.

5 Benefits of Waterproof Plywood for Boat

1. durability.

Waterproof plywood is an incredibly durable material that is perfect for boat building. It is made from layers of thin sheets of wood glued together with waterproof adhesive. This creates a strong, stable material that can withstand the rigors of life on the water. The layers also help to reduce warping and cracking, which can occur in traditional wood when exposed to moisture or temperature changes.

2. Lightweight

Waterproof plywood is also much lighter than other types of wood, making it easier to work with and transport. This makes it ideal for boat building, as it reduces the overall weight of the vessel and makes it easier to maneuver in the water. Additionally, its light weight means that you don’t need as many supports or reinforcements, which can save time and money during construction.

3. Cost-Effective

Another benefit of waterproof plywood is that it is much more cost-effective than other materials used for boat building, such as fiberglass or aluminum. Not only does it cost less upfront, but it also requires less maintenance over time, saving you money in the long run.

4. Versatile

Waterproof plywood is also very versatile and can be used for various applications on boats such as decks, bulkheads, floors, and transoms. It can be cut into any shape or size needed, making it easy to customize a boat according to your needs. Additionally, its strength allows you to use fewer pieces when constructing a boat, saving both time and money.

5. Eco-Friendly

Finally, waterproof plywood is a great choice if you’re looking for an eco-friendly option for your boat-building project. Plywood comes from renewable sources such as trees harvested responsibly without damaging forests or ecosystems around them.

Additionally, because it doesn’t require harsh chemicals or treatments like fiberglass, its production process has minimal impact on the environment compared to other materials used in boat building.

With all of these benefits, waterproof plywood is an ideal choice for boat-building projects and can help you build a strong, durable vessel that will last for years to come. Make sure to do your research before selecting a type of plywood so that you get the best results for your project.

5 Common Mistakes People Make When Trying to Waterproof Plywood for a Boat

1. not applying enough sealant.

One of the most common mistakes people make when trying to waterproof plywood for a boat is not applying enough sealant. Plywood is highly porous and must be thoroughly sealed to keep it watertight. Applying a generous amount of sealant is important, ensuring that all surfaces are completely covered. If the sealant isn’t applied properly, water can seep into the wood, leading to rot and decay.

2. Not Using Marine Grade Plywood

Another mistake people make when trying to waterproof plywood for a boat is not using marine-grade plywood. Marine-grade plywood is designed specifically for use in boats and is much more resistant to water damage than regular plywood. Regular plywood may look similar, but it doesn’t have the same level of durability and won’t hold up as well over time.

3. Not Preparing the Surface Properly

It’s also important to prepare the surface of the plywood before applying any sealant or paint. The surface should be sanded until smooth and free from any dirt or debris that could prevent the sealant from adhering properly. Any existing paint should also be removed, as it can prevent the new coat from bonding correctly with the wood.

4. Not Using Multiple Coats of Sealant

Applying only one coat of sealant will not provide enough protection against moisture and will need to be reapplied more often than if multiple coats were used initially. Multiple coats will create a stronger barrier between the wood and moisture, providing better protection over time and making it easier to maintain in future years.

5. Not Letting Each Coat Dry Completely

Finally, it’s important not to rush through this process by skipping steps such as waiting for each coat of sealant or paint to dry completely before applying another layer. This step is essential for all layers to bond properly and form an effective waterproof barrier between your boat and any moisture that may come into contact with its surface over time.

Waterproofing plywood is a vital step in building a long-lasting and durable boat. Choosing one of these waterproofing methods will help extend the life of your boat and reduce maintenance costs in the long run. However, each method has advantages and disadvantages, so choosing a method that best suits your needs and budget is important. 

Whatever method you choose, follow the correct application instructions to achieve the best results. Proper waterproofing allows you to enjoy your boat for many years. Thanks for reading our post about how to waterproof plywood for boat.

Adrian Green

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How To Waterproof & Seal Plywood for Outdoor Use (Step by Step)

By: Matt Hagens

Disclaimer: Obsessed Woodworking is reader-supported . I may receive a small commission if you purchase anything through my site.

Waterproofing plywood is essential for outdoor projects since moisture exposure causes swelling, warping, and rotting that compromises the wood’s structure and longevity.

This article provides instructions on how to do it effectively to protect outdoor structures for years.

Choosing the Right Products for Waterproofing

Selecting the right waterproofing product is essential for effective protection of plywood in outdoor settings.

• Paint : Offers basic moisture protection and is ideal for projects where appearance is important.
• Polyurethane : Known for its durability and clear finish, preserving the wood’s natural look.
• Epoxy : Provides a strong, durable finish, perfect for heavy water exposure areas like boat decks.
• Rubber-like Sealants : Extremely water-resistant and flexible, ideal for sealing irregular surfaces.

Epoxy is my top choice, but it’s expensive and harder to work with. If you decide to use epoxy, I highly recommend Total Boat products .

Step-by-Step Guide to Waterproofing Plywood

Properly waterproofing plywood is key to ensuring its longevity and durability, especially in outdoor settings.

1) Selection of Plywood and Waterproofing Products

• Choose the right type of plywood for your project, considering factors like water exposure, desired finish, and durability.
• Avoid the mistake of using the wrong type of plywood or waterproofing product for your specific environment.

2) Preparation of Plywood

• Cleaning : Ensure the plywood is clean and dry. Remove any dirt, grease, or debris.
• Sanding : Sand the surface with medium-grit sandpaper for better adhesion.
• Filling Gaps : Use an exterior-grade wood filler for gaps or cracks to prevent water seepage.

3) Apply The Waterproofing Sealant

• Following the manufacturer’s instructions, apply the chosen waterproofing product (paint, polyurethane, epoxy, or rubber-like sealants).
• Avoid applying a too thick coat, which can lead to uneven coverage and longer drying times. Instead, apply multiple thin coats.
• Pay special attention to edges and corners, as these areas are more prone to water penetration.
• Work in a well-ventilated area and allow sufficient drying time between coats, as rushing this process can result in a tacky finish and reduced effectiveness.

Maintenance and Care

Maintaining waterproofed plywood is essential for its longevity.

• Regular Inspection : Periodically check for signs of wear, such as peeling, cracking, or discoloration of the waterproof layer, and for any soft spots or swelling in the wood.
• Clean Regularly : Keep the surface free from dirt and organic growth. Use mild detergent and water, avoiding harsh chemicals.
• Prompt Repairs : Address any damage or wear immediately to prevent further deterioration.
• Reapplication of Waterproofing Products : Look for signs like water absorption or loss of water beading on the surface to indicate that it’s time to reapply the product.
• Avoid Standing Water and Sun Damage : Design structures to prevent water pooling and consider UV-resistant sealants for sun-exposed areas.

Proper techniques to seal and maintain plywood ensure durable, long-lasting outdoor structures.

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Do You Need to Seal Marine Plywood?

Much as the Marine-Grade Plywood is strong, long-lasting, and resistant to moisture, it still requires that you add an extra seal on it to prevent moisture from damaging it.

Sealing your marine plywood is critical for its durability. Failure to protect it could lead to rotting as well as discoloration. As soon as you seal it, you can go further and add other finishes such as polyurethane .

Table of Contents

What Is Marine-Grade Plywood?

According to APA, Marine-grade plywood is a special panel created using Douglas fir or Western Larch.

Marine-grade plywood, simply marine plywood , confuses a lot of people to think that it is waterproof. It is a good-quality, hardwood plywood that has waterproof glue; this wood is not treated using chemicals hence does not resist rot.

This wood exists in 4 grades, with the better grades being lightweight, strong, and comes with no forms of defects. It is these exceptional qualities that make marine plywood a popular choice when constructing boats and their parts. Additionally, this wood makes a perfect choice for those looking to make doors along the coastlines, but first, you need to give it a protective finish.

How to Seal Marine Plywood

Until this point, you at least know that Marine-Grade Plywood is strong, lasting, and above all, comes with some level of resistance against moisture; even so, it would be best if you seal it for extra protection. Here’s the process of sealing marine plywood:

Requirements

• Sanding block
• Paper towels
• Foam roller
• Sandpaper 
• Paint basin

Step One: Clean Surface Of Plywood

Dip a piece of cloth or rag into acetone and use it to clean the surface of your plywood board. Acetone, in this case, helps in getting rid of grease and other unwanted stains from your wood. After cleaning with acetone, allow it time to dry. It should take about an hour or two for the acetone to dry.

Fine-grit sandpaper is the best for sanding plywood. You can fix it on your wood sander and use it for several minutes to achieve the best results. Use a piece of cloth or a shop vac to eliminate sawdust particles from your wood. 

Step Three: Apply Sealant Using the Foam Roller

Have your selected sealer ready in a basin for the step. Here, it would be best if you dipped the foam roller into the wood sealer. If you want to avoid “picking” too much sealer, then roll the brush against the sides of the basin. I recommend that you roll the sealer you choose for this purpose onto a 2-by-2-foot area to ensure that the sealer does not dry too quickly. 

Even as you apply the formula, ensure that you are focusing on one section at a time until you cover the whole plywood with a thin coat. One way of eliminating brush marks from your sealer is by dragging a foam tipping brush over the sealer when it’s still wet. Make sure that you are painting horizontally and not vertically.

Step Four: Allow the Formula to Dry

After you have applied your formula, you must allow it to dry. Usually, it takes between one and two hours for the coat to dry. Once the surface dries, you can add more thin layers as you see fit for your project. At this stage, feel free to alternate between vertical and horizontal strokes. 

About four thin coats of the sealer should do the job and give you the best finish for your sealing project.

How Long Does Marine Grade Plywood Last?

Suppose you compare the Marine Grade Plywood and its traditional counterpart. In that case, you will find it far more durable, especially if you use the two in areas prone to water and moisture like exterior projects such as picnic tables . So, how long does marine grade plywood last?

The Marine grade plywood lasts between 10-25 years, depending on the quality and how you use the plywood. 

It would help if you had a proper understanding of some of the factors that influence the plywood’s durability so that you know exactly what to do to help prolong its service life.

Factors that Affects the Lifespan of Marine Grade Plywood

There’s a notable difference in the durability of marine-grade plywood, and the difference is dependent on many factors such as the quality of the plywood, the amount of moisture the plywood is exposed with overtime. Other factors include the chemicals used in the treatment of plywood. If you are looking to project the number of years your plywood can serve you, it would be best to account for all these factors.

If you are in the market for marine plywood, you need to understand various plywood grades and settle for the one that will make a perfect fit for your project in question- influenced by the use and area in which the project is based. With the right plywood, you can rest assured of the best Return on Investment (ROI) from your projects.

Here are some of the factor:

• Quality Of Your Plywood

Plywood exists in up to four grades ranging from A-D. Grade A is the best quality of all four, while D is the lowest quality.

As you’d expect, the plywood with the highest quality stands for every chance of lasting longer than the rest. The wood is either A-grade or B-grade in marine-grade, with grade A lasting longer and better than grade-B.

As you choose your plywood for projects best known to you, you must get the right supplier. Marine-grade plywood undergoes a more extensive treatment process, which is why certified and best-reviewed lumber suppliers are the most reliable for producing waterproof plywood that is durable. 

Additionally, I encourage that you only make purchases of plywood from the suppliers you trust and have a reputation for providing high-quality and lasting wood

• Moisture Levels in the Environment

Even though plywood has high moisture resistance, it is not permanently resistant as it gets affected by water in the long run. Plywood that sees more exposure to water will break down faster than the one used in areas that experience low levels of moisture.

Bottom line, a Marine grade plywood in water exposure areas, such as in dock construction, can last at least fifteen to twenty years. When the same plywood is used in home decks or interior flooring, it can last up to twenty-five years or more, especially if you accord it proper care.

NOTE: You can use a moisture meter to determine the moisture level in any wood including plywood.

• Chemicals Used In the Treatment 

Marine-grade plywood is special because it is treated with chemicals. The chemicals play an important role in repelling water and, in turn, prevent moisture from getting into the wood cells to cause damage. It would be best if you offered the plywood further protection against moisture using wood sealers , especially those made specifically for marine plywood .

Buy READY SEAL Here :

Different Grades of Plywood

A-grade plywood : It is the best quality plywood, making it the most expensive in the class. Its veneers are flawless, making it smooth and arguably the easiest to paint or other finishes.

B-grade plywood : The B-grade plywood is a bit less smooth than its A-grade counterpart; however, it has a solid foundation. This grade of plywood has some minor flaws, but you can repair them to achieve top quality.

C-grade plywood : As for this grade, you get a few knots in the sheets; usually, the knots have a diameter of up to 1.5 inches.

D-grade plywood : It is by far the cheapest type of plywood veneer. The sheets have not undergone repairs and have slightly larger flaws, with knots as large as up to 2.5 inches in diameter.

There are no words to describe how good marine plywoods are for projects in areas that see a lot of moisture, especially the maritime environments. With the right grade of plywood, your projects stand a chance against the test of time, delivering top performance in the process. Much as marine plywood is durable and can withstand moist conditions, it still has some shortcomings, especially due to prolonged exposure to water. Even as you use it for different purposes…

Yes, you need to seal your marine plywood. Much as it can resist moist conditions, it gets overwhelmed with time and will start breaking down. Select the right sealers and enhance the durability of your marine plywood.

The natural durability of marine plywood coupled with enhanced protection against elements such as water and UV rays will ensure that your structure can last up to 2 decades or more, is a coastline environment.

I hope you have read this post and gotten insightful information on whether or not you should seal your marine plywood. If you have questions, additions, or any form of suggestion that will make this content better, kindly share it with me in the comment section below.

Tyron Otieno

Tyron is an avid woodworker and writer. He founded this website to help other woodworkers, whether hobbyists or professionals by sharing his knowledge and experiencie after a decade of woodworking.

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IDEAL FOUNDATION FOR VARNISH

EASY TO USE, EASY TO MAINTAIN

WORKS ON ALL TYPES OF BARE WOOD

DRIES FAST, NO SANDING BETWEEN COATS

Wood Sealer Varnish Primer

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Wood Sealer fills the grain, seals the wood, and levels the surface for consistent, beautiful finishes

The goal of restoring a wooden boat, building a piece of wood furniture, or creating a wooden work of art is to make the wood itself look great, and make sure it stays that way for as long as possible – regardless of the type of wood, and whether it’s indoors or out. Especially if it’s outdoors, and the varnish finish will be exposed to sun, salt, and harsh weather. Make 1-part varnish finishes look better and last longer by coating new or bare wood with TotalBoat Wood Sealer first. It seals the wood fibers and fills the grain to smooth out the surface, removing highs and lows so varnish can be applied to a uniformly level surface, without thinning first. TotalBoat Wood Sealer has a light amber color that enhances the natural beauty of bare wood. If the wood is stained, marine wood stains typically only fill the wood grain and change the color, but don’t seal the wood. So you still need to apply a sealer before finishing. TotalBoat Wood Sealer can seal in the color of stained wood without muddling, just be sure the stained surface is completely dry before applying the sealer, and do a small test first to ensure compatibility.

Seals all types of wood effectively

Plywood is used in so many projects, from building decks to building docks. It’s very porous and is infamous for checking – those long, thin cracks running lengthwise in the wood grain. They’re caused because wood starts drying on the outside first. This creates tension, which can spawn lengthwise splits on the surface of a board, either on the flat face, the end, or internally. Plywood must be sealed before being varnished or painted to prevent checking and delamination of any finish coating. Sealing also primes the wood surface, which has two benefits. First, it prevents the finish coats of varnish or paint from sinking into the wood, which prevents you from paying more because you’d have to use more product. Second, this thin varnish primer also bonds to the wood and creates a level foundation for finish coats of varnish to bond to, so they don’t lift in large sections later. Keep in mind that because plywood is so porous, it may require 3 coats of TotalBoat Wood Sealer. In addition, oily hardwoods like teak and mahogany also need to be sealed to prevent their natural oils from lifting varnish or paint coatings. After properly preparing new or bare wood to remove any oil, grease, dust, or dirt, apply 2 coats of TotalBoat Wood Sealer to seal and level oily woods.

Easier than using thinned varnish for sealer coats

The viscosity of varnish is such that it doesn’t penetrate wood grain easily. For that reason, varnish is usually thinned for the first couple of coats, and needs to be sanded between coats. On the other hand, TotalBoat Wood Sealer’s viscosity penetrates and seals wood more readily than thinned varnish, and does not require sanding between coats. It also dries faster than thinned varnish, so you won’t need to wait as long to start building finish coats. What’s more, the final coat of TotalBoat Wood Sealer is actually easier and faster to sand than thinned varnish, and because it dries more quickly, you’ll be ready to apply your finish coats of varnish sooner – which can save you a full project day.

Wood Sealer works and dries faster than other clear marine wood sealers — and it’s UV-stable, too

TotalBoat Wood Sealer is definitely not a pain in the arm like other clear marine wood sealers, because you don’t have to sand between coats. It has a viscosity that flows more easily into wood grain, and it dries faster, too, so recoating can happen in less than half the time. It also contains UV blockers that protect all the way down to the wood, which other marine sealers don’t do. Better still, with its longer open time, it won’t skin over and glob up in the can like other clear marine wood sealers do.

Makes for a great finish, but it’s not a finish coating

Use it with either of the TotalBoat 1-part varnishes Lust Marine Spar Varnish or Gleam 2.0 Spar Varnish , which don’t require sanding between coats, either. Together, TotalBoat Marine Wood Sealer and any TotalBoat 1-part varnish gives you a clear, level, beautiful finish in less time — every time.

Wood Sealer Varnish Primer Details

• One-part, clear amber gloss wood sealer fills wood grain and seals the fibers against moisture and sun damage.
• Creates a level surface ideal for 1-part varnish finishes like TotalBoat Lust and TotalBoat Gleam 2.0.
• UV stable and does not need sanding between coats.
• Dries fast so you can recoat in just 2 hours @ temperatures above 72°F.
• Allows 1-part varnishes to be used without thinning first, so more varnish is available for the finish coats.
• Works on all types of new or bare wood, including plywood and oily woods like teak and mahogany.
• For interior and exterior use above the waterline.
• Color: Clear Amber
• Sizes: Quart, Gallon

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Special Brushing Thinner 100

Spray Thinner 101

TECHNICAL DATA

• Substrates: Wood, previously varnished wood in good condition, or properly prepared epoxy surfaces
• Application Method: Brush, Roll, or Spray
• Application Temperature/RH: 45-105°F or 50-90°F, relative humidity 0-85% or 0-90%
• Application Film Thickness: 1-1.5 mils dry @ 3 mils wet
• Number of Coats: 2-3 (depending on the porosity of the wood)
• Minimum Overcoat Time: 1 hour @ 80°F, 3 hours @ 65°F, 8 hours @ 50°F
• Maximum Overcoat Time Without Sanding: 48 hours
• Important: TotalBoat Wood Sealer is intended as an initial coating to seal wood and prevent absorption of finish coats of varnish. For added depth, gloss, durability, and UV protection, overcoat Wood Sealer with 1-part varnish. Do not use TotalBoat Wood Sealer under two-part epoxy or two-part varnish or polyurethane paint systems.
• Finish: Gloss
• VOC Content: Less than 530 g/L
• UV Stable: Yes
• Food Safe/Food Contact Safe (Once Cured): No
• Coverage: 60-100 square feet per quart @ 3 mils wet
• Thinner: Brushing/Rolling - TotalBoat Special Brushing Thinner 100; Spraying - TotalBoat Spray Thinner 101
• Surface Prep Solvent: TotalBoat Dewaxer & Surface Prep or TotalBoat Special Brushing Thinner 100 or TotalBoat Spray Thinner 101
• Cleanup Solvent: TotalBoat Dewaxer & Surface Prep or TotalBoat Special Brushing Thinner 100 or TotalBoat Spray Thinner 101

• Application methods:
• Application temperature/RH:
• Number of coats:
• UV resistant?
• Units of measure:
• Best for: Pre-varnish treatment for 1-part varnish. Seals wood so varnish is available for the finish coats - no sanding needed between coats.
• Color: Clear amber
• Application methods: Brush, Roll, or Spray
• Application temperature/RH: 45-105°F; 0-85% RH
• Number of coats: 2-3 (typically)
• Thinner: TotalBoat Special Brushing Thinner 100, for brushing and rolling applications; TotalBoat Spray Thinner 101, for spraying and cool weather brushing/rolling applications
• Cleanup: TotalBoat Dewaxer & Surface Prep or TotalBoat Special Brushing Thinner 100 or TotalBoat Spray Thinner 101
• Coverage: 60-100 sq ft/qt @ 3 mils wet
• UV resistant? Yes, but needs to be coated with varnish.
• Units of measure: Quart, Gallon
• Brightwork on boats, strip canoes, kayaks
• Gloss, Satin
• Clear amber
• Brush, Roll, or Spray
• 45-105°F; 0-85% RH
• 4-6 (minimum)
• TotalBoat Special Brushing Thinner 100 for brushing and rolling applications; TotalBoat Spray Thinner 101 for spraying and cool weather brushing/rolling applications
• TotalBoat Dewaxer & Surface Prep or TotalBoat Special Brushing Thinner 100 or TotalBoat Spray Thinner 101
• 360-400 sq ft/gal @ 3 mils wet
• Pint, Quart Kit, 2 Quart Kit, Gallon Kit
• Rapid recoating, without sanding between coats. Great for brightwork, wooden canoes and kayaks.
• High Gloss, Matte
• 6-8 coats (minimum)
• High Gloss or Satin - Pint, Quart, Gallon, 2 Quart Kit; High Gloss and Satin - 2 Quart Combo Kit
• A natural-looking finish on brightwork, wooden canoes, kayaks, signage, artwork. Easy cleanup with soap and water.
• Gloss, Satin (Low Sheen)
• • Halcyon Amber Gloss - Clear gold/amber • Halcyon Clear Gloss - Clear, with very slight amber undertones • Halcyon Clear Satin - Clear, with very slight amber undertones
• Brush, Roll & Tip, or Spray
• 50-90°F; 0-90% RH
• 2-3 (minimum)
• Water (up to 20%, but is usually not needed)
• Mild soap and water
• 80-100 sq ft/qt @ 3 mils wet
• Pint, Quart, 4 Quarts. NOTE: Satin finish is not available in a 4 Quart size.

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Marine Wood Finish

• TotalBoat Wood Sealer Varnish Primer Technical Data

FREQUENTLY ASKED QUESTIONS

What kinds of wood can this be used on?

Can the marine wood sealer be used over oil-based stains, why should stained wood be sealed before varnishing, does this varnish primer dry clear, or is it a stain, does wood sealer provide uv protection, can marine wood sealer varnish primer be used as a finish, can totalboat wood sealer be used below the waterline, should it be thinned for easier application, how many coats do i need to apply, how long do i need to wait before recoating, how long does varnish primer take to dry.

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Waterproofing Plywood: 3 Ways to Protect Plywood

Plywood is an excellent material that is used in different types of construction. From building homes to creating decks to crafting particular items, plywood is relatively inexpensive, durable, and comes in different types that are flexible for your needs.

One disadvantage is that most plywood is not waterproof. While there are certain types that are water-resistant such as marine plywood, all plywood will need some type of waterproofing if you want to protect it from the humidity.

The benefits associated with sealing plywood include the following.

• Protects from Humidity and Ultraviolet (UV) Rays
• Inhibits the Rotting Process
• Reduces Splitting

Best Methods of Waterproofing

There are several different methods of waterproofing that can be used to protect plywood. You should choose the one that best suits your needs. Keep in mind that you can do the work yourself or hire a professional. Depending on the size of the job, you may want to get professional assistance to ensure that it is done right.

Otherwise, if the area to be covered is relatively small, then you can do the work yourself by using one of the following methods.

• Epoxy Sealing

This is a popular type of sealant that can be easily used on most plywood. The advantage of an epoxy sealing product is that it protects the wood while allowing it to retain its natural color. Plus, the epoxy itself is quite strong and can be used on plywood that is both indoors and outdoors.

To prepare the plywood, you will need to sand the surface to remove any dirt, debris, and loose particles. Then, apply the epoxy sealant as per the instructions. This usually means applying the epoxy in an even layer while it is still in a liquid state. Once the components of the epoxy meet, they tend to dry and harden quickly to create a protective layer on the surface of the plywood.

One substantial advantage of epoxy is that the forms a hard, durable layer that is stronger than paint or hard oil. This means that it can resist the elements for a long time. Plus, it can be reapplied without having to remove the older layer of epoxy, unlike paint. If there is a downside, it is the limited variety of epoxy in terms of coloring or tinting the plywood.

• Penetrating Hard Oil

This is an oil that as the name implies penetrates the surface of the wood which seals it against intrusion by moisture. The oil itself can be applied across the surface of the wood evenly and allowed to soak in to seal it up.

You should use a penetrating oil that is designed for the wood itself. This means one that is meant to be used for waterproofing and keeps the wood moist enough so that it retains its flexibility and strength. You can start by sanding the surface to remove any loose particles, dirt, or debris. Once sanded, apply the oil in an even layer.

Depending on the type of penetrating oil used, you may need to add another coat once the surface has dried. The oil is best used on plywood that is not exposed to the elements. While it does offer some protection, the constant wind, sunlight, and exposure to moisture will dry out the oil that is near the surface over time.

This means that you should use penetrating oil on plywood that is not going to be outdoors unless you want to reapply it frequently. Although it may be easier and less time-consuming than paint or a spray epoxy, the oil itself will need to be reintroduced far more frequently unless the plywood itself remains out of the elements.

• Paint or Spray-On Latex

Painting is one of the most common methods of sealing plywood and one of the most cost-effective. Polyurethane or latex bases paints provides a layer of protection that seals the porous surface. But just as importantly it can decorate the plywood if the exterior is going to be seen. You can paint a deck, wall, or other objects that are crafted from plywood.

You must prepare the surface by sanding it smooth. This helps the paint to attach to the wood and create a smooth surface which is quite desirable both in visual terms and texture. Plus, sanding will remove any loose particles of wood that might detach after it has been painted. Once the sanding process is complete, you can apply the first layer of paint, use a primer, or apply spray-on latex.

Spray-on latex is essentially the same as paint as it provides a layer that sticks to the surface which seals up the porous plywood. If the plywood itself is not going to be seen or directly exposed to the elements, then a couple of coats of spray-on latex may be enough. Otherwise, you can use the product as the first coat, let it dry, then add a layer of paint over the top.

Once you have completed painting the plywood, you will need to add a new coat from time to time depending on the wear it receives. When the time comes to repaint the plywood, you will need to strip the old paint away first, sand the surface again, then add at least two coats of new paint or spray-on latex to do the job.

Painting or spray-on latex is generally best for surfaces that will be directly exposed to the elements. This means that the plywood is on the outside of the home such as a deck. However, painting can be used in most situations involving plywood as it is relatively inexpensive, versatile, effective, and long-lasting.

Waterproofing plywood is relatively straightforward. You simply need to choose the method that works best for your needs. Keep in mind that the waterproofing process does take time and effort. Plus, it will need to be repeated from time to time for maximum benefit.

Dan Miller is a professional toolmaker with extensive experience in the metalworking and tooling industry.

An avid DIY enthusiast and passionate hobbyist woodworker, Dan shares his expert knowledge here.

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• 9 Types of Plywood & Their Uses
• BCX Plywood and Its Uses
• Is Birch Plywood Waterproof?
• Using Router on Plywood Without Tearout

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Using spar varnish

• Thread starter Rsb1970
• Start date Feb 10, 2017
• Feb 10, 2017

I'm going to seal some plywood for my boat floor. Can I use spar varnish? Will that be enough to seal it? Then I'm going to put Capet down.  

Woodonglass

Supreme mariner.

• Feb 11, 2017

What kind of plywood? If it's only ext.grade then I'd say it might be IF you applied 4-5 coats and paid extremely close attention to the edges. The best coating would be 2 coats of Epoxy or Polyester Resin and CSM.  

Starmada Splash of the Year 2014

If your replacing the deck in an aluminum Crestliner then the spar varnish would work fine, lot's of us use it.  

Watermann said: If your replacing the deck in an aluminum Crestliner then the spar varnish would work fine, lot's of us use it. Click to expand...

I would be interested in hearing how "spar varnish" became so popular here as a 'wood sealent'. When I want to apply a protective 'sealent' to wood in a non-visual area my choice would pretty much always be paint. The higher solids content will build faster and provide more abrasion resistance. As for which one 'soaks in more', try stripping both paint and varnish off a surface and find out which one sticks in the grain more. Just because it is clear, like epoxy, doesn't mean it is more like epoxy than paint. (I definately agree epoxy is #1, but comes with a price tag.) I have never understood the recommendation. .. Just wondering.  

Epoxy is by far the best, the other products used aren't even close. Paints, spar varnish and other blends are short term at best, they don't start out that water resistant and get worse quickly, so they need to be reapplied frequently to be of much value.  

Watermann said: Ned you could always google the spar we're using. Here is what I use http://www.minwax.com/wood-products/...-spar-urethane Hope that helps you 'understand' why spar is a 'sealant'. I agree paint is a great choice for sealing just about any material and I usually do both spar and paint on things like transom wood. Spar can even be exposed to the light of day and not fail like epoxy resin which has to be covered with something so UV doesn't ruin Click to expand...

ondarvr said: Epoxy is by far the best, the other products used aren't even close. Paints, spar varnish and other blends are short term at best, they don't start out that water resistant and get worse quickly, so they need to be reapplied frequently to be of much value. Click to expand...

Watermann said: The OP wanted some advice on using Spar from members that have used it before, everyone is entitled to their own opinions but it should be weighed against those who haven't any experience or any builds in their sig line. As far as penetration into the plywood goes, nothing gets past the first layer of glue. I've cut holes in ply treated with spar and it's penetrated down to the first glue layer. Click to expand...

Ned L said: I would be interested in hearing how "spar varnish" became so popular here as a 'wood sealent'. When I want to apply a protective 'sealent' to wood in a non-visual area my choice would pretty much always be paint. The higher solids content will build faster and provide more abrasion resistance. As for which one 'soaks in more', try stripping both paint and varnish off a surface and find out which one sticks in the grain more. Just because it is clear, like epoxy, doesn't mean it is more like epoxy than paint. (I definately agree epoxy is #1, but comes with a price tag.) I have never understood the recommendation. .. Just wondering. Click to expand...

If I just use the minwax helmsman spar urethane how long would it last? A couple months, a couple years?  

Tnstratofam

I used the helmsman spar urethane varnish on the transom of our SS160 when we replaced it 3 years ago. The boat stays covered in our driveway or parked in the dry in our garage when we aren't using it. I coated both sides with 3 coates and saturated the edges with 6 coats. It looks as good now as it did the day It was finished. I also used the spar varnish on the casting deck I built for the bow. I covered it with carpet and it too has held up well. I agree that epoxy is the best protectant but spar varnish has worked well for me. Mind you our SS is an alluminium bow rider and I can inspect the transom easily.  

Rsb1970 said: If I just use the minwax helmsman spar urethane how long would it last? A couple months, a couple years? Click to expand...

• Feb 12, 2017

Rsb1970 said: So you're saying to just use paint? What kind? Click to expand...

Watermann said: I knew this would happen, confusing comments from people who have never used either product. How old is your boat? I'm assuming it's an aluminum Crestliner made in 1987. So the untreated factory deck is needing replaced after 30 years of use and I'm sure some abuse. Just to add perspective there was no magical epoxy resin or worthless spar on the decking to seal it from the factory in 1987 and it lasted for decades. So anything you do to seal the wood will be better than it was new and last a very long time if you cover it up and not allow the elements to ravage the interior. On a side note have you checked the transom wood for any signs of decay? Click to expand...

I have a couple of Starcrafts from the 60's, they have the original transom wood, one had a plywood floor placed in it at some time in the late 60's, because the wood was of a decent grade and left open, it lasted for 3 -4 decades with zero attention. Now if you cover it with carpet, vinyl, or something else like a mound of wet leaves while sitting in the side yard, the lifespan is shortened dramatically. Products like spar varnish, paint, Thompson's Water Seal, etc, are not going to extend the lifespan much once carpet is laid over it, epoxy is the only product that will extend the life of the wood, and only if you don't drill holes in it and leave them unsealed. ​My boats were stored outside on the beach, but upside down most of the time, so the plywood was dry except when it was being used. Plywood is cheap and easy to replace, so I don't do much of anything to protect it on an aluminum boat, at most I'll use some porch paint and grit to make a non skid surface if needed. ​These boats were used like tools, checking crab pots, fishing, shrimping, shuttling to larger boats that were kept tied to buoys all summer, etc, we did nothing to make them look better, this allowed the wood to survive longer.  

To add, yes I've used spar varnish, the results vary greatly on the type of ply you're coating and where it will live. Fir plywood is desired for it's rot resistance, but the surface checks badly after a year or so if it's exposed to the elements, spar varnish isn't strong enough to stop the checking (cracking and widening of natural gaps in the plywood surface), frequently the checking starts in a year or so and defeats the purpose of using any type of coating to protect the wood at all. Epoxy is strong enough to resist the checking, so it survives much longer as a protective coating.  

ondarvr said: ​Are you going to put something like carpet over it, and will it be stored indoors or out? Click to expand...

How To Waterproof Plywood For A Boat (2 Methods)

Waterproofing plywood for a boat is easy but will take some patience to ensure a smooth waterproof finish. This article provides two plywood waterproofing methods, the steps needed for each, and some helpful information. Let us get ready for the launch.

Table of Contents

Method 1. Waterproofing Plywood For A Boat With Epoxy Resin

The first method to waterproof plywood for a boat is by using Epoxy resin. The resin is long-lasting and highly durable and is the preferred waterproofing method by boat builders.

Step 1. Setup And Materials

Setting up a proper work environment will be essential when waterproofing plywood. Some of the materials dry very quickly, and if the correct tool is not within reach, it could result in extra work that will need to be done to correct it. Here is a list of some of the materials you will need:

• Clean cloth
• Disposable mixing container for the epoxy
• Epoxy kit (resin and hardener)
• Hairdryer or heat gun
• Paint stick
• Paper towels
• Sanding paper (80,120 & 200 grit)

Place the materials within reach and lay the tarp on the floor to prevent any epoxy and sawdust from adhering to the floor. When using epoxy, it is recommended to use latex gloves when mixing and applying it to the wood.

Step 2. Cleaning The Plywood

The plywood should be clear of any oil, mold, or wax. Wipe the wood off with acetone and a cloth or paper towel. The acetone is great for cleaning the contaminant on the wood, and it assists in evaporating any moisture.

Cleaning the wood before the sanding process will prevent any grime from smearing into the wood. Make sure to have sufficient airflow when working with acetone.

Step 3. Let The Plywood Dry

After wiping the plywood down with acetone and ridding it from all contaminants, let it dry. This process can be hurried up by using a hairdryer or heat gun. Be careful not to place the heat source too close to the plywood, as it can darken the wood slightly.

Step 4. Sanding The Plywood

Now that the plywood is clean and dry, it’s time to remove the top layer of wood by sanding it. Start with the 80 grit sandpaper. Sand the wood in a circular motion, as this motion will leave a more even finish on the wood.

It is vital that you sand the edges and corners of the wood, as any un-sanded areas might not absorb the epoxy sufficiently. If there are any deep imperfections, use a quality wood filler to cover them and sand down the excess.

Step 5. Mixing The Epoxy

Mix the two epoxy solutions together (resin & hardener) in a disposable container in a well-ventilated area. Follow the mixing instructions for the epoxy kits as the mixing ratios can vary between manufacturers. 

Use a paint stick to scrape and stir the mixture for five minutes so that it is well mixed and starts thickening to a syrupy consistency. If air bubbles form in the mixture, do not worry as they can be removed later.  

Step 6. Laying The Epoxy

The epoxy will start thickening up quickly, so time is of the essence. Dispense the epoxy onto the middle of the plywood. Spread the epoxy evenly over the wood surface with a foam brush. It is crucial to cover the whole piece of wood, including the edges. Once the wood is evenly coated with epoxy, wipe off the excess with the foam brush.

Step 7. Removing The Air Bubbles From The Epoxy

If any bubbles have formed on the epoxy, they can be removed with heat. Using a hairdryer or heat gun, move the heat back and forth over the air bubbles until you see them pop. The epoxy will now need to cure and harden for four hours.

Step 8. The Second Coat Of Epoxy

After four hours, the epoxy will not be completely hard and dry, and it will have a tacky texture to it. The sticky texture means that it is ready for the second coating of epoxy. Follow the same process as Steps 5 and 6 to cover the wood. Make sure to cover the wood evenly and do not forget the corners and sides.

Once the plywood is evenly covered, leave the epoxy to cure and harden for 24-36 hours. Ensure that the plywood is not placed in direct sunlight while it is hardening, as the UV rays will cause a chalking effect.

Step 9. Removing The Wax Layer From The Epoxy

When the epoxy has hardened, you will notice a waxy layer covering it. To remove this, use acetone and a cloth and wipe down the plywood. This will also remove any other contaminants that might be on the wood.

Step 10. The Second Sanding

Sanding the epoxy is a necessary step in waterproofing plywood. The sanding will remove any air bubbles that might be left. Start with an 80 grit and work up to a 200 grit sandpaper. After sanding, the plywood should be smooth, and the surface will be ready for painting.

Step 11.  Painting The Plywood

The final step in waterproofing plywood is to paint on a few coats of paint. It should take up to four coats of color paint to shield the epoxy from the sun. Use high-quality latex waterproof paint and let the paint dry after every coat. The paint will give a beautiful finish to the wood and add that extra layer of protection from the elements.

Method 2. Waterproofing Plywood For A Boat With Latex Based Paint

Waterproofing plywood with latex-based paint is less reliable than using epoxy; thus, it will be adequate for boats that are not exposed to water for prolonged periods. Latex-based paint will waterproof plywood, but it will need to be painted more regularly.

When choosing a quality latex-based paint, there are three types for you to choose from, gloss, matt, and semi-gloss. The gloss paint is the most durable, but it will display the imperfection in the wood. In contrast, the matt and semi-gloss hide imperfections better but are not as durable.

Always follow the instructions from the paint manufacturer as brands will differ in mixing, painting, and drying time.

Set up a proper working environment and have the following materials at hand.

• Brush or roller
• Latex-Based Paint
• Latex Paint Primer
• Paint sticks
• Sanding paper (80 grit)

Step 2. Preparing The Plywood

Wipe the plywood down with a cloth or paper towel and acetone to remove all dirt and debris. The acetone will aid in cleaning the dirt and removing any surface moisture from the plywood. Let the wood dry for a minute or two.

Step 3. Sand The Plywood

Use 80 grit sandpaper and sand the plywood till the imperfections have been removed and the surface is smooth to the touch. It is recommended to use a dust-mask while sanding plywood as the dust could be harmful.

Step 4. Apply Primer To The Plywood

Latex-based paint will require a primer to be painted on the wood. The primer serves many benefits, such as better adhesive for the paint, more durability, and a smooth finish after painting.

Using a quality latex-based primer, paint a thin layer of primer onto the wood with a paintbrush. Make sure to cover the entire piece of plywood and allow the primer to dry for about 1 hour.

Step 5. Sanding And Applying The Second Coat Of Primer

When the first coat of latex primer is dry, lightly sand the plywood to see if any imperfections are showing through. Rub the plywood down with a tack cloth and paint on the second coat of primer by repeating step 4.

Step 6. Applying The Latex-Based Paint

Use a paint roller or brush and spread a thin layer of paint onto the primed plywood. Avoid too much paint on the brush or roller, as it will cause the paint to drip and pool.

After the first coat, let the paint dry for two to three hours before applying the second coat of paint. It is highly recommended to apply a minimum of two coats but feel free to apply as many coats as needed for the application.

The plywood will be protected when the paint is dry, but the latex-based paint will need to be reapplied in roughly 24 months to ensure its effectiveness.

Marine Grade Plywood

It is not easy to distinguish between regular plywood and marine plywood. Here are a few traits of marine plywood.

• Marine plywood has a smoother finish than regular plywood.
• Marine plywood is heavier
• Fewer visible knots in the wood surface
• It has hardwood veneers
• Less bending capacity
• Marine plywood has up to 10 layers

Marine Plywood Durability

Marine plywood is much more durable than ordinary plywood. Marine plywood can last up to 25 years or longer with regular maintenance. The key to a long life span is waterproofing regularly and keeping it out of the elements as much as possible.

Why Sealing Boat Plywood Is Important

An experienced boater can contest that the marine environment is entirely different from the norm, and the plywood will have to stand up to the following:

• The Sun : The UV Rays from the sun can damage the wood on the boat, and due to the nature of boating, it will spend many hours in the blistering sun.
• Water: Water soaks into the wood and causes it to rot, this is a fact, but it can be prolonged and even prevented. Sealing the wood with epoxy can keep the wood dry and structurally strong.
• Humidity: The water in the air can do the same amount of damage to wood. Combining the heat from the sun and the moisture in the air is a perfect recipe to have water end up in all the areas you least expect. This is the reason for waterproofing all the wood to some degree.

It is important that you do not just purchase any sealant, but rather one designed with specific waterproofing properties for the marine environment.

Using Epoxy for Waterproofing And Boat Repairs

Epoxy resin is one of the most adaptable materials that can be used in boat repair, building, and waterproofing. Epoxy is often used to repair Gelcoat cracks, new bulkhead installations, and any other boatyard repair project that might need to be completed.

Uses for Epoxy Resin

Epoxy resin uses fall into a few categories:

• Coating: Apply one or more thin coats of epoxy to seal the surface or prepare the surface for paint or use it to reinforce layers of fiberglass.
• Bonding: Using the epoxy as a glue, generally with some filler to fill gaps between the surfaces or attach items.
• Laminating: Multiple layers of wood are bonded together to create a thicker solid structure.
• Fairing: Thickened resin can be used to fill holes and depressions so that the surface can be sanded and smoothed.

The Pros And Cons Of Latex Base Paint

The following are the pros and cons of latex-based paints for boats.

Pros of Latex-Based Paint

• Inexpensive
• Greater availability and variety
• Non-flammable and non-toxic
• Easy application
• Easy clean-up

Cons Of Latex-Based Paint

• Swells and cracks if painted on wood surfaces
• Takes a long time to cure and can crack on rough surfaces
• Won’t adhere to dirty surfaces
• Not for use on things being touched or moved.

Waterproofing plywood for a boat can be made easy by following the steps provided in this article. Whether you decide to use the first or second method is up to you as they both have their strengths. Always follow the paint or epoxy manufacture instructions as each will differ.

Ensure that the plywood you are using for the boat is marine-grade plywood and not standard plywood, as they each have different properties. So now that the plywood is treated, it’s time to continue with the project and set sail.

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5 Tips for Painting Marine Plywood

• Written by Chris Nickson on Jun 30, 2010 To ensure our content is always up-to-date with current information, best practices, and professional advice, articles are routinely reviewed by industry experts with years of hands-on experience. Reviewed by KC Morgan on Jun 02, 2023

Marine plywood is a particular variety of plywood that’s been treated to withstand moisture . As the name implies, it’s often used on boats and other items that are in frequent contact with water. Whether it’s for marine use or exterior use, marine plywood still needs to be painted in order to be fully durable, and painting it properly can require some know-how.

Before applying any kind of paint, you need to sand marine plywood as you would any other type. Do this to remove imperfections in the wood and to help the primer adhere more easily to the surface. Make sure you wipe off all the sawdust after you’ve finished. A damp cloth is good for this (allow the wood to dry in this case before you proceed) or you can use a tack cloth for the job.

If you’re using marine plywood where it’s likely to come in contact with water, such as on the exterior of a house, you should use latex-based paints. Unlike oil-based paints, they’re very durable and will expand and contract with the wood so they won’t crack.

You need to apply a thin coat of latex-based primer to the wood first. Give it plenty of time to dry and then sand it down lightly. You should only sand just enough to roughen the surface a little. Doing this will let the paint make a good strong bond with the primer. Remove all the dust with a tack cloth again before you go ahead and begin to paint.

Choose Your Paint Carefully

What type of finish paint you use on the marine plywood is up to you, and how you’ll be using the wood. The gloss gives the hardest finish of all types, but the problem is that it also shows imperfections easily. The most utilitarian choice is semi-gloss. The hardness of the finish is virtually as good as gloss and it will cover any remaining imperfections in the wood. Just be sure to use latex-based paint over the latex primer.

Use the Right Technique

Start by putting on a thin coat of paint. There’s no need to sand between coats. Just allow it to dry, which should only take between two hours and three hours, and then apply another thin coat. In most cases, two coats of paint should be adequate, but you can add an extra coat for greater protection if you desire.

You can spray the paint on, but you’ll achieve a better thin coverage if you use either a brush or a roller to apply it. Start at the top, working from one side to the other. This will allow you to work in any drips as you move down the sheet of plywood. Don’t put too much paint on your brush before you begin painting; that’s just an invitation for excessive dripping.

Renew as Needed

The paint should be good for a few years, although this depends on which use the wood is put to. The greater its exposure to abuse and the elements, the more regularly it will need to be renewed. You should inspect the marine plywood regularly for wear.

Marine Plywood Painting FAQ

What is the best paint for marine plywood.

There are many different types of paint that are designed for all kinds of uses. You will find paint that is optimized for outdoor use, as well as paint that's made to be ideal for use inside.

Semi-gloss paint works well for plywood, though you can use a variety of paints on this material. Sand the wood very well before you do any painting on it.

Do I need to prime plywood before painting?

Applying primer before you paint plywood will give you the best results. Sand the plywood well before applying a thin, smooth coat of primer.

Allow the primer to dry completely before you paint.

How do you make plywood look good painted?

To give plywood a nice, finished look after it's painted, spend some time prepping it first. Fill all little dents and holes with wood filler to get started.

Use joint compound on all the seams to create a smooth look. After it dries, sand down the wood filer ad the joint compound to create a smooth finish.

Do another coat of compound and repeat the drying and sanding process before you prime the wood. Use at least two coats of paint to get a nice, even layer of coverage.

How long will painted marine plywood last?

Marine plywood is a highly durable material, even when unpainted. When it's painted and even when exposed to the outdoors, marine plywood can last anywhere from 30 to 50 years.

Should I seal marine grade plywood?

Marine-grade plywood is optimized for use outdoors but sealing the plywood can add still more durability. To seal the material, cover it with a clear epoxy.

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