Varnishes used for wood

In this article, we will explore the different types of varnishes commonly used for wood. Varnish is a popular choice for wood finishing as it provides protection and enhances the natural beauty of the wood. 

What is varnish?

Varnish is a type of clear coating that is applied to various surfaces, such as wood, metal, or even paintings, to provide a protective and decorative finish. It is a transparent or translucent liquid that dries to form a hard, durable, and glossy film.

The primary purpose of varnish is to protect the underlying surface from damage, such as scratches, moisture, UV radiation, and general wear and tear. It acts as a barrier, shielding the material from environmental factors that can degrade its appearance and structural integrity.

In addition to protection, varnish also enhances the aesthetic appeal of the surface by adding a glossy or satin sheen. It can bring out the natural beauty of wood grain, deepen colors, and provide a smooth and polished finish. Varnish can be applied in various thicknesses, depending on the desired level of gloss and the specific requirements of the project.

Varnish typically consists of a mixture of resins, solvents, and drying agents. The resins form the protective film when the varnish dries, while the solvents help to dissolve the resins and make the varnish easier to apply. The drying agents speed up the drying process, allowing the varnish to cure and harden.

Types of Varnish used for Wood

There are several types of varnish that are commonly used for wood. Here are some of the most popular ones:

Spirit Varnish

Varnishes that use spirit as a solvent, such as spirited varnish or French-Polish, involve dissolving shellac in spirit and applying it in thin layers. These varnishes provide a translucent finish that allows the natural grains of the wood to show through.

Spirit varnishes

However, it’s important to note that spirit varnishes are not suitable for outdoor use because they do not weather well. They are more commonly used for polishing indoor woodwork or furniture that is not exposed to the elements. For outdoor furniture or woodwork that will be exposed to weather conditions, it is recommended to use varnishes specifically designed for exterior use, as they offer better protection against moisture, UV rays, and other weather-related factors.

Acrylic Varnish

Acrylic varnish is a type of varnish that is quick-drying and non-toxic, as it is water-based. It offers good resistance against ultraviolet rays, making it suitable for both indoor and outdoor surfaces exposed to sunlight.

One of the advantages of acrylic varnish is its versatility. It can seal wood and other materials effectively, making it a popular choice for various applications. Unlike some other types of varnishes, acrylic varnishes are clear, highly transparent, and do not tend to penetrate the wood deeply.

Acrylic varnishes

Another benefit of acrylic varnishes is that they are easy to clean up since they are water-based. This makes them user-friendly and convenient to work with. However, it’s worth noting that acrylic varnishes may not spread as uniformly as other varnishes, which can sometimes result in uneven application.

Acrylic varnishes are typically available in different finishes, including sheen, satin, and matte. This allows you to choose the desired level of shine or gloss for your project, depending on your preferences and the aesthetic you want to achieve.

Polyurethane Varnish

Polyurethane varnish is a type of varnish that is known for providing a hard and durable surface. It is commonly used for areas that will experience a lot of wear and tear, such as floors. One of the key advantages of polyurethane varnish is its heat resistance, making it suitable for surfaces that may come into contact with hot objects.

Polyurethane varnish creates a clear and tough finish, and it is available in different finishes, including gloss, satin, and matte. The varnish does not tend to penetrate the wood deeply, so it is often recommended to prime the wood with an oil-based varnish or a thin shellac solution before applying the polyurethane varnish.

Polyurethane Varnishes

It’s important to note that oil-based varnishes should not be applied on top of polyurethane varnish, as they will not bond properly. Polyurethane varnishes have excellent hardness and durability and are resistant to spills of mild acids, solvents, and other chemicals.

However, one limitation of polyurethane varnishes is that they are not resistant to UV light from the sun. If you plan to use polyurethane varnish on an outdoor project, it is advisable to look for a product with added UV protection. Without UV protection, the varnish may deteriorate quickly when exposed to sunlight.

Yacht Varnish

Yacht varnish, also known as marine varnish, was initially developed for use on boats to prevent water from penetrating the wood. Its primary purpose is to provide a highly flexible coating that can withstand the bending and flexing of the wood under the strain of the sea. This flexibility is crucial because rigid and inflexible varnishes may crack, allowing water to seep into the wood.

Yacht Varnish

Traditionally, yacht varnishes had a low gloss finish, as their appearance was considered a secondary feature. They also offered limited UV protection. However, modern yacht varnishes now often feature a high gloss finish, achieved through the use of Tung oil and phenolic resins. This enhances the aesthetic appeal of the varnish while still maintaining its flexibility and water resistance.

Yacht varnishes are ideal for use on exterior timber surfaces, providing protection against moisture and the elements. However, they are not suitable for surfaces that will be walked on, as they may not provide sufficient durability under heavy foot traffic.

Oil Varnish

Oil varnishes are created by dissolving hard resins, such as amber or copal, in oil. They have a slower drying time compared to other varnishes but are known for being the hardest and most durable.

Alkyd Varnish

Due to their durability, oil varnishes are well-suited for use on exposed surfaces that require frequent cleaning or polishing. They are also commonly used for superior quality work where a high level of durability and longevity is desired.

The slow drying time of oil varnishes allows for a smoother and more even application, reducing the risk of brush marks or uneven coverage. However, it is important to note that the longer drying time can require more patience during the application process.

Alkyd Varnish

Alkyd varnish is a versatile type of varnish that can be used on both exterior and interior surfaces. One of the main advantages of using alkyd varnish is its ability to provide excellent protection against various elements.

Oil varnish

Alkyd varnish offers protection against UV damage, which can cause fading and discoloration of the wood over time. It also helps to shield the surface from temperature variations, which can cause the wood to expand and contract, leading to cracks and warping. Additionally, alkyd varnish provides a barrier against water seepage, helping to prevent moisture damage to the wood.

In addition to its protective qualities, alkyd varnish has the ability to enhance the natural colors and grain of the wood. This can result in a more visually appealing finish, bringing out the beauty of the wood’s natural characteristics. Alkyd varnish is typically clear, allowing the natural color of the wood to shine through.

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How to Apply Varnish to Wood?

Applying varnish to wood is a straightforward process. Here are the steps to follow:

Prepare the surface

Ensure that the wood surface is clean, dry, and free from any dust or debris. Sand the wood lightly to smooth out any rough areas or imperfections.

Choose the right varnish

Select a varnish that is suitable for your project. Consider factors such as the type of wood, desired finish (glossy, satin, or matte), and the level of protection required.

Stir the varnish

Before applying, stir the varnish thoroughly to ensure an even consistency. Avoid shaking the can, as it can introduce air bubbles.

Apply the first coat

Use a brush, foam applicator, or cloth to apply an even coat of varnish to the wood surface. Work in the direction of the wood grain for a smoother finish. Apply the varnish evenly, avoiding excessive brush strokes or pooling.

Allow drying time

Follow the manufacturer’s instructions for the recommended drying time between coats. This typically ranges from a few hours to overnight, depending on the varnish type.

Sand between coats

Once the first coat is dry, lightly sand the surface with fine-grit sandpaper to smooth out any imperfections. Wipe away any dust before applying subsequent coats.

Apply additional coats

Repeat the process of applying varnish and allowing it to dry between coats. The number of coats will depend on the desired level of protection and finish. Typically, 2-3 coats are recommended.

Finishing touches

After the final coat has dried, inspect the surface for any imperfections or rough areas. Lightly sand if necessary, and wipe away any dust before applying a final coat for a smooth finish.

Allow for curing time

Once all coats have been applied, allow the varnish to cure fully according to the manufacturer’s instructions. This can take several days or longer, depending on the varnish type.

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