After staining or painting furniture, DIYers are advised to apply a few coats of wood sealer to protect the surface from water damage, scratches, UV exposure, and dents.
But with different types of wood sealers out there, it can be tricky to decide on which to go for. This article reveals the different types of wood sealers, how they are made, when to use them, and their pros and cons. Let’s dive in.
What are Wood Sealers?
Wood sealers are topcoats that are used to protect the finish on the wood. Sealers can also be applied on bare wood if the natural grain and look of the wood are to be maintained.
Sealers are either water-based or oil-based but they are often reinforced with additives like UV blockers, plasticizers, and thinning agents that give them unique properties.
Most wood sealers are water-resistant, mold-resistant, UV-resistant, and they often have a high-gloss finish. The additives in the sealer make them extra tough to withstand damages that the wood or finish would otherwise have been exposed to.
Here are the different types of it:
Read More: How To Seal Wood For Outdoor Wood?
Polyurethane is a very popular wood sealer thanks to its protective qualities and water resistance. There are two types of polyurethane sealers; water-based and oil-based polyurethane.
Water-based polyurethane is preferred because of its quick drying time and non-yellowing finish. Oil-based polyurethane takes a bit longer to dry and tends to yellow after a while.
When applied, polyurethane sits on the top layer or finish on the wood to form an ultra-thick film that withstands dents, scratches, and moisture.
Polyurethane is a synthetic plastic in liquid form. It is made through a chemical reaction between a base (polyols) and hardener (isocyanate compounds).
The solvent or carrier in polyurethane is either water or synthetic oils. Polyurethane also contains other additives that make the finish strong.
You can use polyurethane sealer indoors and outdoors. For outdoor uses, ensure to use exterior-grade polyurethane. Exterior grade polyurethane has additives in its formula like UV blockers to make it weather-resistant and tough enough to withstand the harsh exterior environment.
You can also use it indoors but it’s advised to use the water-based type. Polyurethane should be used to protect finishes from scratches, pet claw marks, and dents.
You can also use it for high-traffic surfaces such as countertops, tabletops, and floors. Since its finish is elastic, it can contract and expands based on temperature changes.
- Water-resistant and can protect wooden surfaces from water damage.
- Exterior-grade polyurethane is reinforced with UV-blocking additives.
- Easy to apply – You can brush or spray on poly.
- Weather-resistant. It protects wood from warping, corrosion, and weathering.
- It is available in different finishes from satin to high gloss.
- It is elastic and can withstand temperature changes without cracking or peeling.
- Polyurethane can be mixed with latex paint to give the finish color.
- Oil-based polyurethane is known to yellow over time due to the presence of synthetic oils in its formula.
Lacquer is a clear and synthetic finish popular for its high-gloss sheen and wood protection. The finish is applied using a high-volume low-pressure (HVLP) sprayer because it is very thin.
It dries fast and forms a durable layer on wood when dry. It’s recommended for beginners since you can easily repair mistakes by sanding or applying another coat.
Each successive coat of it dissolves into the existing coat to form a very strong finish. Lacquer is your finish if you want to showcase the natural beauty of the wood.
Lacquer sealer has been around for centuries and traditional lacquer that emerged from Asia was made from the sap of the ‘Toxicodendron Vernicifluum” tree, also known as the Chinese Lacquer tree. However, modern lacquer has a different formula.
Today, lacquer is made from acrylic resin dissolved in solvents. This is it has a very thin nature. When applied, the solvents evaporate quickly leaving the finish to harden and form a tough layer on the surface.
You should use lacquer when working on high-traffic surfaces like floors and countertops. This is because it is tough and durable so it can withstand high-traffic and consistent use.
You should also use it if you want to showcase the natural beauty of the wood since it’s a transparent finish.
- Easy to apply. As long as you have an HVLP paint sprayer, you can apply up to 4 coats in one afternoon.
- It dries quickly and is easy to repair.
- Tough and durable finish.
- Water-resistant and can also repel other household liquids including alcohol.
- It produces a smooth finish when dry.
- Its finish can get discolored after some time. You can sand and reapply the finish when this happens.
Wax sealer is a paste-like natural finish that has been used on wood for several decades. It is popular for the dark tone it leaves on wood. If you want your finished wood to have a darker shade, wax is your sealer.
Its thick texture allows it to block light rays from reflecting on the finish. This gives it a darker appearance. It also protects wood from scratches and dents making it a popular finish on wooden floors. The finish is shiny and eco-friendly so it’s safe for indoor use.
Traditionally, wax is made by mixing beeswax with oil, usually a plant-based oil like walnut oil, linseed oil, coconut oil, or olive oil.
The combination produces a thick paste-like gel that can be massaged directly on wooden surfaces. This formula is great but it produces a finish that takes some time to apply and several days to fully dry.
So, today many manufacturers are using synthetic products to produce liquid wax (not paste) that is easier to apply and dries faster.
You can use wax on indoor wooden surfaces. It’s also a great finish on wooden floors but it’s not ideal for vinyl flooring.
You should use it when you want a deeper shade on your finished wood. Its thick nature can help alter the look or finish of the wood to a deeper tone.
Wax is also an amazing choice for decorative furniture. The bright sheen of its finish will give your wall frames a beautiful sheen that will come alive when exposed to light.
- It protects wood from wear and tear associated with high traffic and weight.
- It gives a reflective finish that is perfect for decorative pieces.
- It is water-resistant and protects wood from mold growth.
Cons of Wax
- You need to hand-polish it which can be time-consuming, especially on large surfaces like floors.
- It can take a long time to fully dry especially when applied in cold temperatures like during the winter season.
- It is difficult to remove from wood so you should be sure about it before using it because there is no turning back after.
Varnish is one of the most popular sealers because many manufacturers wrongly term their products “Varnish”. Varnish actually refers to an oil-based sealer that dries through oxidization (reaction to oxygen). There are different types of varnishes, each suited for a particular use.
Spar varnish is used on sea vessels and high-moisture areas because it has terrific water resistance and can even be described as waterproof.
Exterior-grade varnish is used on outdoor furniture and building exteriors because it is weather-resistant and doesn’t degrade when exposed to UV rays.
Alkyd varnish is a versatile finish that has been altered with vegetable oils to make it dry faster and give it a clear finish. Other types include spirit, oil, and acrylic varnish.
The composition of varnish is not specific since there are different types of it. However, the main ingredients found in virtually all types include resins, usually alkyd resins, and a solvent or carrier, usually an oil-based solvent.
It’s also common for varnish to contain dye or pigments. This is often done to give the finish color when it dries. Since the product is oil-based, it takes a while to dry because the solvent (or oil) needs to evaporate first.
You can use it indoors and outdoors but most people use it on exterior wood thanks to its weather-resistant properties. Varnish is water-resistant and UV-resistant so it can protect outdoor furniture from weathering, warping, and cracking.
- Durable and it offers excellent wood protection.
- Water-resistant and commonly used on surfaces that are exposed to moisture to protect them from water damage.
- Flexible and can withstand changes in temperature without cracking or splitting.
- Great for outdoor use because it is UV-resistant.
- It has a honey tone that enhances the texture and finish of your wooden surface.
- It can be used on finished wood since it doesn’t penetrate wood grain.
- It takes several hours to dry and even more to fully cure.
- It can be difficult to apply. It’s common for bubbles to form on the surface during application. Also, you need to thin and sand the product before and during application.
Shellac is a natural sealer known for its beautiful finish and ability to blend well with other colors and paints. If you want to tint your sealer, professional painters would advise you to go for shellac.
The finish is high-gloss and it’s mildly durable when compared to other sealers.
Shellac is a natural sealer gotten from the secretion of the female Lac beetle (Kerria Lacca). The secretion is collected, processed, and then dissolved in a solvent, usually, an alcohol-based solvent like ethanol to make it easy to apply to wooden surfaces.
You can use shellac on indoor furniture and when working on decorative furniture like vases and wall frames. You can also use shellac directly over stained or painted wood.
Do not use shellac on tabletops or countertops because it has low heat resistance. Also, the finish is easily dissolved when exposed to alcohol and beverages.
- Blends well with other colors and paints, especially latex paints.
- The finish is beautiful and ideal for decorative surfaces.
- It dries fast and is easy to apply.
- You can use it as a base coat for most sealers including varnish and polyurethane.
- Shellac maintains its look and doesn’t yellow over time.
- It can be dissolved easily, especially if exposed to alcohol.
- It isn’t ideal for exterior surfaces because it isn’t a durable finish.
In summary, wood sealers are used to protect finished wood and, in some cases, bare wood. Its tough finish protects the wood from water damage, cracks, dents, and deterioration.
You should ensure the sealer you buy is suitable for the surface you want to use it on. For exterior surfaces, exterior-grade polyurethane works fine. For interior surfaces, you can go for shellac. If you want a transparent finish, you can go with lacquer and for a dark finish, you should go with a wax sealer.
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,