When it comes to interior decoration and architecture, nothing beats the elegance and timelessness of wood. Whether it is used for furniture, flooring, or front porches, wood has the uncanny ability to infuse character into a home.
Unfortunately, just like all things natural, wood is prone to decay. The only way to protect wooden surfaces for long-term use is by applying wood finishes.
In this article, we will be discussing the different types of wood finishes, how to use them and why.
What is a Wood Finish?
Wood finish is any chemical substance applied on the surface of wood to provide a protective layer. Depending on the type of finish, it can protect the wooden object from drying, cracking, fading, or rotting. They may also protect wood from the adverse effects of the weather, including UV light and humidity, water damage, and mold.
Besides environmental impacts, wood finishes can also protect wood from scratches, stains, and other abuses humans and animals inflict on furniture daily.
Wood finishes, also known as wood furniture finishes, can be applied to bare or stained wood. Some finishes can also be applied on top of others.
In order to maximize the benefits of a wood finish, you have to choose the right one per project, and that begins by adequately understanding the different types of wood finishes.
Types of Wood Finishes
There are two main types of wood finish:
- Penetrating finish
- Surface finish
As their names imply, penetrating finish goes into the wood, while surface stays on top of the wood.
Of course, some finishes have a combination of the two, but each one will still be classed underneath one of the two broad groups.
Under each of these types is a range of options, each with its unique pros and cons.
Penetrating Finishes
Penetrating finishes have been used for thousands of years to protect most of the antique furniture we have today. These products are usually made from natural oils, which is why they are absorbed by wood easily and offer excellent protection against the forces of nature.
A lot of research has gone into improving the penetrative finishes we now use today to make them easier to apply and more durable. This type of finish is highly coveted, especially for high-end furniture, because it yields a more natural look and feel. They can also be applied quickly and are generally eco-friendly.
Some of the most popular ones are:
1. Tung Oil
Tung oil is one of the oldest finishes in the world and is derived from the seed of the tung tree, which is native to China. As a result, it is also called Chinese wood oil. Nowadays, tung trees are also grown in South America.
Tung oil is environmentally friendly and non-toxic during and after application. In addition, it is a non-darkening oil, so when it penetrates the grain, it brings out the natural beauty of the wood.
Unlike many other oil-based finishes, tung oil dries clear and does not yellow as much over time, which is why it is highly regarded in the furniture industry. However, it is rare to find 100% pure tung oil, as it is very expensive and takes a long time to dry.
Fast facts:
- Ease of application: Moderate
- Cleaning and thinning: Mineral Spirits or Paint Thinner
- Sheen: Pure tung oil has a low sheen, but resin-modified tung oil options are sold in satin, semi-gloss, and gloss
- Solvent: None
- Recommended use: Household furniture, boat decks
- Unique Property: It is environmentally friendly and has no VOC emissions
- Application tools: Cloth or brush
2. Linseed Oil
Another penetrating finish that has been used for centuries is linseed oil. This natural oil is derived from flaxseed, hence why it is also known as flaxseed oil.
Linseed oil is one of the most versatile ingredients in the construction industry, as it can be used on its own or in other finishes such as varnish, stains, and paints.
To get the most out of linseed oil, it needs to be applied directly on bare wood or wood finished with other oils. Otherwise, it won’t penetrate the surface.
One note of warning is that linseed oil is highly flammable, and papers soaked in it might spontaneously combust if not disposed of properly. Linseed oil can also go rancid.
Fast facts:
- Ease of application: Easy
- Cleaning and thinning: Mineral Spirits or Paint Thinner
- Sheen: Low sheen (satin)
- Solvent: Non.
- Recommended use: Gunstocks, furniture, surfboards, and furniture
- Unique Property: It can be used with different oils, and it is eco-friendly
3. Danish Oil
Now, we come to the first factory-made penetrating finish. Once a popular fixture in Scandinavian furniture makers in the 20th Century, Danish oil is made by mixing a natural oil with varnish and thinner. The varnish may be exterior varnish or polyurethane, while the oil is usually boiled linseed oil or tung oil.
As a result, Danish oil provides the wood-penetrating benefits of oil and the enhanced protection and durability of varnish. Just like linseed and tung oil, it is best to apply it on bare wood or previously oiled surfaces.
Fast facts:
- Ease of application: Easy
- Cleaning and thinning: Mineral Spirits or Paint Thinner
- Sheen: Satin finish
- Solvent: None
- Recommended use: Wooden utensils and worktops
- Unique Property: It acts as both a penetrative finish and a surface finish
4. Cedar Oil
As you have rightly guessed, cedar oil or cedarwood oil is derived from the cedarwood tree. The needles, leaves, bark, and berries of some conifer species produce this indispensable oil that is useful in both the woodworking industry and the healthcare industry.
Besides prolonging the life of wooden furniture, cedar oil has the distinct advantage of being a natural insect repellent. The oil also has a sweet, woody aroma that is used in aromatherapy.
Cedar oil is not as popular as any of the other products on our list as a wood finish, as it is more revered for its medicinal uses.
Fast facts:
- Ease of application: Easy
- Cleaning and thinning: Mineral Spirits or Paint Thinner
- Sheen: Low sheen
- Solvent: None
- Recommended use: Furniture and floor polishing
- Unique Property: It can resist or even kill some insects
Surface Finishes
As mentioned earlier, surface finishes provide a protective coat that sits on the wood, almost like a film of plastic. In general, they last longer, offer better protection from the weather and moisture but require more skill to apply.
1. Shellac
Shellac is an amber-colored finish derived from the excrement of the female lac bug, found on trees in Thailand, Burma, and India. For it to become a workable wood finish, these secretions are mixed with alcohol.
The result is a product that has been very popular for centuries because it yields a smooth, hard, and high gloss. Shellac is also durable and resistant to UV light, so it doesn’t darken over time.
Shellac gives a gorgeous finish that is desirable in high-end furniture. However, it is brittle, susceptible to heat, and can be stained by household chemicals. It can also be dissolved with alcohol, so it should not be used in kitchens or any objects likely to be handled a lot.
Fast facts:
- Ease of application: Easy
- Cleaning and thinning: Denatured alcohol
- Sheen: Glossy
- Solvent: Alcohol
- Recommended use: Fine furniture
- Unique Property: It can be used as a protective coat on non-wood items and comes in a variety of colors
2. Lacquer
Lacquer is a popular finish used on cabinets and a lot of high-end furniture. Despite being a very thin finish, it dries hard and is very durable. However, to get that finish, you require a fair bit of skill. The best way to apply lacquer is with a high-volume, low-presser (HVLP) sprayer.
Lacquer is made by combining different solvents and resins. Even though it was initially made from the secretions of the lac bug, it is no longer necessarily the case. Given the wide range of manufacturers, one type of lacquer could be drastically different from another.
Given the high quantity of volatile organic compounds (VOCs) released during application, lacquer is not environmentally friendly. As a result, we are seeing more water-based lacquers, which some argue shouldn’t be called lacquer because they can’t be dissolved by lacquer thinner.
Fast facts:
- Ease of application: Difficult
- Cleaning and thinning: Lacquer Thinner
- Sheen: Low-Satin, Satin, Semi-Gloss, and Gloss
- Solvent: Lacquer Thinner
- Recommended use: Cabinets, commercial furniture, and fibreboard
- Unique Property: Best applied with a High Volume Low Pressure (HVLP) Sprayer
- Drawback: It yellows over the years, so it is not ideal for light-colored woods
3. Varnish
Now, we come to the most confusing wood finish of them all. Depending on who you ask, lacquer, shellac, and polyurethane are all varnish. According to Britannica, Varnish is a liquid coating material that contains a resin and dries to a hard, transparent film. As you can see, this description fits all of the others.
However, for the sake of simplicity, we are going to use this term to refer to spar varnish or marine varnish. This is the most durable type of wood finish there is and is best suited for outdoor use and on ships.
Varnish is an excellent finish even for indoor use, but it can be tricky to apply and, if it’s not done correctly, is prone to cracking, bubbling, and peeling.
Fast facts:
- Ease of application: Difficult
- Cleaning and thinning: Mineral Spirits or Paint Thinner
- Sheen: Matte, Semi-Gloss and High-Gloss
- Solvent: None
- Recommended use: Decks and outdoor furniture
- Unique Property: Varnish penetrates the wood instead of sitting on it like a plastic coat, which makes it highly durable
4. Wax
Long before Mr. Miyagi taught us to wax on and wax off, furniture-makers had been using wax to add a finishing touch to wood. Just like with cars, wax is used to revive dull-looking sheens, add an extra layer of protection and prevent the surface from cracking.
Wax is usually derived from animals or vegetables. The most common type of animal wax is beeswax, while carnauba wax is the primary vegetable derivative.
Unlike the previous finishes, wax should not be used on bare wood. While it may provide a bit of scratch resistance, it is not waterproof and needs to be reapplied often. On the other hand, wax does a great job of hiding any scuff marks on other protective coats and can delay water absorption. That is why it is the one finish you should always have lying around, even if it isn’t your primary option.
Fast facts:
- Ease of application: Easy
- Cleaning and thinning: Mineral Spirits or Paint Thinner
- Sheen: Matte to Satin
- Solvent: Turpentine
- Recommended use: Picture frames, furniture, and flooring
- Unique Property: It goes on nearly every other type of finish to add extra protection and durability
5. Polyurethane
Polyurethane is a durable, water-resistant finish that dries very hard. The two main types of polyurethane are oil-based and water-based. While they both do the same thing, each one has its unique advantages and disadvantages.
Oil-based polyurethane gives a warm glow to wood, and it yellows over time. Water-based poly dries very clear and remains clear. Both can be used to protect wooden surfaces for over a decade when applied and maintained correctly.
Polyurethane is arguably the most versatile finish, as it can be used for interior and exterior projects and high-traffic areas, and it is scratch and stain-resistant. The main drawback is that it can be challenging to repair when damaged. However, it will take a lot to damage polyurethane.
Fast facts:
- Ease of application: Moderate
- Cleaning and thinning: Mineral spirits or paint thinner
- Sheen: Matte, Satin, Semi-Gloss, and Gloss
- Solvent: None (it can only be removed by sanding or scraping)
- Recommended use: Floors, tables, stairs, railings, and fences
- Unique Property: Lasts for years without needing a recoat
6. Wood Dye
When you want to change the color of wood, you have two options: wood dye or wood stain. Wood dye is the less common of the two, as it isn’t technically a finish. Also, wood dye penetrates the wood, and it doesn’t provide any protection.
However, wood dye can be mixed with shellac, lacquer, or water-based finishes to create a stunning and unique outlook. Even though it offers no practical benefit on its own, it can be used intelligently to provide colorful surfaces as an alternative to paint.
Wood dye usually comes as either a powder or liquid concentrate. You can also make your own dye at home using ingredients such as turmeric and beetroot.
Once mixed in with other finishes, it simply takes on the properties of whatever it is put in.
7. Stain
A stain does the same thing as a dye in that it changes the color of the wood. However, it does it differently, and it has intrinsic properties. Wood stain is sometimes referred to as paint because they’re both made of pigment, a solvent/carrier, and a binder.
Wood stain can either be a penetrating finish or a surface finish.
This type of finish does a great job of bringing out the beauty of the grain and is great before you apply a clear coat over it. While mixing stain with polyurethane, the poly is usually applied over the dry stain for a more natural look.
Stains come in a near-infinite range of colors and can be oil-based, water-based, or gel stains.
Fast facts:
- Ease of application: Easy
- Cleaning and thinning: Mineral spirits or paint thinner
- Sheen: Low sheen
- Solvent: None
- Recommended use: Wood furniture, floors, doors
- Unique Property: It should only be applied on bare wood
8. Paint
Here is a product that needs no introduction. While many people like wood for its natural look, some pieces of wood need to be beautified or hidden, and that’s where paint comes in.
Even though paint is a durable and easy-to-use finish, you can also apply other surfaces on top of it, such as polyurethane. Paint also provides more color options than stains and offers decent protection against the forces of nature.
Fast facts:
- Ease of application: Easy
- Cleaning and thinning: Mineral spirits or paint thinner
- Sheen: Glossy to high gloss
- Solvent: methylene chloride, acetone, isopropyl alcohol, and many others
- Recommended use: Wood furniture, walls, doors, and decorative pieces
- Unique Property: It is by far the most popular finish ever
Factors to Consider When Choosing a Wood Finish
When you’re new to woodworking, one of the hardest things to do is pick a finish. With so many options to choose from, it can be tricky narrowing down your options. Over time you will have a go-to finish, but initially, it will take some trial and error.
However, if you’re ready to waste money on costly mistakes and want to get it right the first time, here is a simple process that will help you choose the right wood finish.
1. Project Type
The first thing you need to think of when choosing a wood finish is the project you are creating. That means you need to consider the type of wood you’re using. For example, light-colored woods do better with water-based finishes or really clear coats because oil-based finishes tend to yellow.
It would help if you also thought about where the project will be located and who will be using it. If you’re building or refinishing floors, for example, where will the floor be located?
A walkway or kitchen floor will see more traffic than an office floor, so the former will need a more durable finish. If it will be used by kids, you probably won’t want a glossy finish, and you need it to be waterproof.
2. Durability
When you establish where you are going to place the project and who will be using it, the second natural step is to decide on the level of durability you need.
Things you need to consider are how resistant it is to water, heat, scratches, stains, household chemical spills, and heavy objects. If the project will be used outdoors, you also need to consider how well it handles UV lights, humidity, and changing weather conditions.
Even though varnish is the toughest and most durable finish, you may not need it in all scenarios. It is very effective for exterior use, but it might be overkill for some interior applications.
For example, if you are designing a cabinet for adults, you may not need heat and water resistance. You also could get away with a finish that isn’t as scratch-resistant because you don’t expect a lot of those over the years, so a nice shellac finish might be adequate.
Once you have ascertained the level of protection you need, you are free to consider more aesthetic options.
3. Appearance
As important as appearance is, it has to sit behind durability and purpose. Lacquer and shellac arguably give the most gorgeous finish. They yield a nice, glossy coat that brings out the beauty of the wood without looking like a film of plastic, as polyurethane does.
However, they are not as strong or water-resistant as polyurethane or varnish, so it is important to get the order right.
If you want a truly natural look, then your best bet will be a penetrating finish. But, of course, you also need to consider not just how it appears today but how it will look as it ages. For example, linseed oil is notorious for getting darker, while tung oil doesn’t.
Then again, if you are not too happy with the appearance, you can always put some wax on it.
4. Color
It is impossible to talk about appearance without also considering the color. While oil-based finishes can provide a yellow tint, they are still clear coats.
If you are looking for pizzazz, then wood dye, stains, and paints are the ones to beat. Colorful stains complement the glossy appearance of whatever finish you apply on top of it, while paint is a wonder on its own.
For those that are happy with the color of the wood, then water-based finishes will keep it as it is.
5. Toxicity
When applying wood finishes, it is important to take great care to prevent illnesses. This is because most household products, including non-natural finishes, emit high levels of VOCs. Some also contain known carcinogens, and a few of these are also highly flammable.
As such, not all of these are environmentally friendly or fit for use around children, pets, or people with respiratory conditions. Always check the label before application.
While these finishes are not toxic after they cure, the application process is the one you need to be wary of, especially lacquer.
6. Ease of Use
The next thing you need to consider is your skill level and what you can confidently apply without ruining the job. Varnish and lacquer are the hardest to apply correctly, while the oils are pretty simple.
There is no point attempting something complex like French polishing on day one when you don’t know how to paint without leaving streaks. After all, it is possible to achieve the high-gloss visage of French polish with a finish that already has a high gloss sheen.
7. Tools Required
As an extension of the previous point are the tools you need for the job. Depending on what you’re applying, you might need a brush (synthetic or natural bristle), roller, pad, lambswool applicator, rag, cloth, HVLP sprayer, or just your fingertips.
Other tools you may need are tack cloths, sandpaper, power tools, paint strippers, scrapers, and steel wool.
Again, if you are new to this, it’s best to keep it simple and stick with a finish that doesn’t require too many tools.
8. Drying Time
It is nearly impossible to state how important this is. When you have a large project planned, the drying time alone can take anywhere from a few days to a few weeks. Then add the curing time on top, and you’re going to be waiting for at least a month.
Drying times can be so frustrating that some people are happy to prioritize them over health, safety, or even appearance.
Water-based finishes may not look as pretty as oil-based finishes, but they dry in as little as 2 hours, while many oil finishes require at least 24 hours between coats.
Lacquer is the fastest drying of all the options. However, its other shortcomings – not as durable or waterproof, high toxicity, and complex application method make it one of the least desirable for novices.
To ensure a reasonable drying time, always ensure you apply any finish as the manufacturer recommends. Otherwise, you could end up waiting for much longer for the finish to dry.
Tips for Applying Wood Finish Properly
You can always tell when wood finish has been applied by an expert. The surface is smooth without brush marks, streaks, and puddles, and the wooden object looks like it just came out of the factory.
Besides the aesthetic beauty, wood finish can prolong the life of the project by protecting it from water, heat, UV light, scratches, scuffs, stains, mold and mildew, and so much more.
However, you won’t get any of these benefits if you don’t apply the wood finish properly. So here are a few things to do to ensure smooth and accurate application.
Remove Existing Finish
The first thing you need when applying wood finish is a smooth, even table. If there is an existing finish that has been there for months or years, chances are there is a lot of dirt in it and stains and scratches.
You would need to get rid of this layer before you can apply a fresh finish, and there are several ways to do that.
1. Sanding
The safest and arguably the best way to remove most wood finishes without a solvent is by sanding. Sanding serves the dual purpose of getting rid of an unwanted finish and making the wood smooth.
Sanding is great for removing paint, lacquer, acrylic, varnish, and shellac. If the coat is very thick, you can use a palm sander for small jobs and a random orbit sander for larger ones. For really small jobs or to work in between crevices, you would need regular sandpaper.
Before sanding, always wear a respirator. Sanding releases a lot of dust into the air and may also release harmful substances such as lead and chromium, which, when inhaled, can cause mild to severe health problems.
2. Chemical Strippers
Chemical strippers are very effective at removing every type of wood varnish, and they won’t damage the wood if applied properly. Chemical strippers and paint strippers make quick work of removing polyurethane, paint, and varnish.
However, this efficiency comes with a warning. Many strippers contain methylene chloride, which has been proven to increase chances of cancer, neurological and liver problems.
You need to take extreme care when working with chemical strippers – work in a well-ventilated space indoors, wear protective coverings for your eyes, nose, and hands, and keep all pets and children away from the work area.
3. Solvents
Whenever a wood finish has a solvent, it makes removing it a lot easier. Shellac and lacquer can be removed by denatured alcohol and lacquer thinner, respectively. While this method is much safer than using chemical strippers, you need to be extra careful, so you don’t damage the wood.
Prepare the Wooden Surface
Once the old finish is gone, assuming there was an old finish, it is time to prepare the wood. Wood furniture finishes may have different properties and application methods, but two things are quite common:
1. Sanding
As mentioned earlier, you can’t or rather shouldn’t apply finish to an uneven surface. To this end, you need to sand the wood until it is smooth.
Depending on the type of wood and what was previously on it, you may start with 120-grit sandpaper. First, test it out on an inconspicuous part of the surface. You can then adjust the grit lower or higher depending on what you see.
Always sand with the grain, not against it. Once you are done sanding, clean the surface thoroughly with a vacuum cleaner, tack cloth, or a lint-free rage dipped in water.
Leave it to dry, then move on to the next step.
2. Stain
Stain does a great job of accentuating the wood grain and emphasizing its natural beauty. It can also get the wood to a desirable color, usually darker than the original.
You can apply a stain with a cloth or a brush. Depending on the color you are using, you might only need one coat. Make sure you apply with the grain and wipe out any excess stain with a cloth.
Even though stain looks great, you may not need it for every application, especially if you are painting. If so, then skip this step and go straight to applying the finish.
3. Applying Wood Finish
It is important to re-emphasize at this point that no two finishes are the same. They have different application methods, storing methods and often use different tools.
It is also important to stress that the only way to get the best out of a wood finish is to apply it as directed by the manufacturer. Anything less will yield undesirable results, and you’ll find yourself with a refinishing project much quicker than you imagined.
We have written a number of articles detailing how to apply the different types of wood finish properly. These articles also go into detail about the pros and cons of each type of finish.
If you are ready to begin applying a new finish, we suggest you start there.
Always End with a Finish
When you have worked so hard to construct any piece of wooden furniture, it is imperative to nail the final step of choosing the right wood finish.
As discussed, this goes beyond choosing a penetrating finish or a surface finish. You have to look deeper into the qualities of the product you want to use.
Finally, always ensure you follow the proper application process, and you’ll be left with a gorgeous, flawless project you’ll be bragging about for years.
