Fully understanding wood finish types requires either a degree in chemistry or decades of woodworker experience. But fortunately there are a few basic recipes that can be followed for all skills of woodworkers to achieve a glossy, unique color or even food-safe finish.
While traditional wood finishes required hours to dry and often impacted the color of the wood, newer finishes have evolved that dry quick and won’t yellow.
In this article learn about finishes for internal and external projects, how to prepare wood for finishing and top wood finishes.
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Wood Finish Types
From protecting wood floors for decades to delicately covering white furniture without yellow a wood finish must be versatile.
And durable.
And produce a sheen that is pleasing to the eye.
But what types of finishes are best for your project? Well, generally finishes are available as:
- Clear wood oils
- Wood stains that color the wood
- Food-safe tung oils
- Semi-transparent stains
- Epoxies that provide extreme hardness and waterproofing
- Plastic-based polyurethanes
- Water-based polycrylics and urethanes
- Spar varnishes for exterior wood
- Waterproofing finishes for decks
- And, well, you get the idea…
But the number one place to start understanding wood finishes is know the difference between a penetrating and surface finish.
Penetrating vs. Surface Wood Finishes
One of the first things to understand with wood finishes is they come in two distinct categories:
- Penetrating finishes work to, well, penetrate into the top layers of the wood fibers (and the fibers themselves). They may change the color of the wood, or simply act as a protectant.
- Surface finishes will form a protective layer on top of the wood, and can be used stand-alone for a clear wood finish or with a penetrating finish.
Types of Penetrating Wood Finishes
As you likely know a penetrating wood stain has a unique chemical composition. First, all penetrating stains use a volatile carrier that moves an iron oxide pigment deep into the surface of the wood.
Once in place, the volatile simply evaporates to leave the finished wood color. Then as the volatile evaporates a resin will adhere the pigment to the wood fibers.
Seems simple, right?
Well, as with most wood finishes, there are both water-based and chemical based volatiles that will dictate the toxicity of the stain. And, higher quality stains will use an iron oxide that will resist fading under UV exposure.
Water Based Penetrating Stains
As the name implies this type of wood stain uses a water mixture to carry the pigment and resin adhesive into the wood fibers. Featuring a less toxic finish both during application and (if the wood is penetrated) during use water based stains are gaining in popularity.
Key features:
- Low toxicity wood finish
- Simple application
- Reduced need for wood conditioners
- Available in a wide variety of colors
Concentrated Wood Dyes
When wood stains blotch and cause coloring headaches a professional woodworker will turn to a wood dye.
In fact, one of the woods many professionals will refuse to stain include hard maple, birch and even pine as the wood fibers will not evenly accept even a high quality stain.
Wood dyes work differently than traditional stain by:
- Mixing with water or alchol for a thin mixture
- Low viscosity allows for deeper penetration than thick pigments that may sit on the wood surface
- Even dye application will produce a more even appearance
- And, dyes can even be mixed with shellac or other (compatible) top coats to form an even more uniform tone to the wood.
Oil Based Wood Stain
Similar to water-based stains and dyes, an oil based stain penetrates the top layers of the wood to deposit a pigment.
And these stains have been used for centuries as the oil-based accelerant has been readily available and easy to work with. In fact, most oil based finishes simply wipe on and off with a rag with no need for brushing.
However, consider toxicity both in the application as well as the cleanup process. Because the accelerant evaporates a pigment will be left on, well, everything. Requiring another chemical such as mineral spirits to clean-up surfaces after staining is complete.
Wiping Stains
When it comes to woods that just don’t finish evenly with a deep penetrating stain woodworkers will turn to wiping stains for:
- Birch
- Maple
- Pine
- Popular
While almost a surface finish, wiping finishes work by depositing the pigment on the surface and require a quality sealing coat to lock the finish in place.
Tung Oil
There are few wood finishes as versatile as Tung oil.
First, for high quality (and properly labeled) Tung oil brands the wood finished with this oil is considered food safe. Since tung oil works to deeply penetrate the wood and, essentially, become part of the wood it doesn’t flake or leech into what contacts it.
All of which make this finish popular for cutting boards, sealing outdoor furniture that requires a non-oily residue or even as an oil application prior a surface wood finish.
Surface Wood Finishes
Used either with a penetrating finish or stand-alone as a “clear coat”, a surface wood finish aims to provide a protective surface over the wood below.
And, as woodworkers know, these types of finishes are available in a dizzying variety of chemical composition and application possibilities:
- Polycrylic
- Polyurethane (solvent, water, urethane)
- Shellac
- Epoxy
- Water-based topcoats
- Lacquer
- Liquid Wood
Polyurethane Surface Wood Finish
Of all wood finishes there isn’t a more well-known finish than polyurethane.
But, what most woodworkers don’t stop and ask is: just what is polyurethane? Well, polyurethane is basically a liquid plastic composite that is resilient, resists scratching and form air or even liquid tight seals.
Lastly, polyurethanes are available in both water and solvent based. When given an option, more DIY’ers and woodworkers will choose the water-based finished for both reduced toxicity and green impacts.
Polyurethane vs. Urethane
There are many wood finishes marketed as simply “urethane”. So are they different than polyurethane? According to Performance Painting they are one and the same thing. “Poly” simply means many urethanes.
Liquid Wood: Paint On, Then Stain to Color
Even professional woodworkers may not know about this unique wood finish. While technically a mix of paint that is then stained to form a “new” wood finish, liquid wood can be applied to the surface of just about anything.
Here’s how it works:
- Wood fibers are processed into a paintable product
- Surfaces are painted, then allowed to dry
- Wood stains are then used to apply a finished look
- Then, lastly, a surface wood finish is applied to seal the wood
This unique finish by Retique It is perfect for restoration of old wood pieces that have been damaged past recovery.
Oil Based Wipe on Urethane
While a traditional polyurethane is wiped on, a better solution for many jobs is a wipe on urethane that applies quickly and adds a rich tone to wood.
With a quick dry formula many urethanes will dry in under an hour and can be sanded between coats using a simple sanding sponge.
Epoxy Wood Finish
For wood tables and bars the place woodworkers start and finish with is a wood finish type that offers arguably the best protection: epoxy.
Epoxy is a two part finish that combines an epoxy and hardener that forms a thick, high gloss finish that protects bars around the world. And while epoxy is durable, it is also:
- Food safe once cured
- Self-leveling (most formulas)
- High gloss
- Works on a variety of surfaces beyond wood
Clear Dry Polycrylic
A clear wood finish on many woods can be hard to find.
With many finishes yellowing over time a lot of DIY’ers and woodworkers look for a finish that will stay clear over the years. And why most find a water-based polycrylic best for:
- Can be applied over stains or paint
- Will not discolor even pure whites
- Designed for furniture and cabinets
Top Finishes for Outdoor Decks
Choosing a wood finish for decks isn’t always simple.
While many desire the natural wood look on new decks, for older decks a decision is often required of hiding old wood blemishes vs. retaining a wood look.
Regardless of the deck finish or stain, the first step in any deck stain project is to properly prepare the wood for finish first.
Preparing a Wood Deck For Stain
Most homeowners and professionals will typically choose to pressure wash a deck as the force of 1500-psi will quickly remove both old stain and mold.
But there are some others that will choose to sand a deck.
Which method of cleaning a deck for stain is best? Well, consider what happens AFTER the cleanup is done:
- Pressure washers can tear wood fibers out, and if improperly used leave light and dark streaks where the pressure washer nozzle started and left the wood.
- Meanwhile, sanders can leave sharp edges and, for random orbital sanders, even sanding swirls that will show in the finished stain
The best option for most applications? Use a pressure washer and go with the grain.
Natural Oil Deck Stain
After investing thousands (and thousands more) into a cedar, redwood or other decking many deck owners need to decide how to best protect the wood.
And while the simple answer is with some hard work and commitment to a few coats of oil over the years, the trick is choosing the right deck stain.
So, similar to penetrating interior wood stains, one of the best outdoor wood finishes is a penetrating oil that builds up to provide protection both within the wood and on top.
Recommended: Cabot Australian Timber Oil is a three part Tung, alkyd and linseed oil with a reputation for durability.
Semi-Transparent Waterproofing Stain
Using the protective qualities of an acrylic, a high quality semi-transparent stain will provide a wood tone to both new and old decks.
But, as a surface stain, provide a way to seal the wood from water penetration. Key features of this type of deck stain include:
- Improved moisture vs. a penetrating (only) finish
- Better UV protection
- Most are mildew-resistant
Some products, such as Kilz, offer a three year warranty for horizontal surfaces and up to a five year for vertical.
Marine Grade Water Sealing Wood Finish
While every deck, dock or other outdoor wood finish types requires some research into the manufacturer claims (buyer beware), one of the newer wood finishes is the Seal Once marine wood sealer.
With a design that seals wood cells, but doesn’t trap water by sealing the wood pores, this product allows for wood to “breathe”.
Polyurethane vs. Epoxy Wood Finishes
One of the most common questions on wood finish types is the difference between polyurethane and epoxy.
Or, for that matter, polyurethane and just about any other type of wood finish.
When it comes to epoxy, to start, epoxy is a two-part solution that is combined, poured and then allowed to cure to an incredibly hard finish. It isn’t applied in coats, can be lightly sanded and creates a durable, water-proof finish great for bar tops.
Polyurethane, on the other hand, is a plastic-based finish that forms a protectant over wood using multiple coats of finish. While polyurethane forms a hard finish, it isn’t as durable as epoxsy.
The verdict? Use epoxy for thick applications such as filling gaps between live edge wood slabs. And use polyurethane for regular duty cabinets and furniture that will not receive constant water contact.
Wood FInishes That SPray On
Professional painters and woodworking shops all use a high volume spray system that quickly coats the wood with an even finish.
But is this a type of finish for entry level or small shop woodworkers? Well, the answer depends on how you’ll intend to use this finish:
- Spray finishes can create a high volume of (toxic) overspray that must be properly collected and ducted
- Projects like passage doors and cabinets with curvy surfaces are great candidates for spray
- Intricate projects with small pieces
- Large, flat surfaces that can’t show brush marks
Just remember that spray finishes can create a high volume of (toxic) overspray that must be properly collected and ducted.
Popular spray finishes range from a standard spray can to professional HVLP spray systems. And, most use a lacquer that is properly thinned, heated and paired with a sealer for a perfect finish.
Frequently Asked Questions
Which finish is best for wood?
The best finish for wood depends on the projects use, location (interior vs. exterior), gloss of the finish and if it will be used in a food-contact setting. Since wood finish types all vary by these uses, there is no single best finish. Rather, there are the right types of finish for the woods intended use.
Is it better to wax or varnish wood?
While wax will provide a thin coating on wood, varnish is better because it provides both a smooth finish but also protects and adds a rich color to the wood.
What wood finish is best for a bar top?
Epoxy is widely accepted as the best wood for a bar, table or any other high use surface that will be susceptible to dings. Because epoxy is a two part mix, with one part a hardening agent, this finish will dry to a hardness that prevents common glass dings. And, as it is extremely durable, will resist dings and chips that other types of wood finish cannot.
- About the Author
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Eric has been a professional woodworker for over thirty years and has worked in small cabinet shops making everything from kitchen cabinets to hand-made furniture. Now working from a home woodworking shop Eric is sharing his passion for woodworking, tool advice and how-to knowledge from his Minnesota-based woodshop.
