While you might think your woodturning projects are done when you have finished shaping the bowl, plate, pen, or birdhouse you’ve been working on, there’s one more step to take: selecting and applying the right wood finishes for your project.
Not sure of what kind of finish might be best? Read below to learn more about the advantages of using a finish, the different types of finishes available, and which projects they might be best for.
Wood finish can be made of many things, which we will discuss in more detail below in Types of Finishes. In short, however, a wood finish is a type of liquid that is applied to the surface of a completed wood project. This liquid dries into a protective coat either by seeping into the wood itself or by forming a hard layer over the top of the wood.
There are many reasons to use a wood finish on wood turning projects. Wood finish can help make wood surfaces stronger and more resistant to water, and it also increases the appearance of the wood, giving completed products a low sheen or high shine, depending on the type of finish and project.
Using a wood finish isn’t just about aesthetics, though every wood turner wants their finished products to look stunning. Finished wood is also easier to maintain, as it sustains fewer scratches and doesn’t hold fingerprints, depending on the type of finish used. Some wood finishes can protect against UV rays and high humidity, as well, which is especially helpful if the item you are making will be used or stored outside.
Finishes also help seal up pores in the wood, making the wood cleaner and more sanitary, as bacteria are not able to penetrate the wood. This is important to consider if you are making items like bowls, plates, spoons, or any other kitchen implement that needs to be food safe and washable.
Unfinished wood has its own charm, but it is much more likely to get warped or cracked, or even begin rotting if penetrated by moisture. It is important for every wood turner to understand what kinds of finishes are available and which ones might be better for certain projects.
View the finishing process of the Pixie Fairy Bowl project, or check out our YouTube channel to watch the project in full.
Now that you have an idea of what wood finish is and why you should use one on every project you complete, the next step is to understand what kinds of wood finish work best for various kinds of projects; not all wood finishes are created equal.
Deciding which wood finish to use requires a wood turner to consider the appearance and size of each project and its intended use, as well as the durability and application of the finish, and the ease of cleaning or maintaining the finish.
Penetrating oils are some of the most common kinds of finishes. As the name suggests, these oils soak into the wood, penetrating and sealing as they go.
Penetrating oils, such as tung oil, linseed oil, Danish oil, and cedar oil, are easy to use and provide a low-sheen, satin-like appearance. Mineral oil also falls in this category. These kinds of oils are best to use if you want to preserve the natural beauty of a piece of wood.
Penetrating oils have many benefits; they are low maintenance and increase the water resistance of the wood. They are also food-safe, which means these types of finishes are especially good for finishing bowls, plates, spoons, or other kitchen implements. They can also be used on baby rattles or other toys that might find their way into small mouths.
Penetrating oils do take longer to dry, so if you are trying to get a project done quickly, this might not be the best choice. It is advisable to wait 24 hours between applications if you are applying a second coat.
Film Finishes are another popular type of wood finish. Unlike penetrating oils, which seep into the wood itself, these film finishes form a “film” or solid layer on top of the wood.
These types of finishes include shellac, polyurethane/varnish, lacquers, and water-based finishes.
Water-based finishes are one kind of film finish, and true to their name, they are water-based and contain no petro-chemical solvents. Instead, they are made of water mixed with acrylic and polyurethane resins.
Water-based finishes are easy to use and can be applied with a brush, sprayer, or even a paper towel. These types of finishes are also food-safe and can be cleaned up with water. Water-based finishes work well on medium to large projects like salad bowls or platters.
Water-based finishes are versatile in their appearance, as they can provide a low or high sheen depending on your desires for the piece in question. All the wood turner needs to do is apply more coats for a harder, more durable finish, and buff it to the desired shine.
It is worth noting that water-based finishes behave somewhat differently from other finishes, so if you are used to using lacquer, you will need to adjust your mindset before using the water-based finish. Water-based finishes raise the grain more than other film finishes, so it might be worth sanding the surface of your project a couple more times before applying this kind of finish.
It also helpful to know that water-based finishes behave differently from oils; while warm or humid weather causes oil finishes to maintain their viscosity, water-based finishes will tend to set faster in warm weather. Plan to apply water-based finishes in a cool, dry atmosphere if you want to have time to rework any spots that may need another coat.
Shellacs, varnishes, and lacquers are technically different things, but they are often lumped together in the finishing world because of their similar properties and because they are often used together.
Shellac is actually made from insect secretions, and in nature is used to protect larvae. In woodworking, shellac can be wiped, sprayed, or brushed on a piece to create a protective coating. Keep in mind that, while the original shellac is not toxic, the kind created for woodworking is toxic because it is mixed with chemicals to keep it shelf stable.
Shellac is not as durable or water-resistant as lacquer or polyurethane varnish, so it is often used as a first coat underneath lacquer or varnish. It is also helpful in preventing finish incompatibility, so that a woodturner could apply an oil-based finish, add shellac, and then apply a water-based finish.
Lacquer has become a catch-all term for many different substances, but most lacquers have comparable properties to shellac. They are made of nitrocellulose mixed with plasticizers and pigments. Lacquer is extremely durable and is resistant to heat and scratches. It forms a harder surface than shellac, making it ideal for polishing to a high shine, but is not UV-resistant, so it should not be applied to pieces that will be used outside or stored in direct sunlight.
Although lacquer is not ideal for wooden pieces that will be used outside, it should be applied outside or in a well-ventilated area, ideally with a high-volume low-pressure sprayer. Lacquer is ideal for decorative pieces but is less suitable for kitchen implements or other pieces that need to be food safe.
Polyurethane is another kind of wood finish that is technically a synthetic resin (see our previous post on Turning with Resin for more information on resins). Polyurethane is even more durable than lacquer and can be purchased in both water and oil-based forms.
As you might guess, the oil-based polyurethanes are stronger than the water-based ones, so consider what kind of project you are finishing; something that will be in direct sunlight or exposed to water would be better finished with an oil-based polyurethane. However, oil-based polyurethane takes longer to try than water-based polyurethane, so make sure to plan for time to let the finish set if you are using an oil-based polyurethane.
Waxes (like beeswax and carnauba wax) are common natural finishes for wood that give a high shine. However, these types of finishes are perhaps the least protective, and may need to be reapplied often, depending on how often the piece you are finishing will be used. Waxes are good to use for medium to large projects, and they should be used in conjunction with a sealer; otherwise, the project may get dull and streaky.
Friction polishes are an extremely popular option for woodturners because, true to their name, they require friction to be applied to a piece of wood. Burnishing (or rubbing a piece of wood forcefully with a cloth or steel wool) can be difficult and time consuming, but this process is much easier when the piece is already mounted on a lathe.
Friction polishes are made from a combination of wax and shellac and can be found in both liquid and bar form. Both liquid and bar forms can be applied straight to the wood as it sits on the lathe. A wood turner who is less familiar with the polish might start by adding the polish to the project as it sits stationary on the lathe, and then use a cloth to wipe the polish into the wood at a slow speed. Alternatively, a wood turner could turn the lathe on and apply the polish as it turns.
One thing to keep in mind about friction polishes is that they rely on heat from friction to cure, so it may streak if applied to larger projects, like bowls, because the heat is not as high in the center of the bowl. Friction polishes work especially well for spindle turning and for smaller projects, like pens.
One kind of liquid that may not spring immediately to mind as something to use as a wood finish is glue. The most popular kind of glue to use on wood turning projects is CA, or cyanoacrylate, which is super glue. CAs are applied while the wooden project is still on the lathe.
CAs are user-friendly and not likely to streak. The finish dries fairly quickly and is quite durable, forming a coat on top of the wood. This kind of finish is best for small projects like pens, rings, or wine stoppers. The finish will dry with a satin appearance, but it can be buffed to a higher sheen if desired.
However, CAs do require a specialized kit and a multi-step process, so you will want to make sure to follow the directions carefully if you are not familiar with this kind of finish. You will also want to wear gloves and a face shield while applying the CA to make sure that it does not stick to anything besides the wood. Proper ventilation is also key when using this kind of finish, so make sure that your work area has the ventilation necessary.
You now have a good idea of what a wood finish is, why you should use one, and what kinds of finishes are out there. However, there is one more thing to note before you begin applying finish to everything within your workshop: your projects will benefit from the use of a sealer before you apply a finish.
Sealers catch any loose fibers and set the grain so that your finish will go on smoothly. The only time you would not need to use a sealer is when using an oil-based finish. Sealers soak into the wood and set the grain. Light sanding should be done after the sealer has soaked in and before the finish is applied.
There are many types of sealers available; we discussed shellac above, which can work as a sealer, as can acrylic and cellulose. Alternatively, you can plan to apply more than one coat of finish and sand after the first coat to allow the second coat to cover smoothly. This essentially makes the first coat of finish into your sealer.
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