There are so many helpful options when it comes to wood finishes for your project. Each finish has a specific purpose and function that separates it from the others. I’ve researched through the internet and put together a summary on the different types of wood finishes.
How do I choose a wood finish? You can choose a wood finish by determining if you need a Non-Toxic wood finish, what kind of protection your project needs, what kind of enhancement your project needs, and what kind of equipment you have available to apply the wood finish.
Keep reading below to learn more about wood finishes.
How Do I Choose A Wood Finish?
Like most woodworkers you probably use a few favorite finishes that produce consistently good results for you. When it comes time to choose a finish for a project, you naturally gravitate toward what has worked well for you in the past. After all why mess with success?
Or you learn about a finish that you’d like to try: it’s easy to apply, stands up to hard use, imitates an antique patina, or offers other qualities that capture your interest. Whatever the reason, you resolve to use it whenever the next opportunity arises. In some cases, you may build a project just so you can try the finish.
But what about those occasions when you know the results you want from a finish; water resistance, durability, luster, tint and so on, but don’t know how to achieve them? When this is the case, you must do a little research. First, define the results you want. How the finish should enhance the wood and what sort of protection it should afford. Review the available finishing materials and choose those that will create the desired effects. Finally, test these materials to determine if they will indeed produce the results you expect.
Finishing research needn’t be a time-consuming complex venture. In most cases, it’s a simple matter of regrouping the finishes in your mind to identify those that will produce the desired effect. For example:
- If the depth of a finish (or lack of it) is important, group the choices into penetrating finishes that soak into the wood and building finishes that form a film on top of it.
- If the project will be exposed to water, decide whether this exposure will be constant or occasional. Group the finishes into water sensitive, water resistant, and waterproof.
- To preserve or enhance the natural color of the wood, determine which finishes are clear and which have a natural amber or artificial tint.
To group the finishes for specific results, study the labels on the containers and read additional information provided by the manufacturer.
Wood Finish Enhancing Properties
|Penetrating||Drying Oils, rubbing oils, dyes, stains|
|Building||Shellacs, varnishes, polyurethanes, lacquers, waterborne resins, epoxies, oil and latex paints.|
|Flat||Most penetrating finishes after just one coat. Other finishes can be made to appear fly by adding flatteners or by rubbing them out with the proper abrasives.|
|Satin||Most penetrating finishes after several coats. Other finishes can take on a satin appearance by adding flatteners or rubbing them out with the property abrasives.|
|Glossy||Shellacs, varnishes, polyurethanes, lacquers, waterborne resins, epoxies, oil and latex paints, provided there are no flatteners added. For high closs, most finishes must be polished after curing.|
|Artificially Tinted||Stains, dyes oil and latex paints. Some varnishes, rubbing oils, and waxes are also tinted.|
|Natural Amber Tint||Rubbing oils, drying oils, shellacs, varnishes, polyurethanes, lacquers, epoxies, waxes.|
|Clear||(no discernible tint) Waterborne resins; a very few lacquers, varnishes, and epoxies|
|Transparent||Rubbing oils, drying oils, shellacs, varnishes, polyurethanes, lacquers, waterborne resins, epoxies, dyes.|
|Semi-transparent||Stains, thinned paints, transparent finishes with added flatteners or pigments, waxes.|
|Opaque||Oil and Latex paints.|
Wood Finish Protecting Properties
|Hard||Epoxies, polyurethanes, varnishes.|
|Moderately Hard||Lacquers, waterborne resins, oil and latex paints.|
|Moderately Elastic||Rubbing oils, shellacs (although shellacs become less elastic with time)|
|Elastic||Drying oils, stains, dyes, waxes.|
|Semi-permeable||Other waxes, shellacs, varnishes, polyurethanes, epoxies, oil paints.|
|Permeable||Drying oils, rubbing oils, lacquers, waterborne resins, latex paints, stains, dyes.|
|High Heat Resistance||Polyurethanes, epoxies, oil paints.|
|Moderate Heat Resistance||Rubbing oils, lacquers, varnishes, waterborne resins, latex paints.|
|Low Heat Resistance||Drying oils, shellacs.|
|Water-sensitive||Drying oils, some rubbing oils, shellacs, lacquers.|
|Water-resistant||Some rubbing oils, waterborne resins, interior varnishes, polyurethanes, latex and oil paints.|
|Waterproof||Exterior varnishes, polyurethanes, waterborne resins, latex and oil paints, epoxies.|
|Chemically sensitive||Drying oils, shellacs, waxes.|
|Chemically resistant||Rubbing oils, lacquers, waterborne resins, latex paints.|
|Highly chemically resistant||Varnishes, polyurethanes, epoxies, oil paints.|
|Highly durable||Varnishes, polyurethanes, epoxies oil paints, dyes.|
|Moderately durable||Shellac, lacquers, waterborne resins, latex paints, stains.|
|Not very durable||Drying oils, rubbing oils, waxes.|
|Highly Toxic||Epoxies, as well as some varnishes, paints, and rubbing oils.|
|Moderately Toxic||Lacquers, some varnishes, polyurethanes, some oil and latex paints, some stains, dyes.|
|Moderately Safe||Some drying oils, some rubbing oils, shellacs, some waterborne resins, some stains, some waxes.|
|Nontoxic||Some drying and rubbing oils, some waterborne resins, some paints, some waxes.|
Methods Of Application
|Wipe-On||Drying oils, rubbing oils, stains, dyes, waxes.|
|Brush-On||Shellacs, some lacquers, varnishes, polyurethanes, some waterborne resins, oil and latex paints.|
|Spray-On||Some lacquers, some waterborne resins.|
Do You Need A Nontoxic Food Safe Wood Finish?
It’s best to ask yourself this question first, for two reasons. Because there are so few nontoxic finishes, you can quickly narrow your choices if that’s what you need. And more importantly, when making eating utensils, food safe products, toys, or children’s furniture, your overriding concern should be the safety of the folks who will use these objects.
In addition to being toxic when you apply them, finishes may remain toxic after they’ve dried. Although the organic solvents evaporate, the resins and other nonvolatile substances remain. Most of these are not harmful by themselves, but some are. Heavy metal salts, for example (Driers) can be poisonous.
Usually, this residual toxicity poses no threat. But if these chemicals are ingested, they can be dangerous. When chewed or abraded by knives and forks, the finish can flake off and be swallowed. Or the mild acids in saliva and food juices may leach the finish out of the wood. To be safe, use finishes that retain little or no toxicity after curing.
- The traditional nontoxic finish is mineral oil. Unfortunately, mineral oil does not dry and you must periodically reapply it to the wood for continued protection.
- You can also use walnut oil, which does dry but does not form a hard film. Walnut oil is available at most health food stores, and several commercials finishes are made of nut oils.
- Shellac, in solid form, is nontoxic. But most commercially mixed shellacs contain driers or methanol. In order to make a nontoxic shellac, cut pure shellac flakes with hydrous ethyl alcohol.
- Manufacturers of Danish oil claim that it’s nontoxic when fully cured. However, it takes 30 days to cure completely. This is not the finish to throw on the kids’ toys the night before Christmas.
- Salad Bowl finishes are manufactured from FDA-approved chemicals and foodstuffs. They’re durable, but like nut oils, they do not form hard films.
- Several brands of waterborne resins are marketed as nontoxic. Because they flake off, they’re not recommended for eating utensils. But they are safe for children’s furniture and playthings.
- Finally, Milk Paint is relatively benign. It’s not recommended for eating utensils or objects that will be used by infants, but it’s safe for playthings and furniture that will be used by older children, age three and up.
Which Is More Important, Enhancement Or Protection For Your Wood Finish?
A finish has two purposes to protect the wood and enhance it’s beauty. Depending on the project and how it will be used, one of three will take precedence over the other.
For example, when finishing a project that will be used outdoors, you must protect it from the elements above all else. Once you have identified several weatherproof finishes, then you can worry about which of them will look best. If you make a fine piece of furniture that requires a deep, glossy finish, then appearance is paramount; protection is secondary.
Decide how you want your project to appear after it’s finished. Also consider how it will be used and in what environment. Furthermore, remember that every finish has certain properties that define how it enhances and protects the wood. Depending on the project, one or two properties may take a precedence over all the others.
What Enhancing Properties Do You Need In Your Wood Finish?
There are several ways that a finish can enhance the beauty of the wood. It does so by altering the appearance of the surface. Decide which of these is the most desirable:
- Penetration: The depth to which a finish penetrates will affect both the look and the texture of the wood. If it penetrates deeply, it may form only a thin film on the surface, and the natural texture of the wood will be preserved. If allowed to build on the surface, it will replace the natural texture with a smoother one.
- Depth: A transparent film builds on the wood to create depth. The visible distance from the surface of the finish to the surface of the wood. The thicker the film, the deeper the finish looks.
- Luster: A film can either reflect light, bouncing it back at you, or scatter it every which way. A highly reflective film is said to be glossy. If the surface scatters the light, it looks dull and flat. If it’s somewhere in between (both reflective and scattering), it has a satin look. You can control the luster by using finishes with added flatteners (usually powdered quartz) or by rubbing the hardened finish with various abrasives.
- Tint: All but a few finishing materials alter the natural color of the wood by tinting the surface. Varnishes, shellacs, and many other transparent finishes have a slightly amber tint which subtly warms up the natural wood tones. Stains, dyes, bleaches and paint can change the color dramatically. Only waterborne resins and a few other special finishes have no tint. These are said to be water clear.
- Opacity: The cloudier the finish looks, the more opaque it is said to be. Opacity depends not only on the resins and oils, but also on the colored pigments, flatteners, and other solids in the film.
What Protecting Properties Do You Need In Your Wood Finish?
There are also different ways in which a finish can protect the wood. Depending on how the project will be used and under what conditions, some of these will be more important than others:
- Hardness: In comparison to other materials, resinous films are not hard and depend on the wood for most of their strength. However, certain finishes resist wear and tear better than others, and are said to be “harder.” Harder finishes are sometimes brittle and prone to chipping.
- Elasticity: Films must be flexible and elastic enough to expand and contract as the wood moves. Generally, softer films are more elastic.
- Permeability: A finish should provide a moisture barrier so the wood won’t expand or contract too quickly when the humidity changes quick movements can ruin a project. The lower the permeability, the slower the moisture will pass through the film, and the more stable the wood will be. You can decrease the permeability of most finishes by applying additional coats.
- Heat Resistance: Projects may be subjected to high temperatures by spilled hot drinks, steam and hot pans and serving dishes. The temperature at which a film begins to soften and delaminate determines its heat resistance.
- Water Resistance: Some water-sensitive finishes allow the wood to soak up water, others exclude water but become cloudy when they contact it. Water-resistant finishes will keep their good looks and keep water out of the wood, but they won’t stand up to constant exposure. Only finishes that are rated as exterior are truly waterproof.
- Chemical Resistance: Finishes vary in their resistance to mildly caustic chemicals in household cleaners, mild acids in fruit and vegetable juices, oils from hands and foods, and alcohol in beer and wine.
- Durability: This is not an individual property, but rather a summing up of all the protective properties. If a finish is hard enough to resist abuse yet elastic enough to move with the wood, and resistant to heat, water, and household chemicals, then it’s very durable.
How Much Time And What Equipment Are Needed to Apply A Wood Finish?
It’s not enough to know that a certain finish can be made to produce a certain effect. You must know how to achieve that effect, and whether you have the time and the equipment to do it.
For example, both shellac and lacquer will build to a deep finish, provided you apply several coats. Shellac is usually brushed on and must dry for an hour or more between coats. Furthermore, it requires a light sanding between coats and thorough rubbing after the last coat keep the film even and to polish it to the desired luster. Lacquer, on the other hand, is usually sprayed on, requires less time between coats, and needs little rub-out. Consequently, you can build depth with lacquer much more quickly than you can with shellac. But lacquer also requires a spray gun, a respirator, and a ventilated spray booth.
In short, shellac takes more time, while lacquer involves more equipment. If you require a deep finish and time is not a problem, choose shellac. But if time is short and you can afford the necessary equipment, select lacquer. To help decide whether you have the time or equipment to apply a particular finish, consider its normal method of application. Don’t attempt a finish that stretches your resources.
What Kind of Finish Should You Use?
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