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When you're done with your woodworking project, of course you want to protect it. A top coat protects the finish of your project, as well as the wood itself. If you leave the wood (and any stain or paint you've used) as it is, it's likely to get scratched or dirty, and will also get damaged by watermarks if it comes into contact with moisture. By using a good wood finish, you'll keep your wood and its finish clean and protected, and prevent it from damage, wear and tear. You can apply a clear finish so as to accentuate the grain, or even give it a "wet look" if you like. In general, unfinished wood will develop a dull matte texture that will not show off the grain.

No matter the woodworking project you're working on, there are two basic finishes you can apply. The first is called an "evaporated finish." With this type of finish, it "cures" and becomes hard simply by drying. These types of finishes include lacquers and water-based finishes. You can soften these finishes with heat; therefore, they are given the name "thermoplastic."

The second type of wood finish is called a "reactive finish." This is cured by allowing it to react with another component, such as air, or with another chemical added just prior to the finish's application. Some examples of these include oils in oil-based varnishes or catalyzed lacquers. These types of finishes are called "thermosetting finishes." Unlike the thermoplastic finishes, these finishes are not softened with heat or with the original solvent used.

Within the reactive finishes are two different types of oil finishes. These are oils that dry when exposed to air or oils that do not dry when exposed to air. In example of an oil that does not dry when exposed to air is mineral oil, or baby oil. Those that do dry protect would better than those that don't dry. Therefore, usually, the ones that do dry should be used to finish your wood project.

Most often, linseed or tung oil is used to finish wood. These are distinguished from other types of wood products because they are "true" oils. Both penetrate the finish, which means that they enter the wood fibers themselves. Then they harden within the wood, which makes them the easiest to apply. Simply wipe down wood with them to allow them to penetrate the wood for a few minutes, and then wipe off the excess with a clean rag. If you apply several coats, you will not build up a hard film like you might with a varnish or lacquer, because the film itself dries to a very soft and smooth sheen.

Linseed oil is made from the flax plant. The oil itself is pressed from the plant. It is available both in on refined (also called "raw") form or in refined form. Unrefined linseed oil dries quite slowly and is usually not used on wood. By contrast, boiled linseed oil is thicker and dries more quickly. Usually, the boiled linseed oils available today also have chemical additives to speed up the drying time, which makes them much more suitable for finishing wood.