How you apply a wood finish can be as important as the finish itself. Although there are many other popular methods of applying finishes - rags, non-abrasive pads, etc. - many people prefer using a brush. When using a brush, the goal is avoiding brush marks, wasting too much finish, and getting a nice long stroke that doesn’t require you to dip the brush into the finish endlessly. The cost of the brush is usually a consideration as well.
Quick-drying finishes such as shellac or lacquer require extremely fine-haired natural animal hair brushes that will give you a long stroke without brush marks. If the brush is well-made and the hair is dense enough, you'll also get a very long stroke with very evenly controlled release of the finish.
Polyurethanes and other varnishes don't dry as fast and are therefore self-leveling. (In this context I am using the word “varnish” to mean finishes that form a layer on top of the wood.) With a self-leveling finish if there are few brush marks after you put down the stroke finish, by the time finish dries the brush marks will be gone.
Oils and oil-based varnishes are really designed to soak into the wood, so what you really want to do is apply ample finish and remove the excess. Brushes are better for the application of the oil than its removal. Rags and abrasive pads are much better for this step; you’ll get some burnishing effect when you apply some elbow grease in the removal of an oil finish. (Oil-soaked rags must be disposed of safely - more on this topic below.)
Waterborne finishes demand a specific kind of brush. A natural follicle of hair has a hole in its middle, so using natural ox hair or china bristle for a waterborne finish poses a problem: in many cases the hair will absorb water and go limp. A far better alternative would be an artificial hair brush.
At the very top of our range of brushes is our 100% ox hair brush. This is a natural brush with lots of very, very fine hair ideal for quick drying, non-water-soluble finishes. It can give you a very long stroke with controlled-release of material and no brush marks. The fine hair also allows the brush to conform exactly to uneven or complicated surfaces (i.e., moulding, curves etc..). Unlike some other "shellac" or "beaver " brushes on the market, our brush is made of 100% European ox hair, a very fine hair, not china bristle. China bristle is a hog bristle that is been split at the very ends to give it a finer performance. China bristle works, but you won't get the long control stroke and you will get more brushmarks.
Ox brushes do not perform well with waterborne finishes, even quick drying ones. As previously noted, waterborne finishes make the brushes’ hair go limp. The solution is artificial hair. We offer brushes that use synthetic beaver hair - also very fine and also used in abundance in the brush for a luxurious feel.
Both of these brushes are expensive, possibly some of the most expensive finishing brushes on the market today. But they will reward you with great performance and long life. Ox hair brushes should not be used with polymerizing finishes simply because you can't clean them hundred percent and the brush will quickly get ruined especially with all that fine hair. Care of the finishing brush for shellac and lacquer is simpler: you don’t even need to clean the brush after use. The leftover finish will be redissolved in solvent next time you use the brush. With artificial hair after applying a waterborne finish, thoroughly wash the brush with soap and water and let it air dry.
For regular varnishes and other polymerizing finishes, we recommend either our round body China bristle brushes with either a flat or chisel tip. These brushes are a fraction of the cost of our superfine finishing brushes, and for self-leveling finishes just nice brushes to use.
China bristle brushes also work well for applying paints and other types of pigments.
Of course, not everyone prefers a brush. Another alternative for shellac is rubbing it on. This is the way a classic French polish is applied, using a pad charged with shellac. A classic rubbed- on French polish is the finest finish I have ever seen, no exceptions. Often people French polish all the flat parts and use the ox brushes for all the moldings and things you can't rub back-and-forth.
There is a real temptation when you're finishing to use a disposable foam brush. As long as the finish is self-leveling and doesn't dry instantly, you should be fine using one. But don’t skip on a foam brush either. Cheaper ones have a tendency to disintegrate in use - so have spares.
Applying oil finish is also very commonly done with a rag. In my view, rags aren’t as fast or as effective as the White BearTex pads, but it does work. But be sure to mind the following safety tip if you use rags. After you are done, gather the oil-soaked rags. The rags will give off heat and can burst into flames,. I personally know of three cases of shops and homes burning down because they a pile of forgotten rags smoldered and caught on fire. So either hang out each rag as if on an empty clothesline so each one can easily dry without its heat accumulating. Another option is to put your rags in a bucket of water.
The TFWW ox hair brush and synthetic brush are the best I've ever used.
Thanks, Joel, for the helpful information and great products!