Types of brushes

Basically, there are three kinds of filaments used in brushes: natural – made from hog bristle or from ox or badger hair; synthetic – made from polyester or nylon; and natural/syn­thetic blends. The general consensus is to choose natural brushes for shellac and varnish, and synthetic for waterborne finishes. However, I’ve had good success using natural/synthetic brushes and synthetic brushes with shellac and varnish when I thin the finish by 10 to 20 percent with its solvent. The material used for the brush handle (wood or plastic) is less important than how it feels in your hand. For more controlled brushing, a handle length of 5″ to 6″ works well.

Natural brushes

Natural brushes work well on shellac and varnish because they carry more finish than synthetic brushes, so you can lay on more finish with each brush stroke, and maintain a wet edge as you work. When buying a natural brush, look for filaments that have flagged ends – a split at the end of each individual filament. The flagged ends enable the brush to hold more finish and release it with minimal brush marks.

There are two general types of natural brushes. The most com­mon are made from the hair of hogs, typically referred to as “bristle” or “China bristle”. If a brush is labelled “bristle” then it’s made of hog hair. Hog hairs have naturally split ends. They also taper from the base to the tip, which makes the hair strong yet gives it a lot of spring, so that it maintains its shape in use.

Higher-quality natural brushes are made from ox or badger hair, which is a softer, finer, and more pliable filament than ox bristle. You pay a premium for ox or badger brushes, but they can leave a finish that is as good as it gets.

With any natural brush you’ll want to remove any dust or loose filaments before you first use the brush. Shake it out vigorously, then dip it about half of its length into the appropriate solvent for the finish you’ll be using, and then gently tap it against the side of the container.

Synthetic brushes

For waterborne finishes use synthetic brushes, because the water in the finish will cause natural filaments to swell and lose their stiff­ness. Most synthetic brushes have polyester or nylon filaments, or some combination of the two. Neither is as absorbent as natural filaments, which means you have to load up the brush more fre­quently. Most manufacturers whip the filaments to split the ends into flagged ends to give a smoother finish. Chinex is a brand name for a synthetic brush with flagged tips, while Taklon is another brand name for brushes with very fine filaments, meant to mimic badger hair.

Brush widths

For large surfaces use a 2″ to 4″-wide brush, while for smaller panels, frames, edge work and legs, choose a narrower 1″ to 1-1/2″ brush. It’s true that an angled (or “sash”) brush allows finer con­trol in corners and tight spaces, but rather than adding yet another brush to my kit I simply switch to a narrower brush, which I find works just as well.

If you typically work with small items, then pick up a couple of small artist brushes (available with both natural and synthetic fila­ments). They excel at working in tight spaces, and the super-fine filaments allow the finish to flow onto the work easily with virtu­ally no visible marks.

Vary the load

When applying a finish, think about scale. A large surface can absorb finish at a faster rate than a smaller surface or narrow trim work. Using a heavier load on the larger surface makes it easier to maintain a wet edge. Conversely, applying too much finish to a carved or contoured piece will result in runs and sags that can be difficult to correct. With practice, and paying attention to the feel of the brush as you apply the finish, you’ll learn to identify the cor­rect load for each situation.

When loading the brush, you only need to dip the bottom third or half of the brush into the finish, and then wait for the finish to wick into the brush. Before moving the brush to the project, adjust the amount of the load by lightly pressing the brush against the side of the container.

Smooth strokes

Rather than brushing from one end of a panel to the other end, begin by placing the brush a couple of inches from the end of the panel and move the brush to one end in a continuous smooth stroke. After completing that stroke, return to the starting point and brush back to the opposite end. As you get to either end of the panel the brush should just glide off the top without moving down the edge of the panel. After completing the first pass, go back and use the tip of the brush to gently work the finish across the edge.

Keep brushes clean

Brush cleaning doesn’t have to be ardu­ous or time consuming. If you’re applying a finish over a day or two, then don’t bother cleaning the brush. Instead, suspend it in a container of the solvent for the fin­ish – just make sure the tip doesn’t stand on the base of the container or it will curl up. Before using it again, lightly press the excess solvent out of the brush on the side of the container.

To clean a brush used for varnish or water-based, you want to rinse the brush several times in the solvent for the finish you’re using (mineral spirits for varnish, water for water-based). I do this three or four times and then wash the brush several times with warm water and dish soap. For a varnish brush, rinse the brush first with a citrus-based cleaner and then again with water to remove the final traces of solvent from the brush.

Shake out any excess moisture by swing­ing it up and down several times, and then wrap the filaments with a piece of paper – you can use strips from paper grocery bags. This allows the bristles to dry and keeps dust from getting into the filaments.

My brush kit

My particular brush kit consists of two brushes for each type of finish. For shellac I use a 2″-wide ox-hair and a 3/4″ syn­thetic; for varnish, a 2″ and a 1″ bristle brush; and for waterborne finishes a 2″ and a 3/4″ synthetic. The type of woodworking you do will obviously affect your choice of brush.

Buy good brushes, practice applying the finishes you intend to use, take the time to clean the brushes after use, and you’re three quarters of the way to a perfect finish. The last quarter comes from experience.