There are many brushes used in a finishing shop — too many to discuss in a short article. But I’d like to give you some things to think about when making a selection. Consider this a brief overview, from my perspective.
The most important part of the brush is the stock, or the collection of bristles, hair or filament, natural or synthetic, that hold and dispense the coating material. Common natural bristles are made from hog hair, largely from China and Russia, which can vary in softness and stiffness. The ends of the bristle are naturally tapered and flagged (split) at the small ends to hold more coating and distribute it evenly.
Horse hair is used mostly for cleaning brushes. Extremely soft hairs from sable (the finest is called Kolinsky) and red sable — any red hair from the weasel family — are found in many good art brushes because the finely pointed hair has great spring, strength and absorbency. Squirrel also has high absorbency and finely pointed hairs, but doesn’t have the spring of red sable.
Ox hair is relatively inexpensive, strong, silky and probably the most durable of the soft hairs, but will not point as precisely as sable. Fitch is from skunk or European polecat. You’ll see this in flowing brushes for varnish and shellac. “Camel hair” may be from one or more animals, such as ox, goat, squirrel, or pony, but oddly, not camel. Badger hair (yes, really from a badger) makes for a very soft yet springy bristle. It makes a great flowing brush with a thick, tightly packed stock or a wonderful glaze blending brush when set in three rows.
Synthetic fibers such as nylon, polyester or polypropylene come in a variety of styles, cost and quality. I prefer synthetics for water-based paints and topcoats because they’re easier to clean.
The ferrule and setting
The stock is fixed in a rubber, plastic or resin setting that is shaped flat, round, oval or semi-oval and usually wrapped with a metal ferrule. The handle is attached at the opposite end from the stock. The setting and ferrule help determine the shape of the stock in cross section and profile. Descriptive terms for the shape of the stock include flat, chisel, fan, round, dome top, angular, sash, oval, semi-oval and cup chisel.
The setting should be able to withstand the solvents with which it will be used. Some solvents can soften some settings, loosening the hair. The ferrule should never be immersed in the coating or solvent because it is difficult to clean out, resulting in rust or the swelling of a wooden handle.
Handles can be long or short, round or flat, unfinished or lacquered, stubby, straight or curved. The handle should be comfortable to use and proportionate to its stock. For example, an artist might choose a long-handled brush to stand away from an easel, while a touch-up technician doing detailed in-painting over a repaired area might choose a short handle to have his face very close to the brush tip.
Measurements are given in terms of width, diameter of the stock, length clear (the length of the fiber, hair or bristle that is clear of the ferrule), and the thickness of the stock at the ferrule (“X”, “XX” or “XXX” thick). The shape and thickness of the stock influence how much material the brush can hold. For applying a traditional oil varnish over a large area, you want a brush that will hold a lot of varnish so you can complete a stroke without having to reload the brush. For a small touch-up, where you will only be loading the tip of the brush, a thinner, narrower and more easily controllable brush will be better.
For clear finishes
Clear finishes applied by brush are generally pretty slow drying and are flowed on with a well-loaded brush. Properly prepared and applied, they should level without running or puddling, and without a lot of brushing. Faster-drying lacquers and shellac need to be applied quickly without dragging the brush. Badger and sable flat stock and chisel tip (X or XX thick) brushes will work well for these thinner coatings.
For the traditional oil varnish or high-viscosity polyurethane, I prefer a badger or fitch (XX or XXX thickness) flowing brush with a round handle. The round handle feels good against the web of my hand and I’m controlling the brush by the ferrule. The pressure you apply against the ferrule, curving the bristles, determines the flow rate of the material. The quality and maintenance of the brush strongly influences the quality of the coating application.
For stains and glazes
While you don’t want to be careless in applying stains and glazes, the brush becomes less important. I will almost always apply a dye stain by spray or wiping with a cloth. I might need a small brush to get the dye into inside corners or carvings. Application of a pigment wiping stain can be done with any brush that will hold sufficient material to efficiently wet out the surface quickly, without dripping and without having to be loaded frequently.
Make sure that the stock and setting will tolerate the solvents, and try to use staining brushes only for that purpose as it could be very difficult to remove all of the color. These suggestions apply to glazing stains also, though they may be more viscous and less likely to flood or drip from the brush. You may want a little more spring in the stock for pushing the glaze into detail such as carving or physical distress (such as worm holes, rasp wearing, scratches and open joints). I like a round, thickly packed black bristle for this, but an inexpensive synthetic can work as well.
Once the glaze has been applied, dried and roughly wiped, I like a badger hair blender (sometimes called a softener) to do the softening or blending. This is a step often neglected by novice finishers, resulting in a less subtle and pleasing effect. It is essential in good faux finishing and almost all common glaze effects to avoid being too obvious. The badger blender should be wide and thin, as it does not have to hold material, but you’ll need to move it around. The hairs have good spring, but a naturally tapered tip almost as fine as mink. These are expensive, but worth it if you take care of them.
Touch-up brushes are usually smaller artist-type brushes that are used to replace lost color on an item, replace or fake grain to tie in a veneer patch, or to color, grain and topcoat a fill. Various sizes of red sable, camel, ox hair or Taklon (brand name for synthetic fibers) brushes are most often used. For very fine graining, I like a Taklon springy polyester fiber that tapers to a needle fine point with a 5-1/2” handle for use with solvent- or water-based coatings, including acrylics.
For very fine area graining, a fan shaped red sable or Taklon brush, loaded very lightly, can be a real time saver. For long lines, a dagger (or sword) lining brush is good. You can control the thickness of the line by varying the pressure on the brush. A rake-style of brush with hair cut into distinct teeth or fingers can also be used also to fake in the grain. A mop-style brush with a rounded dome-top stock can be used to blend or soften, or to apply a translucent wash.
This article could go on forever describing every brush available. I’ll close with the recommendation that it’s worth the expense to buy high-quality brushes. They work better, last longer and are easier to use than the economy versions.
Greg Williams, formerly senior touch-up and finishing instructor for Mohawk Finishing Products, is now a freelance instructor and consultant for finishing and touch-up. He can be reached at firstname.lastname@example.org.
This article originally appeared in the October 2011 issue.