Brushes are sized by width. As a rule of thumb, bristles should be about 50% longer than the brushes' width (and even longer on very narrow brushes).
Brushes with natural bristles should not be used with water-based paints. Before being used for the first time, natural bristle brushes should be soaked in linseed oil (not resting on their ends) for a couple of days in order to swell the bristles inside the ferrule, which helps to prevent their pulling out. Synthetic bristles, good for latex paints, can be destroyed by certain lacquers and other paints containing strong solvents.
There are four main classes of brushes:
Made in widths from 3″ to 6″, in ½ inch steps from ½ to 3 inches, and from 3 inches to 5 inches in steps of a whole inch. The 5″ and 6″ sizes have been almost killed by the rise of the paint roller. It hardly matters for do-it-yourselfers. The wider the brush the greater the demand placed on rarely-used muscles in the hand: the weekend painter is generally more comfortable with a 4-inch brush, and women often prefer 3". Wall brushes are used for walls, ceilings, siding, and floors. They have a square edge.
These brushes are made in three styles: round (½ to 2 inches in diameter); oval, and flat (1½ to 3 inches). They often have a chisel edge. A 1-inch chisel edge brush would be a good choice for trim; a 2-inch chisel edge could be used for doors, shelving, and window frames.
Flat 2″ to 3″ brushes. Be sure the composition of the bristles is compatible with the varnish. A brush used for clear varnishes should never be used for paint, since it is impossible to clean all the paint pigment out of a brush. By Murphy's Law, some will come out into the next varnish coat.
Very wide brushes, 5″ or 6″. Unlike any other type, for this purpose a cheap brush is a good idea.
Copyright © 2000 Sizes, Inc. All rights reserved.
Last revised: 25 March 2008.