Lettering brushes typically have very long hairs, generally of natural fibers, although the scarcity of some natural fibers has fostered the development of synthetic alternatives. This long hair gives them high color carrying capacity, useful for producing large block letters with a single stroke.
Soft natural fibers, such as squirrel and sable, perform best on smooth surfaces such as glass, plastic, vinyl, or metal. For abrasive surfaces, such as rough wood, ceramics, or acrylic primed canvas, choose a brush with a more durable fiber, such as bristle or synthetic. Soft hairs deteriorate rapidly on a rough surface.