This is a Rosco Iddings natural bristle brush. Its bristles are 1.5" long. It can be used on a variety of stagecraft materials, including muslin, canvas, lumber and such non-porous surfaces as plastics and metal.
A 1/4" wide seamless nickel ferrule keeps the bristles tightly bundled for effective use. A polished, sealed birch handle has the right heft for students and scenic artists, and resists wear and damage.
Iddings brushes should be washed in warm (not hot) water immediately after use and rinsed until all traces of paint have been removed. They should be laid flat or hung by the handles for drying. Periodic cleaning of the brush head and soaping the bristles into place after cleaning will aid in maintaining its original shape, prolonging the life of the brush.