Paint brush bristles or hair have flattened, split ends called flags. The flags
enable the bristles to trap pigment and move it around. The end of the
bristles, enclosed by the ferrule, is referred to as the butt. Here brush
deterioration generally begins with trapped pigment rotting the bristles. When
judging bristle elasticity, you should bend the bristles at a 45-degree angle to
a horizontal surface and observe where the bristles bend. The bend should
occur approximately 1/3 the length from the ferrule. The bend of the bristle
is called a heel. A brush that is too stiff to bend or bends too near the tip is
an inferior brush.
Figure 1-15 shows bristle nomenclature.
Figure 1-15.Bristle nomenclature.
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