These include lettering quills and stroke brushes for sign painting, large round watercolor wash brushes, and china painting bushes. These soft, fine absorbent hairs offer a fine point but little resiliency, so are best used in lighter mediums. Red sable, ox, and camel hair are the broadest groups of natural soft hair brushes. As its name implies, bristle is a stiff hair derived from a hog, pig, or boar. Two characteristics of a quality bristle brush are flagged tips and interlocked construction.
Natural bristle has a split tip called a flag.
The lack of flags on a bristle brush indicates a brush which has been cut, not hand shaped. The bristle desirable for a good artists brush has a natural curve. Today, with the technology to produce a variety of synthetic fibers, synthetic brushes are now the choice for many applications, including fine art. The word nylon is often used to generically represent synthetic fibers. In artist brushes this synthetic fiber is actually a polyester.