
Watercolor
brushes typically have long, absorbent hairs and the best ones are made
of natural fiber. By tradition, a watercolor brush has a short handle,
since the artist executes fine detail and works close to the paper or
medium. High-end watercolor paint brushes, such as Kolinsky sable
pointed rounds and red sable rounds are prized for their ability to keep
a fine point, useful for detail work. The cost and scarcity of
high-quality natural fibers has fostered the development of good
synthetic alternatives. Synthetic watercolor brushes can be used with
other media.
Brushes used in watercolor are usually made of soft hair, although
bristle brushes are occasionally employed by some painters. Pure red
sable watercolor brush are universally considered the best since they
are soft, resilient, and have excellent points. Well-made red sable
brushes are very expensive, but substitutes, such as "camel hair"
brushes, exhibit noticeable differences which make them harder to
control. Fine sable brushes may be purchased in quill mounts without
wooden handles, as well as in metal ferrules, which are attached to
handles. Watercolor paint brush shapes usually found in a
watercolorist's arsenal are rounds, flats, mops and riggers.

Brushes
used for acrylics have long handles that allow the artist to work at a
distance from the canvas. Acrylic paints are more caustic than oils, so
acrylic brushes are designed with synthetics and bristle. Acrylic
brushes are usable in other mediums, particularly oils, while brushes
designed specifically for oil painting and watercolors are unsuitable
for acrylics. Artists can very effectively use glazing and layering
techniques when using acrylic brushes.
Both natural and synthetic bristles can be used with acrylics,
depending on the artist's preference. But, acrylics, being alkaline in
nature, can be hard on natural hair brushes. Those made with high
quality synthetics have excellent durability and offers excellent
stiffness, snap and hair shape retention for maximum control. The
brushes must be kept clean. If acrylic paint dries in a brush it is very
hard to get out without using strong solvents that might damage the
brush. Brushes are cleaned promptly by washing them with warm water and
mild soap when finished painting.