Natural brush bristles are made from a variety of materials, including animal hair, vegetable fibers and feathers. The type of material used for a particular brush depends largely on a given brush's intended purpose, whether it is for cosmetic, painting or cleaning uses.
Ox hair is a popular material for painting. It is generally used on medium and flat-shaped brushes and is sometimes blended with other types of animal hair to increase a brush's resiliency. Gray squirrel fur, on the other hand, is used for lettering brushes and quill pens. Bird feather brushes tend to be used for makeup application. Boar's hair, meanwhile, is used for many hairbrushes.