The working end of the brush contains the hairs or bristles that compose the head. Just like people, different brushes have different types of hair (or bristles). In general, use softer hair for thinner paints and stiff bristles for thicker paints.

Brush hair can be classified using a number of criteria: length, diameter, synthetic or natural, colour and general health all make a difference to quality. Other criteria are more specialized.

For watercolours, the hairs must be highly water absorbent yet able to hold their shape. For oils, hog bristles should ideally have split ends, called flags, which make for better brush strokes. For acrylic, whether the hairs are soft or stiff, they need to be durable.

Brush hairs need grooming. Hairs are combed and cupped after sorting, tied into bundles of appropriate sizes and inserted into the ferrule. Cupping involves arranging the hairs into the shape suitable for the finished brush; flat, oval, pointed or
other shapes.

The handle may not seem like the most important part of the brush, but it is vital to working comfort especially if you are spending long hours painting.

The length of a handle is traditional. Watercolour brushes generally have short handles for use while sitting at a horizontal work surface, while oil painting brushes have long handles to enable the artist to stand back from the easel, plying the brush with free strokes.

Look for a brush whose handle has a good balance in the hand, has a smooth finish and is the right length for the way in which you work. Brushes are made largely of wood, which can be painted, varnished, enameled or left natural. Some brushes now come with plastic handles.

Once the hairs have been sorted, prepared and inserted into the ferrule, they are then mounted on to the end of the handle with glue to further hold them in place.

The ferrule is the metal section that is used to clamp the hairs or bristles to the end of the brush handle. This should ideally be made of a non-corroding metal. Many brushes have no seams in the metal, however, a brush with a seamed ferrule should work fine as long as the seam is tight and does not loosen up with use. Brushes with very soft hairs may lose them over time from wearing against the edge of a metal ferrule. Many oriental brushes made of very soft hairs are made by tying or sewing the hairs onto the end of a wooden handle. Ferrules were originally made of the quills from bird feathers of varying sizes.

One major thing to keep in mind about the anatomy of the brush is how it is affected by the way you use and care for it. The head, ferrule and handle are all subject to injury if abused, just like human anatomy! Soaking for too long in water, especially hot water will strip all the oils out of natural hairs and bristles. It may corrode metal in the ferrule, loosen glue and cause swelling of the wood in the handle (then when the wood shrinks again, the ferrule will have loosened.) This is but a selection of the evils that can befall a brush whose anatomical needs have been overstrained!