Squirrel Brushes have great carrying capacity for thin watercolors and inks. They are used in both lettering and washes. A very fine, thin hair, taken from squirrel tails, squirrel hair points as well as Kolinsky, but has very little "snap" because the hair is not very resilient. Both the Quill, a lettering brush, and the Oval Mop, a watercolor wash brush, are traditionally made with squirrel hair.

Gray squirrel (Talayoutky) and blue squirrel, most highly in demand for lettering brushes and quills, are native to Russia and are nearly always in short supply. Brown squirrel (Kazan) is more readily available, and is used mainly for watercolor brushes. Goat hair, harvested from domesticated animals, makes an economical alternative to the squirrel mop brush, for those concerned about the trapping of wild animals.