This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
All brushes should be washed in benzine or turpentine and shaken dry—not whipped—when it is desired to change from one color to another, or from one varnish to another.
A good remedy to restore lettering brushes which have lost their elasticity and do not keep a point, is as follows:
The bristle bunch of brushes is bound with rope so as to keep them together for use. Instead of the twine, a covering of rubber may be employed, which is easily slipped over the bristles and can be conveniently removed again. The cleaning of the brush is much facilitated thereby, and the breadth of the stripe to be drawn with the brush can be accurately regulated, according to how far the covering is slipped over the brush.
See also Cleaning Preparations and Methods.