The best way in which to clean hair-brushes is with spirits of
ammonia, as its effect is immediate. No rubbing is required, and cold
water can be used just as successfully as warm. Take a tablespoonful
of ammonia to a quart of water, dip the hair part of the brush without
wetting the ivory, and in a moment the grease is removed; then rinse
in cold water, shake well, and dry in the air, but not in the sun.
Soda and soap soften the bristles and invariably turn the ivory
yellow.