I’ve discovered a way to revitalize a good, but neglected, brush:
1. Soak the brush for about 15 minutes in rubbing alcohol.
2. Rub the bristles in the palm of your hand, working the hardened paint loose.
3. Wash them in soapy water and let them dry.
Every brush I’ve treatedsynthetic and naturalhas come spotlessly clean down to the ferrule and handle. But I don’t recommend this process for costly, soft-haired or kolinsky brushes.