There are a few ways to clean hair brushes with ammonia. One way is to place the brush in a bowl of water and pour enough ammonia over the bristles. Let the brush soak for about 10 minutes, then use a cloth to dry the bristles. Another way is to place the brush in a bowl of water and add enough ammonia over the bristles. Let the brush soak for about 10 minutes, then use a cloth to dry the bristles.