Natural bristle hair brushes are similar in make-up to human hair. Because of this, natural bristle brushes tend to absorb oil from the hair, as well as dirt. When oil and dirt are left on a natural bristle brush, they end up being redeposited onto the hair and scalp each time the hair is brushed. For a longer-lasting natural bristle brush and healthy hair and scalp, natural bristle brushes should be washed regularly.
Run a comb through the bristles of the brush to remove hair.
Fill the bathroom sink with warm water and a capful of shampoo. Mix with your hands to create a soapy solution.
Soak the natural bristle hair brush for up to 30 minutes so dirt and oil can loosen from the brush. Rub the heel of your hand back and forth over the bristles of the brush, then dunk the brush back in the soapy water.
Rinse the brush under warm water. Press a clean towel into the brush's bristles. Lay the brush, bristle-side down, on a clean, dry towel and allow it to dry overnight.