Thoroughly soak the brush under lukewarm – not warm – water. However, be careful not to get the brush handle too wet, or it could become unstuck in the long run. Apply a few drops of mild soap, possibly neutral, to the bristles and massage them gently. Rinse thoroughly, making sure that there are no soap residues left between the bristles. Dab the bristles with a cotton cloth and allow to air dry; do not use a hair dryer and keep the brush away from intense heat sources.  If used daily, the brush should be washed at least once a week; if used only a few times during the week, it can be washed every 10 days.