"The main trick with cleaning your makeup brushes is to be sure you are washing them often and that they lay down flat to dry—never leave them standing up when wet.
Makeup tools should be washed weekly, with the exception of brushes or tools that touch the eyes, which should be washed more frequently. I like to wash my synthetic brushes immediately after use so that when I go back to use it the next day they are dry and ready to go.
I use my Brush and Sponge Cleanser to wash my brushes, which is formulated to help destroy bacteria. Just run your brush or sponge under water to get it wet, spray on some of the cleanser and work it into lather, massaging the bristles thoroughly. Rinse under water and repeat again if necessary. Lay them flat to dry overnight."