like glamyourus and nunu said, DO NOT wet your brush and then dip it into the shadow. when you do this, the water/mixing medium/visine sinks into the shadow and causes bacterial growth. if you continue to use the shadow, you can get eye infections from this bacteria.
if you want to use it wet, dip the brush into the shadow first, then mist the brush with water or fix+.
another option is to buy the hot contrast MES. these you can use a wet brush on without causing bacterial growth.