i've been washing them more routinely lately. i spray clean (i was using Japonesque Parian Spirit, but recently switched to Ulta's brand- but the Japonesque one is better, in my opinion) my foundation, blush, powder, lipstick and eyeshadow after every time i use it and wash once a week. i usually use a clear veggie glycerin soap, swipe it across until the colors have dissolved out. and then rinse.and dry by swiping across a terry cloth hand towel, then hand reshape. either that or baby shampoo.
i spray my big bronzer every time after use, and wash maybe once a month- but when i wash that- it gets the royal treatment. I use Klorane Mink Oil Shampoo.