the baby shampoo does the trick really well along with defogging the mask also. No need to prepare any sort of special formula or spend extra money.I use Johnson's baby shampoo diluted down. It's the only commonly available product that I've tried that doesn't give me horrible skin rashes. Otherwise, local dive stores sell a powder which needs to be dissolved in water. Also effective and doesn't cause any problems. However, I am not carrying a tub of unidentified white powder across international borders!