after bodywork and prep are all done , when your about to paint ,hit it with some (dupont)first kleen for the first lifting of grease and grime. then use(dupont) final kleen for last shake down before you spray your sealer(which you should always use in my opinion when doing a full car or any piece with bodywork, basically unless im blending something i always use sealer, saves material and time cause color covers better over sealer than an opposing color). final kleen has a quicker flash time so make sure you rub on and off quickly. and i never use soap..