Power washing a deck is one way to help prep your deck for a fresh new coat of wood stain, or get it ready for your next event. However there's more to it than just turning on the pressure washer and spraying. Pressure washing can help, but if you want your stain to last, using a good deck cleaner and brightener on the deck prior to pressure washing will provide you the best result. A good deck cleaner can remove the gray fibers, dirt, mold, mildew and other impurities deep in the wood. However, choosing not to stain or paint the deck is simply a preference of the homeowner. The effects that can occur due to a lack of treatment are aesthetic in nature.