Prior to staining a wood deck it is necessary to properly clean the wood for the best results. Removing all the dirt, mold, mildew, and graying will help the new deck stain to penetrate better and last longer.
When dealing with a deck that has an old failing deck stain on it, a simple wood cleaning is not enough. In this case a deck stain stripper must be used to emulsify and soften the old stain so it can be removed more easily. Wood stain strippers are more aggressive than a typical wood cleaner.
Some of the best deck stain strippers that we have found contain a mixture of Sodium Hydroxide and other surfactants and typically come in a concentrated powder formula. Once mixed with water they can be applied using a pump sprayer.