If not rinsed thoroughly the residue can eventually cause a greying of the surface. A detergent must be added to remove dirt. Sodium percarbonate products use oxygen bleach to remove mildew and reportedly avoid many of the disadvantages of chlorine-based products. The third type uses oxalic acid and is recommended for cedar and redwood decks in which water-soluble resins can discolor the surface. Since it is not effective at removing mildew it needs to be used in combination with one of the other type washes.
Power washing is also an effective alternative to chemical deck washes.
It can be effective in removing dirt, mildew and even previous coatings. However, if not used properly power washers can damage the wood surface, as well as adjacent windows, doors and siding. Back to 'Siding and Other Exterior Surfaces' Index You are the 674th access to this page.