Oxygen-based bleach: Deck-cleaning compounds designed specifically for wood commonly contain sodium percarbonate, which is also found in many color-safe laundry bleaches. Sodium percarbonate is a powder that mixes with water to form hydrogen peroxide and sodium carbonate, both of which are very effective at removing gray weathering residue as well as mildew, dirt, and other discolorations. Properly applied, oxygen-based bleach products will go a long way toward restoring your wood deck's original appearance. Cleaners containing sodium percarbonate are effective on most types of common decking woods, and will also work on pressure-treated fir, pine, and hemlock.
Oxalic acid-based cleaners: Another common problem with cedar, redwood, and certain other species is a natural resin in the wood called tannin. Tannins, which are water-soluble and a reddish-brown in color, can migrate to the surface of the wood and be deposited there, leaving dark brown discolorations. Tannins can also react with the metal in the fasteners that secure the deck boards, resulting in dark, blue-black stains that can really mar the appearance of the wood.Deck Furniture, Pool, Home Improvement, Deck Building, Sunrooms, Awnings, Deck Furniture, Pool, Home Improvement, Deck Building, Sunrooms, Awnings