Although Redwood has the highest decay and weather resistance of any commercially available softwood, its appearance and longevity can often be enhanced by the use of penetrating oil sealers, especially in sites with high sun exposure. Left untreated, redwood weathers to a dark “driftwood” gray, when exposed to rain. In sheltered locations, where oxidization is not subject to “rinsing” precipitation, redwood typically weathers to a dark brown.
The proud owner of a new deck invariably wants to preserve its “just-installed” appearance. In practice this is difficult: even with annual application of a transparent sealer, redwood will eventually turn gray. Sealers with pigments or colored sealers, will typically last a little longer, between 5-10 years. If using a clear finish, every 5-8 years or so, a light sanding will be required to knock off the layers of the sealer and dirt to once again expose the decks beautiful original color. Redwood sealers also provide several non-cosmetic benefits as well: water repellents slow down the seasoning process, fungicides reduce the growth of decay organisms, and UV inhibitors help prevent the breakdown of wood fibers by sunlight.
Types of Sealers
All finishes sold in California are required to meet strict and changing VOC (volatile organic compounds) compliance standards; brand performance can thus vary from year to year. Select a product that contains water repellents, fungicides and UV inhibitors. The California Redwood Association recommends several brands, including Penofin, Preservawood, TWP, Cabot and Olympic. We carry TWP (Total Wood Preservative) in Clear, Redwood, Dark Oak and Light Cedar colors. It has passed the standards of our harshest critics- our customer’s. No complaints so far in the seven years we have carried TWP!
Pigments help sealers protect wood from UV rays; in general, the more pigment, the greater the UV protection. Truly “clear” products are usually reserved for interior use, although they are perfectly fine to sue outside, they will just require a little more maintenance. Solid body stains offer the highest level of protection, albeit at the expense of “naturalness.” For fences in strong sunlight or high atmospheric pollution, they can be a practical solution, and have a maintenance cycle of six to ten years, whereas transparent stains last only a year or two.
All sealers penetrate further into dry wood. After installation of green or unseasoned redwood lumber, wait four to six weeks to reduce surface moisture. By then enough moisture will have escaped for the sealer to penetrate and adhere. Kiln dried lumber will absorb much more of the sealer, but most people feel the additional cost is not worth the added benefit.