By: Paul Bianchina
Q: We just cleaned our cedar deck with a product that smells like bleach. We also used a pressure washer (before reading in your column that we probably shouldn't) and now the deck is gray and fuzzy. We also put on a coating of Thompson's Water Seal, but it didn't help. Is there anything we can do now to make the deck look better?
--Gary B.
A: Your first step is to remove the gray appearance and the fine, fuzzy layer - which is actually wood fiber that's been torn up by the impact of the high-pressure water. Depending on the severity of the "fuzz," you can do this with a stiff nylon brush, or you may need to actually sand the deck.
If you have to sand it, first make sure the deck is completely dry. Then I would suggest starting with 40- or 50-grit paper and working up to 80- to 100-grit. Don't go any finer then that, as this will actually smooth out the wood too much and lessen the ability for the finish to penetrate. Depending on the size of your deck, you may want to use an electric random orbit sander, or rent a larger flooring sanding and then use the random orbit to finish up in those areas you can't get to effectively with the larger machine.
Remove the sawdust with a soft push broom, then follow with a leaf blower or similar blower to get the wood as clean as possible. Finally, I would recommend a penetrating stain with UV inhibitor that is formulated specifically for decks. Talk to the folks at an experienced paint store for their recommendations (I would typically avoid the home centers for advice on something like this), and be sure and tell them about the Thompson's, since that may affect the penetration of new product you apply.
Initially, you will probably need two applications of stain to get the color and protection you want. After this initial treatment, in the future I would maintain the deck with a fresh application of stain every two years.
Q: I have a large, ground-level cedar deck and prefer not to use any harsh chemicals to clean it, since I have flowers and other vegetation around it. Can I use vinegar and water, or perhaps a biodegradable soap? Thank you.
--Barbara D.
A: For periodic light cleaning of your deck, I would suggest trying a powdered, biodegradable laundry soap mixed with water, applied with a long-handled, nylon brush. Sweep the deck first, and try not to overly saturate the wood while cleaning. Rinse with clean water, using a garden hose with a wide spray nozzle.
After the deck is clean and dry, I would strongly recommend treating the cedar with a penetrating stain with UV inhibitor. This will maintain the deck's color, and will help prevent breakdown of the wood fibers (fibers that break down will trap more dirt and over time will make the wood harder and harder to clean). Incidentally, there are a number of colors available in penetrating stains, ranging from natural for new decks to gray, which is ideal if your cedar has grayed over time and you like that tone.
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