Re: Cleaning Cedar shingles
how high/ steep is the roof? i.e., is brushing with a stiff push broom feasible or do you need a chemical only solution?<br /><br />Take a look at the following article about wood cleaning in general. It focuses on decks, but the same principles should apply. Current general consensus (from a number of articles including the linked one) seems to be that sodium percarbonate (oxygen bleach) based formulations are better then chlorine bleach based formulations for a number of reasons, one of which is that bleach cleaners can damage wood by weakening the lignin in it (lignin if the material that holds the wood fibers together).<br /><br />
www.fpl.fs.fed.us/documnts/pdf1998/ross98e.pdf+Oxalic+Acid+wood+formula&hl=en]Article on cleaning exterior wood[/URL] <br /><br />You can get ready to mix sodium percarbonite based formulations from hardware stores, or make your own. A receipe I've seen is to mix 3oz 100% sodium percarbonite and 2 ozs of TSP to 1 gallon of HOT water. Let the solution desolve for 5 minutes or so, spray onto the wood, let sit for 10-15 minutes, and rinse off. If feasible, brushing with a stiff push broom before rinsing would certainly help the result. <br /><br />Note: don't bother with TSP substitute, which is sodium carbonate, which is already included in oxy bleach formulations. Also, TSP tends to 'rough up, or take the sheen' off painted surfaces, great if you want to paint over something (it'll help new paint stick) but not so great otherwise. I'd think just using the oxy bleach solution might be satisfactory in most situations since the sodium carboniate acts as a 'detergent', but if you want more oompth I'd guess that a small amount of any non foaming detergent would be a good alternative to the TSP. <br /><br />If you go up on the roof, be careful & use safety equipment as the solution can be slippery. If you use a power washer, make sure you spray directly down the roof line; you don't want to force water under the shingles!<br /><br />If you make your own solution, note that different oxygen bleaches contain different proportions of sodium percarbonate, with the rest of the product usually comprised of sodium carbonate (soda ash). You can get an almost 90% sodium percarbonate product online (see link below), but it's pretty expensive. The best I've seen that you can get locally (and probably the best buy) is Shout Oxy Power which is quoted as being 75% percarbonate in the first link, and almost 97% percarbonate as determined by a scientific test project (2nd link).<br /><br />
Hy-Tech Oxygen Bleach page llisting some percarbonate %s by brand <br /> <br /><br />
Some percarbonate percentages by brand as based on a chemistry project <br /><br />I don't know anything about sealing, but would think that there would be an appropriate product for cedar shingles, both to keep out water, and to minimize UV damage. Perhaps there is something that prevents water from getting into the shingle but allows vapor out of the shingle (kind of like the principle for GorTek?).<br /><br />Try a google search on cedar shingle maintenance. Or take a look at Cabot Stains web site and give their technical support line a call. I'm really impressed with their products.
