Is your deck stained? Your photos look to be showing tannin staining more than mold/mildew. Cedar is especially susceptible to tannin staining when a chemical is used to clean it. Those chemicals change the pH of the wood and draw the tannins to the surface. They follow the grain pattern and can look dark blue, black, or gray. You may have gotten rid of the mold, while at the same time bringing out those tannins. It usually takes a neutralizer wash of some kind to get rid of the stains, but can sometimes require sanding to get rid of them. What kind of cleaner are you using to get rid of the mold?
As for the problems with mold, is your deck exposed and in the sun a lot? It's possible some of what you're experiencing is algae, not mold. Not sure where you are in the country, but we're finding more and more of the mold-looking issues are actually algae. Do you have any pics before you washed?
--- Charis w/ Sashco - www.sashco.com - firstname.lastname@example.org
Sure thing. When you do get around to things this summer, be sure to keep in mind that most cleaners will discolor cedar. It usually takes a secondary neutralizer to bring the color back to normal. Check with the manufacturer of the cleaner for specific advice when using on cedar.
And, of course, let us know how things work out.
We have an oxygenated bleach cleaner call CPR that might do the trick. On most cedar surfaces, it's fine, but it can discolor red cedar some. I'd recommend you do a test in an inconspicuous area (maybe on the underside of a board or a hidden corner) to see what happens. If it brightens the wood some and doesn't turn it dark, you'll be good to go. If it does turn dark, you'll need to hit up your local paint store for a deck cleaner and neutralizer.
Let me know where you are in the country and I can direct you to the reseller nearest you.
Hey, Rodney. I ran your pics by our R&D team, just to make sure about what we were seeing in them.
Really, what you're seeing is typical of a clear deck stain. It wears very quickly, leaving parts of the wood bare and others protected. The bare wood gets degraded by the sun, darkening it some. Then, when the wood gets wet, you see it darken (very similar to when concrete gets wet). Where the wood was exposed, that is even more pronounced.
You have a couple of options:
* Clean the deck good and coat it again with a deck stain. Those sunburned areas that have gotten darker will soak up the stain and stay a bit dark, but you'll be protected. (This is the less-work-now-more-work-later option.) OR
* Take everything down to bare wood with a floor sander and refinish. This should help alleviate the darkening quite a bit (although not completely). We'd recommend you use a pigmented stain that will erode over time, rather than a clear that will simply get burned off and offer no protection within a matter of months. A pigmented, eroding type of stain will wear better over time for easier maintenance. It won't completely deteriorate (as a clear often will), nor is it too thick to cause peeling. And just keep in mind: you'll likely need to do maintenance every 1-2 years on a deck that's fully exposed to the elements. :-) Nature of the beast. (This is definitely the more-work-now-less-work-later option.)
That should be enough for you to chew on for a bit. Let me know what other questions you might come up with. Definitely wait to do any work until you can guarantee dry, warm weather (above 40, including overnight temps) to give the stain enough time to dry.
Thanks! --- Charis
No need to use a cleaner or neutralizer first. As I mentioned in my previous response, we're pretty sure that's not tannins but actually just UV damaged wood that turns dark when it gets saturated. Sanding will help reduce that and even things out again, as will using a pigmented deck stain.
So sorry to hear about your wood floor! We recommend folks try to seal roof penetrations from both sides, along with checking their insulation levels, to prevent ice dams. Do you have an attic, or vaulted ceilings with T&G boards? If you have the vaulted ceilings, you might consider having your local energy provider do an energy audit for you since installing insulation isn't really an option. They can often pinpoint where the air leaks are happening so you can seal those up, thus preventing the heat escape and subsequent ice dams. (And I would be remiss if I didn't mention that we make a great roof sealant called Through the Roof that is great for sealing roof penetrations.)
Hope that helps for now. Best wishes with both projects.
Enjoy the Easter weekend!
Wait no more than 2 weeks, if you can. The wood can start building up the sunburned wood fibers in as little as 7 days, so 2 weeks is a max.
Yes, a floor sander will make everything go faster, though not necessarily a brand. Stick with an 80-100 grit sand paper to remove everything. You can usually rent those from home improvement stores. I would think that the Sikkens can have universal pigments added to it to tint it and give you the UV protection you need.