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After Deck Cleaning: Gray!

15K views 27 replies 12 participants last post by  Jose Azcue 
#1 ·
I've cleaned this deck about four times now and I'm left with the Gray. I used bleach and tsp, bleach and fresh tsp and even a brightener. Nothing has helped. The last time I did it looked pretty good wet. But when it dried it looked Gray. It's clean but it's Gray. I'd say it's got too much Gray to take a semi transparent stain. Unless it would be Gray or white. When it was wet with rain it didn't look good.
 
#5 ·
No, I didn't power wash it, I don't like them. I used a brush on a pole. The last time I used a hand abrasive scrubber on my hands and knees. I can't remember the name of the proprietary brightened that I used, it came in about a quart sized cylindrical "can".
 
#11 ·
No chemical is going to remove it? But that is the purpose of some of these chemicals e.g.. Gemini Brightner and oxalic acid. I know there's a chemical out there that will do it.

In boat maintenance, there are 2 part cleaners, where the second part is the brightened. And they do work. I'm not sure what the exact chemical is.
 
#12 ·
Grey wood is not only the color of the word, but a term to describe wood fibers that are "dead." It's a protective mechanism that sun exposed wood surfaces exhibit. Grey wood does not accept stains or paints well. Chemicals, even after they dwell on the surface and are hand brushed off, can't remove these dead fibers.
When wood is visibly grey, like I think you are describing, and as has been mentioned before, you have to either mechanically remove (mechanical sanding with sandpaper or Osborne brushes) or use the correct chems, at the correct strength (usually not stuff from the paint store) applied through a pressure washer. Best of luck to you. Decks are a pain.
 
#13 · (Edited)
Light surface graying can usually be removed with a high quality/high concentration oxalic/citric acid product, but on severely neglected decks the graying is a lot thicker than most acid brighteners can handle. At that point it is the best bet to sand the wood until it is a natural wood tone again. BUT after sanding to that point you SHOULD still use a good highly concentrated oxalic acid brightener to make sure the dead wood fibers that have been shoved into the good wood are removed. Another option after sanding is to use a hydrogen peroxide type cleaner as they actually foam the dead fibers out of the grain of the good wood.

(by saying high quality/high concentration oxalic acid/citric acid product I mean NOT something you can buy from a box store! Those are made so diy'ers won't hurt themselves but they can still feel good about "prepping" the surface correctly. Basically it is a huge add on sale at a huge mark-up because they are typically 90-95% water.)
 
#14 ·
another point here. The Gemini deck brightener is an oxalic/citric acid type product, but the msds sheet says it is >50% citric acid and <50% oxalic acid? Kind of vague isn't it? So what they are saying is you "brightened" the deck with something that was 99% lemonade crystals and 1% oxalic acid? Could have just used Country Time lemonade mix for a lot less! Something smells fishy here.
 
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#16 ·
The problem with advising a DIYer (no offense) to pressure wash a deck is that they do just that--PRESSURE WASH a deck. Most have zero concept of "gating back" the pressure by using different tips. The 4 that came with your pressure washer are generally bad news for wood.


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#17 ·
I'm not a big fan of powerwashing decks in general. There are an awful lot of "pro" guys that do the same thing. It takes some skill. If something can take the paint off of a car it isn't a good thing to use on wood!
 
#19 ·
Again, no offense and did not mean you specifically. There ARE many DIYers that stumble across professional forums every day.

I generally use a 4000 psi--4 GPM machine. Using a 40 deg. tip made for an 8 or 10 GPM machine will give you approximately 700-1000 psi (the sweet spot for removing gray without fuzzing or causing irreparable damage). Sodium percarbonate (similar, but somewhat stronger than Oxiclean) is also very useful for removing grayed wood fibers.

Generally, only the more upscale clients (in my area) are willing to pay the labor involved in extensive sanding.


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#23 ·
I wasn't referring to the 35% hydrogen peroxide you get at Walgreens Btw. I was referring to industrial concentrations of it, which are very hard to ship in large quantity's as it is a hazardous material. Sodium percarbonate products sold to regular consumers are not as concentrated. But they are safe for general consumers to use because the hydrogen peroxide generated is a much lower concentration. Sodium carbonate (soda ash) would only be beneficial as a mild and weak abrasive.
 
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#25 ·
Some companies are even cleaning roofs with oxygen bleach. It's not nearly as strong as the (strong) hypochlorite solutions normally used for that application, but it does kill mold and it's SAFE for plants, etc. Vegetation kill (grass, shrubbery, etc.) is big deal in roof cleaning.

I've cleaned decks, etc. with sodium percarbonate with good success. It just requires more manual agitation and more dwell time. It obviously has its limitations though.


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#26 ·
I had a little success today

I bought some oxalic acid online and put it on this morning, mostly cloudy threatening to burn through, coolish hottish very humid and mixed it with hot water at about the rate of 1 pound to 1 gallon of water, 1 pound being 16 ounces. The result afterwards was a pretty natural color wood, much better than it had been. But I'm still afraid it will turn gray again when it dries.

Now the gray that I started with was a very light gray, almost looked like a gray stain. And it might have even taken the redwood stain that the customer has selected. But gray it was when it was dry. I'll see what I have when I return later. Thanks for all the help and the support.
 
#28 ·
After I used the oxalic acid, it turned gray when it dried. About three or so days later, I stained it with Depot semi transparent. And of course you find out that Depot has three levels of stain transparency, until then, I thought there were only two: solid and semi. And it made me look dumb in front of my customer. But never fear, when I picked up stain this morning, the person at Depot didn't know either. I had to inform him.

I found the staining pretty difficult. Really good conditions would help. Today I had it pretty good - mostly cloudy and warm and humid. Thankfully I finished before the sun came out. (I'm in Baltimore). I tried a few different systems and approaches. And made some pretty dumb mistakes. I don't know how you could get it in one coat.
 
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