I definitely don’t let it sit anywhere, I keep it moving, not fast, but medium speed
Initially we used a strong house wash mix with probably 10 min dwell
When I returned I hit it with a 3% with 5oz/gal sodium hydroxide and a 5-10 min dwell. Didn’t get much better nothing was touching it. Even reapplied in a few of the worse sections
dang, what the heck is it, I bet its copper from pressure treat.
Could be copper, I recently did a fence with the same issue. I do suspect the green algae gets deep inside the fibers though.
I’ve cleaned fences that were 9-10 years old that still had plenty of green from the treatment. Still took stain well though after a few weeks to dry out well
I’ve noticed a few posts of your saying you used a surface cleaner, when do you decide surface cleaner at high psi is better than wand at 800-1000? Posted on deck 101 thread, would love some feedback, been trying to get these down for a few years, not quite there yet. Your results are always incredibly surprising to me every time I scroll down to the after shot.
Also how do you avoid furring, I’ve had terrible furring at 1000-1200 psi and now scrub and rinse with garden hose. Still furs a bit sometimes from scrubbing I’d guess
Wood is going to fur some….it will lay down in no time. I personally don’t go higher than 800 psi., you can go more though on real bad decks. If you leave chem on too long it can cause furring as bad as the pressure sometimes……I’ve done some test pieces over the years….
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First, I don’t think I’ve ever hand scrubbed a deck. That’s what a pressure washer is for.
Why do you leave oxalic on w/o rinsing? All that’s going to do is bleach out the wood more, plus won’t be able to stain over. That’s just being lazy in MHO. I mean looking at all your pics. none would have taken more than 5-10 min to rinse.
Cedar will fur easier than treated pine. You need to knock the bad wood fibers off. With yp you can go up to 1400-1500 psi easy and not fur if you know what you’re doing.
Anytime I use 1000-1200 psi I get bad furring… and when I used to just DS decks they wouldn’t change appearance at all once dried.
Not sure what else to say, don’t quite understand how your decks come up like that with a DS.
And none of these customers planned to stain, almost all old decks. Certainly not being lazy but when it doesn’t seem to make a difference on final appearance id rather let it dwell. Also, many oxalic acid suppliers state that letting OA dry is common practice for wood cleaning.
All opinions aside, what can I do to get a more consistent clean across the deck. Even that greyed deck should have been an easy one and it still dried pretty grey again.
Do you think my chemicals have past their shelf life? Dwelling too long? Or just not using enough pressure…
It’s good practice like @Racer said to do a good rinse, especially when you apply OA….i personally see no need to leave on, it usually does its job 10-15 minutes or less, then flood with water. Most decks I do people plan on staining so good to get that OA rinsed and prepped for stain/paint.
Why are you using OA? Is it to remove rust? The only reason acid is used AFTER the SM,SP, SH, Hydroxide is to balance/restore the PH. Unless there are rusty nails, then oxalic treats the top of the nails (like any acid would to remove rust). I’ve read everything I could find, and I never read to let it dry on wood.
If you are getting furring, join the club. Most decks will fur in the cupped sections or around the knot holes. If you had to get aggressive with chems it will fur. If it isn’t coming clean, then you aren’t using the right mix, not enough dwell, or the wrong tips. 12" off the wood and walk the boards. I’ve never used the SC to clean a deck, and it would have to be a real piece of garbage before I tried it out. I don’t have a system like racer with 16 different SC’s and an assistant handing me each one 
Most of my decks are painted/stained and need stripped. Once in awhile I clean some. WHen the wood is wet it provides an optical illusion allowing you to see deeper into the wood. This is why you see green when it is wet, and when it is dry you shouldn’t.
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Ya perhaps I’ll start rinsing again, if they were staining I would rinse for sure, most of these decks are pretty rough and they just want better so I figure maybe it would brighten a bit more and I will take picture of my 25kg bag, or maybe it was on supplier site. Says let dry
I’m using OA to brighten and neutralize, rust removal is just added benefit imo. And I’ve tried many different mixes to get these old ones clean. Up to 8 oz per gal of SM or SP probably over 30 min dwell, multiple coats. Seems it just doesn’t come up sometimes.
Looking to get better just don’t know what else to try with the products I’ve been using. Perhaps I’ll be trying SH/Hydroxide next time. Maybe start adding more soap, usually put a dash of dawn in but haven’t as of recent, not sure why, running out of ideas.
And I said it in my other reply but will send pic of my OA bag or supplier website. Says let dry for black stains.
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Do you use a different acid? Also do you scrub after the Sh/Sp or whatever you use to clean? I just saw that racer said he doesn’t. I usually do to aggitate but that’s only on decks that have a good build up on them
If you aren’t removing rust, citric is a viable alternative. It smells better too.
OK, I got some time today so here comes a wall of text.
Well, you went about it a little different. If say hydroxide isn’t working at 8 ounce a gal, bump it to 10 or 12 a gal. If that doesn’t work, then up the dwell time with a stiffer mix. Just don’t let anything dry. A scuff test is your determiner, I also sometimes do a test board to see how it is coming. Sometimes I even bump the pressure up a bit, I have two sets of nozzles on a jrod for wood with different pressures. Wood is odd, what worked on the last deck that looked the same won’t even budge this stuff. The deck laughs at you and then tells you that you are an idiot and drastically underbid this job. This is why most people avoid wood, it isn’t as simple as a house wash - spray, rinse, collect check. edit: try using a backpack blower on a deck before you wet it/chem it. I do on every deck. I use a stihl 550 i think, it is a big backpack used by lawncare, a little dinky one won’t do much.
One of the people I got advice from on this forum goes by the handle @MDA1775. He pops on here from time to time. Maybe he will pop in and decide to enlighten some of us, he is a wealth of knowledge.
Soap isn’t a bad idea on verticals, heck soap works on wood too. You need something to help the chems cling to the spindles/posts, otherwise gravity tends to pull it down. If I use something on a strip job on spindles it would be the roof soaps that tend to be a little thicker and cling better. As a guy who used to paint, you can use lots of thickening agents on stripper to get it to adhere.
Surfactant lowers surface tension, grabs the garbage and allows you push it away. No soap, sub standard results for house washes. Not everything on a deck is organic matter that needs attacked by SP,SH, Hydroxide etc, some of it is just dirt. I use a little soap in my mixes, I like the bubbles. If I clean a PVC deck I use soap and SH, why wouldn’t I do it on wood? (I don’t use SH on wood normally). Besides, I know I have rinsed the deck thoroughly when no more bubbles show. Then I get the sad face with no more bubbles. I then cry. Homeowners then grab the blow bubbles and put them throughout the yard and I am happy again running through the yard popping bubbles. That is a funny thought, does not actually happen for those who don’t get humor.
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