What would you use? Bleach, sodium percabonate, or sodium hydroxide?
I’ve used bleach and percabonate, both with good results but I’m wondering if there would be any benefit to using hydroxide in this situation or similar?
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Using NaOH on unfinished wood is likely to cause the wood to look like a carpet…lots of fibers will come up. I call that the slash and burn technique.
I would use a mix of oxalic and my favorite surfactant.
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I didn’t even realize that was an option. Thought it was just to neutralize concerning wood.
It’s the main ingredient in “WOOD BRIGHTENER”…because it cleans wood very well and brightens it.
P.S. If you plan on staining it after you need to let it DRY for at least 24-48 hours…I know you probably know that but I don’t take anything for granted anymore.
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I knew it brighten it, but I was under the impression it is applied to an already cleaned surface. As the second step. Clean with percabonate or bleach, then oxalic
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The thing is, if you apply SH you have to apply oxalic after anyway to calm to tannins back down.
I’ve used it on it’s own in the lab and it does well…don’t forget to add the surfactant.
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Sodium metasilicate would work great on that
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It looks like old wood. Tell them sh and it might fur up or for more money you can apply fancy chems and it will not fur. Both end with no algae. They always pick sh.
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Chad, are you using powered metasilicate? And what ratio are you using?
Did you mean powdered? Then yes
You can get the ready to go stuff from different places. This one is from Deck Restoration Plus.
You can also buy it in bulk from places like The Chemistry Store. Just add some surfactant
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Ha! Yea, powdered! Thanks for the info!
Not that I would ever argue chemistry with @CaCO3 but heavy tannins are usually associated with “red woods” cedar, red fir etc. Ox works great for dealing with that or iron stains. That deck might be cedar but it looks more like white wood that is in tough shape. I would go with Sodium Percarbonate and expected to do some hand work, followed by oxalic. Pre-wet before applying chems to help keep them on the surface since old wood like that tends to pull it deep into the boards and creates more furring. That’s probably going to have some raised grain where the lignin has been eaten away by UV etc. so set your customer’s expectation. You can make that deck look good but be careful or you will have a mess on your hands.
This might be helpful too: https://www.fpl.fs.fed.us/labnotes/?p=4368
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From the looks of the rest of the property, grass and sidewalk, don’t think you need to overthink it. Use the Percarbonate as Mark suggested. Or personally I would prewet, put about a 1.5-2% SH mix on it, let dwell about 5-10min - rinse with medium pressure(about 1500psi). That looks like yp and will be a 30min job. If they want stained, then neutralize. If you’re just cleaning, don’t worry about.
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Ful strength Oxalic or diluted?
You’re right Rick, the question was so mich for this job as it was for my own continued education. I was curious if there was an easier way. I usually xjet 6% sh without the proportion tips. The 8gpm machine isn’t getting 50/50 draw so I’d guess it’s about 2%. Then I use 4015 tip.
I guess there’s no way around having to pass the wand over every inch. I was kinda hoping for a magic recipe to melt that stuff off and rinse.
I’m pretty sure it was yellow pressure treated pine. I like percabonate, it always produces good results. What’s your recipe and method of application?
Do you but straight percabonate or a product with it in it?
That’s one chemical that I never used. So you revvomemd this over all of the other options?
Potassium Hydroxide mixed with “power solve” downstreamed…dwell 15 minutes…repeat if necessary.
Downstream “citrus pre soak” … wait 2 minutes and then rinse with garden hose.
That’s for decks with no stain.
Decks that are stained use a 12volt and put down a 50/50 mix with power solve as well. Dwell 20 minutes, repeat if necessary. Downstream citrus pre soak …wait a few minutes and rinse. 800 psi may be needed on floorboards, but usually only need to rinse spindles and hand rails, outside of deck. I hate pressure washing decks, I’ll reapply 3 times if I need to.
Especially while washing the house…spray the deck and let dwell so your not sitting around waiting for the dwell time.
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It depends on how bad the deck is and what else the algae etc. is covering up. I tend to go as light as I can on the chems to avoid furring and sanding. I start with 16 oz of OX powder in 2-2.5 gal of water mixed in a pump up and apply (adjust based on reaction). Let dwell and then see what comes off with low pressure, making sure to go from end to end on any board. Sometimes that’s all it takes, as needed I’ll reapply and scrub with a Quickie brush and wash down again. If I find grill related grease under everything, I’ll use potassium hydroxide and scrub what I can out. It works surprisingly well. BTW, I have never “just” cleaned a deck, if someone is having it done here it will be a prep for staining.
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If you find it, be sure to let the rest of us that do a lot of wood know it. You’ve kind of have to knock that dead wood off of there, kind of like taking a shower when you’re real dirty. Sometimes have to scrub a little.
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