A customer wants me to power wash this fence for her. i haven’t done much wood restoration but i’ve read up as much as i can. I just need further confirmation from you guys if this needs oxalic acid, f-18, or f-8? or do i need to green tip the whole thing. all my fence cleaning has just been old dirty fences.
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i can provide a little more pics if needed
Do not green tip it. I would pre wet, hit it with 1% SH w/ surfactant, dwell 10 minutes then soft wash it. Don’t let it dry before you rinse. You can use oxalic after you’re happy with the look.
ill try a test spot with 1% SH and elemonator. I don’t have oxalic acid at the moment but i DO have f8 wood brightener, would that also work?
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It’s concerning that you aren’t even aware of the chemicals that are in your repertoire. You say you don’t have Oxalic acid but then you say you have F8. Which is it?
I’d start at 1% but would go up some if needed. It’s a fence so you don’t have to worry about furring quite as much as if it were a deck. After dwelling hit it with around 1000 psi. I usually use a 40 degree tip and keep it close enough to where i only do one board at a time. Maybe a tad more to try and hit the adjacent side. I would think brighten with oxalic or citric acid. I prefer oxalic though, Oxalic is only used after cleaning. It won’t clean algae or mildew off a fence.
Btw, a green tip can be any pressure depending on the orifice size.
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I have F8, which has oxalic acid in it.
What should the end result be looking like? it doesn’t look like it’s organic growth as much as old paint? Should it come out as that darker brown you can see in the 2nd pic, or as the lighter brown you see in the 1st pic?
F8 is just a name brand. It’s just Oxalic acid. Check the SDS. So, yes, you have Oxalic acid.
gotcha. it is hard to keep up with all this stuff sometimes 
I couldn’t remember if it was f18 or f8 that had the oxalic. thanks for making me run out to my garage and check 
Looks like mildew to me. You can find out by doing a small test spot in an inconspicuous spot with a strong mix. Hit a small are the size of a half dollar with 4%-5% and it’ll kill it fast. Just be ready to rinse it right away. I mentioned using a stronger mix than 1% because it’s so filthy. I don’t think 1% will touch.
Do you know which nozzle you need to get the 1000 -1200 psi? When you pressure wash it start at one end and continually go to the opposite without stopping so you don’t leave lines. You’ll only end up being maybe 4" away from it if you hit one board at a time. It doesn’t take long to wash a fence though.
How can i get over 1% from my machine? the most i could theoretically put out is 1.25% or so. or are you saying to pump spray / 12v it?
Yeah, I hardly ever down stream decks unless it’s not that dirty. I don’t like using my actual 12v because I hate having to mess with it for 5 minutes worth of spraying. I either use a pump up or, if it’s a larger job, I pull out a small portable 12v unit I threw together. If it’s a really large job I’ll use my actual 12v. Another reason I don’t like using my main 12v is I feel like I waste about a gallon of oxalic when I go to flush just because the 225’ of hose holds so much. My portable 12v has 50’ of 1/4" hose so I can pretty much leave it in one spot when spraying.
Ok got it. so try a hot mix in a small out of sight area, then find out how hot i have to go for results. Then spray 1.8-2% SH & Surfactant around (just a guess), dwell for 3-5 minutes, then 1000 psi one board at a time, fluent sweeps without stopping. After that i apply f8 as stated in their instructions? @marinegrunt
My pump up sprayer would take 5-8 years to clean this fence
You don’t really need to do the test spot with hot mix. I just mentioned to try that if you really think it’s painted. A 2% mix should be strong enough to let you know if it’s organic. I would let it dwell longer than 3-5 minutes but just make sure you keep misting to keep the wood wet. You’ll be able to tell how long to let dwell or if you need to spray another application or two of mix by the look of the mildew on the fence. I would probably do at least a 10 minute dwell unless it looks clean enough to rinse,
That pump sprayer should work. I’m not sure how long the wand will last but you can always replace that. You could throw it in a wagon with a battery. I used an old homeowner pressure washing cart. I mounted a 7 gallon blue plastic container to it, added a 1.8 gpm pump, some hose, and a battery.
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Prewet to soften, 2% mix with 12v if you have just to kill anything but you’re going to need to white or green tip it, you need to strip a lot of that dead wood off of it. That’s a definite candidate for just good old pressure washing. Going to be a lot of work, price accordingly. Get you a 4’ or 5’ lance if you don’t have. Going to be messy.
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to get 2% SH i’m debating wether to get a small 12v setup or an x jet. Would an X jet be putting out too much volume for something like a wood fence? something tells me a gentle application with the 12v sprayer would be more efficient and use less chems. I haven’t used an x jet before so maybe i’m wrong.
x-jet with a 4gpm is doable. I haven’t used a 5. But with an 8gpm the xjet is pretty overpowering.
Downside with an xjet is your dragging around a bucket.
If I were you, I’d consider a small 12v setup, even something cheap from Northern Tool to get you started.
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Just a heads up, I used a 12V for the first time last week on a moldy house and was really surprised the amount of solution I went through. I was batching 25 gallons at a time. It went fast, keep moving .
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thanks for the heads up. i’ll be prepared for that
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