Wood fence

Question…I have been scouring the site, but haven’t gotten a clear cut answer and have been looking all over the internet (may be a slight exaggeration). If I have 10% SH, what ratio should I use in a pump sprayer for un-sealed wood? Also, I have been hearing that it will make the wood brittle…I understand rinsing extremely well. My neighbor is willing to allow me to use her fence as a tester, but I am hearing completely different variations as to what to use and what not to use. Any advice would be appreciated.

Stay away from cleaning wood with SH. Look into F8 and F18 from Chemicals & Handling - Page 1 - Pressure Tek

There are a few quality you tube videos describing the best practices. I prefer using sodium hydroxide (lye) to clean and 1500 psi to wash followed by oxalic acid to brighten. I get some furring of the wood with this approach but the color of the wood comes out well.

Thank you for the advice…just out of curiosity and since I never did well in chemistry, what is the reasoning behind not using SH? Is it like what I stated, it’ll make the wood brittle? Again, forgive my ignorance.

Also, based on what I am seeing, is this just oxalic acid? If so, couldn’t I simply purchase a smaller container from Home Depot or Lowes? My neighborhood is mostly vinyl fencing and very few wood fences. If it takes off, I would then consider purchasing a larger volume.

For vinyl stick with SH. No oxalic.
From what I remember SH is used in the paper making industry to breakdown the pulp. When applied to the fence it has similar properties.
When I have used SH on pine fences I have noticed the wood is whiter. Not the orange tint it should be.

That makes sense…So what is the point of oxalic acid? I do not want to pressure wash if I do not have to, especially if it can cause furring, but I also understand that some pressure may be needed. Which tip would you suggest?

Sorry, I just looked back and noticed the point of oxalic acid…to brighten. I have done vinyl with SH and it worked perfectly. I think this whole thing with wood is confusing as I believe too much can go wrong.

No way, you got this. Search here and YouTube. As far as the tips are concerned they are dependent on the machine you have. Pressure tek has a nozzle chart you can use to determine the right nozzle to lower the pressure.

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Shoot, I spent about an hour or so on Youtube, last night, but I kept getting conflicting ideas. So, the rule of thumb is no SH on wood…understood. To kill the mildew, oxalic acid? Then I will definitely look up the chart from pressuretek.

Just for clarification, this thread is around 4 years old… I only bring that up so that you know the age of the advice at the beginning of the thread. That doesn’t mean it isn’t accurate, though.

No offense to midwestwaterways, but the guys recommending bleach at the top of this page (everett, rpetry) are two of the biggest names in the wood cleaning industry. There IS a bit of debate about using bleach on wood, but i believe that was mostly in the past. These days it’s generally ‘approved’ for use, at least from what i have seen. Shane Brasseaux is a huge wood guy too, and he uses it.

However, like everything, you must use it properly. Used incorrectly, bleach can produce a bad result.

Now, the recommendation to use 50/50 (which would be 6% if using 12.5 bleach)? I’ve never seen a pro recommend that strong of a mix, as rpetry pointed out. Generally 2% is recommended, although rpetry says 3% max.

So if you want a 2% mix and you are using 12.5% strength, you add water to dilute it down to 2%.

When figuring mixes, a lot of people just use 10% in the calculation, because it’s easier to figure, and unless the bleach is brand new, there’s a chance it’s down around 10% anyway, because of how fast it degrades. Using 10% in the calculation, you add .2 gallons of SH to .8 gallons of water for a 2% mix. So 5 gallons of 2% would be 1 gallon of SH to 4 gallons of water.

If you want to use 12.5% in the calculation, you would use a little less bleach.

F8 and F18 is another great combo to use. This is generally used when stripping a stain, however, it is also pretty effective when you dont have to strip… you just have to be careful with how strong you make it, and how long it dwells, as it will fur the wood if left too long.

Use appropriate nozzle to produce around 6-800 (ish) PSI for cedar, and 1000-1200 PSI (ish) for pine.

Full disclosure: I’m no expert, I learned this information from reading the input of others, like @Racer, and practicing on old wood.

This can get you headed in the right direction, but you need to do a lot more research… there are tons of discussions on the web that will answer your questions. It’s going to take more than an hour on youtube. Join some of the Facebook groups, and search for ‘deck’ or ‘fence’… there are many many conversations about wood there.

Also, find some old pallets to practice on. Nothing beats experience.

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Thanks man, I truly appreciate your input. I have read some of your other information and appreciate that, as well. I understand everything you are saying and when I mentioned an hour last night, that wasn’t the only night lol. But, like I stated in my original question, I have gotten permission from my neighbor to test on a non-visible section of her fence.

In other news, if I am using 10% SH and I want to make, as you stated, a 2% mixture, it is basically 20% (if I am doing the math out of 100). So in a one gallon jug, approximately just under a 1/4 gallon? Sorry, I always sucked at math, even the simplest. I actually just contacted pressuretek to ask about the nozzles after looking at the nozzle chart.

Again, thank you for your input and I look forward to practicing.

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Cool, yeah if you have permission to practice on a non-visible area that is good. I mean, it’s not like you are going to turn the fence bright blue, or rip it in half, or anything, lol. Worst you can do is scar it up a bit, but with the research you are doing, i think you wont even have to worry about that.

Yes, 1 gallon would be .2 gallons SH, to .8 gallons water. 5 gallons would be 1 gallon sh to 4 gallons water. Might be easier to do that way, and then pour in your pump up sprayer.

I’m going to PM you a softwash mix calculator where you just have to plug in the numbers you want, and it will tell you how much to add. It’s from another forum, so i dont want to link it here. Anyone PM me if you want it.

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Again, thank you so much! Yeah, I have a day job, but while my students are working, I’m literally on here reading up on things and trying to take notes, lol. Probably not the most responsible thing, but even when I am not at my day job, I am on here every waking moment.

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Here’s a chart. If you dont already know how to read it, here’s how you do that.

Figure out what PSI you want… lets say 1000 PSI. So find 1000 PSI along the top, then go down the column until you find the GPM of your pressure washer… lets say you have a 4 GPM machine, so you would go to 4.00. Follow that to the left, and that is the orifice size (8) you need to produce 1000 PSI at 4 GPM.

The only other part you need is what degree of fan you want on the tip… 0 degrees is a straight stream, 40 degrees is a wide fan… with 15 and 25 being in the middle. 40 degrees is a common fan size for wood, as it’s about the width of a picket. 25 can work too, though.

Nozzles are identified by degree first, then orifice size.

So if you want a 40 degree tip with an 8 orifice, you would order a 4008.

https://www.powerwash.com/media/wysiwyg/Nozzle-poster_1.png

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Ohhhhh…now that makes sense. I contacted pressuretek and they responded with an even more obscure response.

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The debate ended for me after trying them both. I like the results better using lye, sodium hydroxide. However, restoring wood is as much a science as it is an art. I continue to try different concentrations and or dwell times. If I ever figure it all out I’ll probably get bored.

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What is obscure to one may not be obscure to another.Some vendors use different terminology. Nozzles are typically degrees first, gpm second. 2502 would be 25 degrees at 2 gpm. Buy one of every tip close to your machine size and tinker for what works best for you. I use lye/potash on wood, or did when we did wood.

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Thank you for that explanation. That also makes sense.

@tireshark @John_Martinez Just wanted to give you two an update. I completed the wood fence. I spoke with a local pressure washing repair/retail shop and purchased some of their wood cleaner. It was a spray on, dwell, rinse off solution. The fence came out very well and the customer was beyond pleased.

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