Practicing applying wood chemicals on an old fence

Removed a large section of old fence recently, and I am going to use it to practice different types of chem applications on wood. Here is a brief rundown of what i plan to do, based on reading tons of old forum posts over the past few months… any advice on my methods are welcome, such as dwell times or mix concentrations. I know that different situations call for different methods, but this is just a way for me to get my feet wet on what to expect with an average weathered fence, like i have.

Will prewet wood before each application. My rinsing will be done with a 2510 tip, on a 4GPM machine… so around 650 PSI. Oxalic will be mixed at 8oz per gallon.

Not entirely sure of the type of wood (dont really know how to tell them apart yet), might be pine. I did a water test, and it soaked into the wood, so it doesn’t appear to have a sealant on it.


Sodium Hypochlorite: Pump spray a 2% mix of SH with 1oz per gallon Roof Snot added. Dwell 10 (?) minutes. Rinse at 650 PSI. Brighten with oxalic. I will also do this method without an oxalic rinse, to see if there is a difference.

Sodium Hydroxide (100% lye that i bought from TSC… Roebic crystal drain opener): Pump spray 4 oz. (1/2 cup) per gallon of water. Dwell 10 minutes. Rinse at 650 PSI. Oxalic.

Sodium Percarbonate (Wolman’s Deckbrite, that i bought from Orschelns): Pump spray 8oz per gallon of water. Dwell 15 (?) minutes. Rinse at 650 PSI. Oxalic.

Pics of before, with a couple close up of the wood:

Thanks for any input.


That’s what I’m talking about. Good stuff. My only advise would be don’t prewet. It accomplishes nothing except makes it harder for chems to penetrate. Sodium hydroxide can easily be downstreamed on that fence and is much quicker than pump spraying. Good luck and happy tinkering.


Cool, thanks for your input IB… very much appreciated.

According to a lot of folks…this guy is the wood guru.

Here is a recent thread that folks here commented on. He has, seemingly, good advice on properly applying bleach to wood.


Everett knows more about wood than most. He may say to prewet. If so I disagree but I’m wrong a lot and hard headed. Take his advise over mine on wood but experiment to see what suits you.

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I’m by no means an expert and don’t have near the experience some of you guys do but, I love doing wood and have made it a personal goal to be the best at it in my market. I’ve played around with many of the various techniques I’ve read about here. To me, it seems like the wood cleans better if I pre-wet it and also uses less chems because it’s staying on the surface killing the gunk instead of soaking it all up. Also, when I’m cleaning it, I like to use real wide swipes that fade off so that you don’t have “stop marks” in the wood. Kinda like how you would paint with a spray gun. And the single most important thing I’ve learned is ALWAYS start with a weak solution and work up. Every wood project will be different due to wood type, the age and condition, etc. It may take a tad longer however, doing that will prevent damage to your customer’s property.


Good stuff indeed. Look forward to the after pics.

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Awesome. Great way to experiment! Really shows a commitment to learning that others need to emulate. Let us know how each method goes with some pics.


Thanks for the encouragement everyone. Well, the chems have been sprayed, and now we wait for them to dry. Was getting dark when i finished, so i will find out tomorrow how they turn out.

Here are some pics of my “laboratory”, with all my pump up sprayers and chems, hah. I used four sections… one with SHypochlorite, one SHydroxide, one SPercarbonate, and one with nothing to compare. Also threw a tarp over neighboring sections to prevent overspray from drifting over.


Left to right: No treatment, Sodium Hypochlorite (1/2 rinsed with oxalic), Sodium Percarbonate, Sodium Hydroxide.

Summary: All 3 looked similar. The bleach treatment looked slightly lighter in color, while the Hydroxide/Perc were almost exact color. Hydroxide had significantly more furring, shorter dwell time might reduce it. Biggest surprise was how much of a difference an oxalic rinse made on the bleach treatment.

SHypochlorite panel… left side from black tape back had no oxalic rinse, right side did. Side that oxalic was used on looked significantly better:

Close ups of furring. Perc and bleach had essentially no furring, except for a slight amount on two or three boards of the perc treatment. Those boards were overall darker in color too, so not sure what the deal was with them.





Final thoughts: For this particular fence, all three looked acceptable color wise (except for the non oxalic rinsed bleach treatment). Hydroxide and Perc looked best to my eye, with bleach close behind. May try hydroxide with shorter dwell time to see if it reduces furring.

If i had to pick just one method, based on my results with this particular wood, i would probably pick SPercarbonate. Nice color, no furring, safer for landscaping. I havent figured up cost comparisons, though.


(Note: Dwell times were a little longer than i had planned, because i did them all at once, instead of one at a time.)

Sodium Hypochlorite: 1.5% mix (109 oz water, 19 oz 10% bleach, 1 oz roof snot). Dwell time 18 minutes. Oxalic rinse on half.

Sodium Percarbonate: (Wolmans Deck Brightener) 1 cup into 1 gallon hot (tap) water. Dwell time 19 minutes. Oxalic rinse.

Sodium Hydroxide (Roebic Drain Crystals): 1/2 cup into 1 gallon hot water. Dwell time 18 minutes. Oxalic rinse.

Rinsed with 2510 tip on 4GPM machine - around 650 PSI. Oxalic mixed 1 cup to 1 gallon hot water.


Good stuff tireshark. Now since that looks like yp, go back and hit one of the panels with 1500 psi.

With cedar want to keep psi at 1000 or less, yp lot harder so you can go up considerably. Great job experimenting. Most of us that have done a lot of wood have gone through this exercise, but you did much better than most documenting it all.

The fence wasn’t in very bad condition, but you want enough pressure to knock the dead wood off. On this experiment because not in too bad a condition, you may not see a lot of difference, but you will see some. When you get done with that section, it’ll have greenish tint kind of like newer pressure treated.

The fence below was done with with percarbonate and medium pressure on 10 year old fence that had never had anything done to it. As you can see on right side, under those trees, was covered with green mold. Still wet in photo, but when dried almost looked like new PT wood.

Also, unless you have a lot of rusty nail heads, would suggest you use citric acid instead of oxalic. Much better for the environment and not as dangerous to work with.


Thanks for the info Racer! I’ll order some tips that will put me in that range, to use on yp.

Nice result, and great pic with that fence. Does the cleaned section have a stain applied to it?

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Not when pic was taken.

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That’s beautiful, Rick. Couple of questions: @tireshark mentioned Wolman’s Deck Brightener as brand for SP. Is there a more economical source and where would you source citric acid and at what concentration would you mix it?

Oh, and TS, that’s one hell of an experiment. Nice lab.Well done!

When you guys are talking about rinsing with citric acid or oxalic acid, what exactly do you mean by that? Is it straight? Or is it downstreamed, or pump sprayed, or 12V applied straight or mixed? I’m seeing my first really nasty wood fences and I want to start planning on how to take care things around here.

This is at my dad’s condo on the north side. And I’m seeing this stuff EVERYWHERE. So I’d like to prepare to clean wood while I’m building my trailer. I need to set up tanks and stuff still, so I might as well know everything I’ll need and do it all at once so I can clean all this stuff.

This is looking under my dad’s patio fence to his neighbors. My dad has bleached and scrubbed his patio a few times, so that’s why it doesn’t look black.

This is my dad’s fence on the back patio. All the fences here look like this or worse.

This is my dad’s patio. Better than his neighbors, but still, he just poured bleach on and then scrubbed it with a scrub broom. Never pressure washed.

This is over the fence into the neighbors patio… And a lot of them look like this. I really think I could have some opportunity around here.

You could come up with a fence patio package for the complex and make some bank if they look like that. Do your Dad’s and take lots of pics. Better yet use his neighbors for before pics, lol. Those fences easy-peasy other than it’s a shadow box which are PITA.


As @Racer said cleaning those fences and patios would be a piece of cake, staining on top of concrete depending on what you use is another story and shadowbox is yet another layer of grief. I am only telling you this so you know what you are in for so charge accordingly. If you use an oil based stain (it’s my go to is Wood Defender stains), know that it will drip for more than a little while and that is a significant challenge on top of concrete. It you use water based it is a PITA to get everything covered on shadowbox or a board on board fence but properly applied you will have very little to contend with getting it on concrete (my go to for water based is Sherwin Williams Super Deck). I stained over 115 fences last year so I have done a few of them. If you use oil based it will weep through knot holes and wick up around the edges and even more at the bottom. It’s really good for the fence BUT the neighbors may not be happy so particularly when doing shadowbox you need to talk to the neighbors because there are lots of edges etc. It can often get you another job because you are demonstrating the care you are taking with the everyone that can be affected by your work.


I will leave the wood to you guys…never had any desire to mess with it. I have a lot of wood at our place on the lake…it geta washed with the pressure necessary to clean it…never used and type cleaner…just blow the outside off and blow the water seal on…call it good as that is all that I will do.

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What would happen if a wood fence that wasn’t that old was cleaned with percarbonate and then pressure washed and no oxalic acid was added to brighten up and neutralize wood. Would a clear stain still adhere to wood fence or would the oxalic acid need to be done. Reason I ask is that after I used percarbonate and Pressure washed fence the color of fence looked really good and didn’t look as though it needed to be brighten anymore.

You would be ok. I only neutralized about every 50th deck when I did them and then I just used apple cider vinegar.

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