# Oxalic Acid Question



## slinger58

As much as I don't want to, I going to stain a deck next week. As part of the prep, I'm going to use some F-8 to clean/brighten the wood. My question is is the oxalic acid damaging to other surfaces such as plants, painted surfaces, unpainted metal, etc.?


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## Jmayspaint

It can etch metal, but overall it's pretty easy to work with. I've used it a lot, and never seen any damage to plants or painted surfaces provided standard precautions are taken. Pre rinsing, etc.. 

Troy probably has a better answer. 


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## slinger58

Jmayspaint said:


> It can etch metal, but overall it's pretty easy to work with. I've used it a lot, and never seen any damage to plants or painted surfaces provided standard precautions are taken. Pre rinsing, etc..
> 
> Troy probably has a better answer.
> 
> 
> Sent from my iPhone using Tapatalk




Thanks J. From what I gleaned in my brief google search, it's derived from plants and has a wide variety of uses.


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## Dave Mac

good to remove rust also, just keep every thing wet


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## slinger58

It occurred to me that maybe I've become too dependent on the internet for answers to questions like I posed in this thread. So this morning I mixed up a one gallon batch of F-8 and put some on some painted surfaces. Seemingly no effect . 
Then I took a chrome plated wrench and submerged it about halfway up in the oxalic mix for 15 minutes. Again, no effect. 

And as Troy suggested in another thread, I applied it direct instead of downstreaming. It does work better that way.


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## slinger58

So I'm prepping another deck for stain. PT pine about 12 months old, never had any coating on it. I applied the oxalic direct with pump up sprayer. Mixed 4 oz. F-8 per gallon of water and tried to give it 5-10 minutes dwell time. I say tried because direct sun and 80+ degrees dries it pretty quick. Then pressure wash with soft wash tip.

As the pic shows, the results are kind of spotty. The gray of the weathering is gone, but a lot of areas are still showing silver after it dries. Any ideas about why it's less effective in some places than others and what can be done to correct this?

Does Oxalic have short shelf life (it's probably 2 year old stuff)?

Now if I can get this pic to post.










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