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Soft Wash Wizard - Harrisburg, NC · Guest

Concrete Brightening with Oxalic Acid

Soft Wash Wizard - Harrisburg, NC · Guest

HELP - Does Oxalic Acid have a shelf life? Why did rust (IRON) bleed thur the two demo's we did but worked very nicely on another job?

I am looking for some input help to solve our current problem. So far 20 people have read my original post but no answers so far. For those who also clean concrete what are you using to brighten the concrete & your process?

gutterdog · Aug 30, 2011

I havent come across rust bleeding up on concrete? But I always brighten with oxalic acid, comes out nice!

Roof Cleaning Missouri 417-230-8103 · Guest

I use oxlic on concrete to brighten< I dont mix as strong as you. As far as i know , which I really dont, Oxlic does not weaken over time as long as it is in powder form,

I use oxlic on the concrete at the theatre, we have a roof that is rusty, (kinda gives it that rustic country look)and the down spouts drain on the concrete with gives it a rusty look< i spray and with in days it is coming back,

more than likely when their sprinklers come on its staining the concrete, I noticed it stains faster every time I clean it. tell them to seal the concrete or stop irrigating the concrete. sorry best I could come up with

al9226 · Premium Member Roof Cleaning Institute of America

gutterdog wrote:
I havent come across rust bleeding up on concrete? But I always brighten with oxalic acid, comes out nice!

After you apply the oxalic, do you rinse it? Do you do anything to neutralize it? Or do you just let it dry and go?

Sep 14, 2011

No need to rinse Al. Just leave it .

al9226 · Premium Member Roof Cleaning Institute of America

Roof Cleaning Palm Harbor FL 727 543 3276 wrote:
No need to rinse Al. Just leave it .

Thanks. Going to try it on my next job.

Doug R · Guest

If you dont neautilize it it the rust can come back.

Sep 17, 2011

Doug R wrote:
If you dont neautilize it it the rust can come back.

I have never rinsed/neautralized after applying and this has never been a problem.

However, the only times where it has come back hs been:

# 1 The customer doesn't adjust the sprinkler system to prevent it from hitting the concrete and or # 2 They do not have a system installed on their well pump which takes out 90+ % of the rust from the well water.

gutterdog · Sep 17, 2011

al9226 wrote:
gutterdog wrote:
I havent come across rust bleeding up on concrete? But I always brighten with oxalic acid, comes out nice!
After you apply the oxalic, do you rinse it? Do you do anything to neutralize it? Or do you just let it dry and go?

rinse concrete no. Wood yes. Also I tell people to not set anything down on the concrete till it dries. I think, but not sure, that that may cause a shadowing effect on the concrete.

Sep 17, 2011

gutterdog wrote:
al9226 wrote:
gutterdog wrote:
I havent come across rust bleeding up on concrete? But I always brighten with oxalic acid, comes out nice!
After you apply the oxalic, do you rinse it? Do you do anything to neutralize it? Or do you just let it dry and go?
rinse concrete no. Wood yes. Also I tell people to not set anything down on the concrete till it dries. I think, but not sure, that that may cause a shadowing effect on the concrete.

Oxalic acid is actually used on wood as a neutralizer and to brighten the wood.

gutterdog · Sep 17, 2011

Roof Cleaning Palm Harbor FL 727 543 3276 wrote:
gutterdog wrote:
al9226 wrote:
gutterdog wrote:
I havent come across rust bleeding up on concrete? But I always brighten with oxalic acid, comes out nice!
After you apply the oxalic, do you rinse it? Do you do anything to neutralize it? Or do you just let it dry and go?
rinse concrete no. Wood yes. Also I tell people to not set anything down on the concrete till it dries. I think, but not sure, that that may cause a shadowing effect on the concrete.
Oxalic acid is actually used on wood as a neutralizer and to brighten the wood.

Yea! If the homeowner is home I call them outside to watch the wood brighten! I like watching it too! But if you are going to seal it you must rinse the wood after brightening.

one time I was in a hurry and forgot to rinse, came back few days later to seal and It didnt get as dark as I was used to seeing it??? I think it was because I didnt rinse the acid off?

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