2 Different Stains, Surfaces

[polyvue]

I have two different stains that I need help with. The first stain is less than a day old; it is of the most concern. The second stain, on my concrete deck, is three years old.

1) I spilled ~20% Silver Nitrate (Taylor reagent R-0718) on my white formica kitchen counter top. Trying to remove it by wiping it up quickly with a wet paper towel, then with dishwashing liquid and water, accomplished nothing. In truth, the first attempt wasn't entirely pointless -- it increased the stain's footprint on the counter. Ugh!

2) Before I understood that it's a bad idea to leave open or recently used containers of pool chemicals on the pool deck (especially if you plan to kick it with your foot while netting the pool one month after the concrete is poured) I did the unthinkable and then compounded the problem by doing nothing for almost an hour. (Of course, I realize now I could have likely erased this embarrassment by immediately hosing it off with water.) But my inaction caused a couple of ugly stains (7-8" long X 4-5" wide) that are quite noticable right in front of the entrance to the pool. The offending chemical came from an open plastic container of muriatic acid 31.45% (HCI 20° Baumé); washing and scrubbing an hour later had no effect and they've not faded with time. Is there any remedy for embedded acid stains on poured concrete (broom finish) that doesn't involve replacing the concrete? The deck concrete was colorized upon application to effect a light tan or sand tone, but the orange stains stand out.

All responses welcome. Thank you.

[polyvue]

Problem: Muriatic Acid stain on Concrete pool deck

I came across a product called Concrete Rust Remover (via a Google advertisement, Ben may be interested to know, displayed on this very page). The MSDS states that it contains sodium hydrosulfite.

Does anyone know if sodium hydrosulfite would be effective (or harmful) in removing the muriatic acid stains laid down more than 2 years ago on my concrete deck? The company's website claims that it can be used to eliminate the orange stains caused by car battery acid.

Product - http://www.theruststore.com/Concrete-Rust-Removers-C29.aspx
Claim - http://www.theruststore.com/Battery-Acid-Stains-on-Concrete-W57C36.aspx
MSDS - http://www.theruststore.com/msds/rust-remover-for-concrete.doc

[AnnaK]

Argh!

I spent two years of my life with black stains on my hands from silver nitrate which had oxidized.

For the formica you can try Jeweller's Rouge, a fine red powder used to remove silver oxide. It may dull the formica surface but would that be worse than the present stain?

Can't help with the concrete, sorry.

[polyvue]

Argh!

I spent two years of my life with black stains on my hands from silver nitrate which had oxidized.

For the formica you can try Jeweller's Rouge, a fine red powder used to remove silver oxide. It may dull the formica surface but would that be worse than the present stain?

Can't help with the concrete, sorry.

I want to thank you for suggesting Jeweler's Rouge because it led me to experiment by applying regular silver polish (Wright's Silver Cream) to the silver nitrate stains. This worked well, removing 90% or more of the visible stain on first application. The product MSDS lists only two components: microcrystalline silica and sodium carbonate [soda ash!]

There are probably other ways to lift silver nitrate stains from hard surfaces. I didn't think to try a powdered cleanser, such as Bon Ami, before the experiment, so am unable to judge its effectiveness; nor was iron oxide paste (Jeweller's Rouge) tried. The sodium hypochlorite, surfactants and carboxylic acids in the dishwashing liquid, bleach and spray cleaner had no obvious effect, but constituent strength (household concentrations) and duration of contact (< 1 min.) preclude negative inference.

I’m just very glad it worked. Onward now to resolving (dissolving?) acid-stained concrete….

[AnnaK]

I'm glad it was mostly successful and hope you'll find something to deal with the HCl stain as well.

[polyvue]

Problem: Muriatic Acid stain on Concrete pool deck

I came across a product called Concrete Rust Remover (via a Google advertisement, Ben may be interested to know, displayed on this very page). The MSDS states that it contains sodium hydrosulfite.

Does anyone know if sodium hydrosulfite would be effective (or harmful) in removing the muriatic acid stains laid down more than 2 years ago on my concrete deck? The company's website claims that it can be used to eliminate the orange stains caused by car battery acid.

Product - http://www.theruststore.com/Concrete-Rust-Removers-C29.aspx
Claim - http://www.theruststore.com/Battery-Acid-Stains-on-Concrete-W57C36.aspx
MSDS - http://www.theruststore.com/msds/rust-remover-for-concrete.doc
BUMP


Is there any remedy for embedded acid stains* on poured concrete that doesn't involve replacing the concrete? The deck concrete is a light tan or sand color, broom finish. The stains are orange/rust. Can they be sanded off? Bleached out? Is there another chemical treatment I should consider?

*Caused by muriatic acid 31.45%


Would applying sodium hydrosulfite hurt or help?



All responses including wild conjecture accepted.

[chem geek]

The sodium hydrosulfite (aka sodium dithionite) is a reducing agent so perhaps the acid stains are a form of iron oxide rust from some iron ore particles in the concrete, possibly from the coloring of that stone (maybe from iron sulfate). Basically, it sounds very much like stain removal from plaster which is really concrete (i.e. it's not really Plaster of Paris which is calcium sulfate -- pool plaster is really concrete which is Portland Cement with aggregate that is finer than in normal concrete).

The sodium hydrosulfite is a particularly strong reducing agent in basic/alkaline conditions (i.e. at high pH), though the product itself is acidic (according to the MSDS).

I don't see a problem using it, but of course you can try some on a small area first just in case.

[polyvue]

Richard

I haven't tried this product yet but I wanted to thank you for your response.

Will report back on its effectiveness once the deed is done.

GReg

:)