2 Different Stains, Surfaces

[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...overs-C29.aspx
Claim - http://www.theruststore.com/Battery-...te-W57C36.aspx
MSDS - http://www.theruststore.com/msds/rus...r-concrete.doc

BUMP

1. 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%
   
   
2. 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