Fellas,
As stated I have a 4gpm 4,000 psi hot water unit. Mostly stick with commercial jobs. The other day I encountered 2 problems. I was washing a concrete slab with what appeared to be small red/bronze rust marks, it was either that or deep embedded red clay (I’m in mississippi) other thing was on a rental house a window unit had greyish white calcium stains running down it. No amount of pressure, heat or bleach cleaned this. Best ways to remove this stains?
These Stains*?
Pictures would help,
And use the search tool, and look up red clay, rust, and calcium.
Appreciate it. I’ll take some pics and get them uploaded as soon as I can.
Hydrochloric (muriatic) acid remove both rust and calcium stains. You can pick some up at a pool store. I think my store is two gallons for $20
HCl is the common ingredient in scale removers as well as ice machine cleaners, to remove the Calcium and Magnesium carbonate in water towers.
Oxalic also works well for rust, but it does a crud job on calcium stains.
Never use an acid full strength, always add acid to the water, not the other way around. If your mix of HCl is too strong it will bleach the concrete.
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You can try hydrofluoric acid, I use one marketed under the “Clearly Pink Pro” name, by Pressure Pro, I purchase it locally.
Muriatic may etch concrete
Hydrofluoric may etch ceramic
Wear gloves, mask, and boots, don’t let either touch your skin.
Thanks for the advice. I’ll try this out!
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