I want to remove the worn paint from our concrete patio, and someone suggested muriatic acid. How efffective is this stuff at removing old paint from concrete, and how toxic would the rinse water be to nearby bushes and shrubs? Thanks! --- John
it won't touch the paint, and will etch or remove the concrete.
i'd try a pressure washer first.
Just scrape off the loose paint with a stiff wire brush. Etch the exposed concrete with muriatic acid to help make the new paint adhere better.
Beware however, that the acid is very harmful to nearby plants, even when diluted. I was very careful to soak the surrounding ground with water both before and after application, and I used relatively little acid all together. Nonetheless I killed a holly bush beside the porch. You might want to sprinkle some lime or other base to offset the strength of the acid. Test the soil's ph once you are finished.
That said, I wouldn't use muriatic acid again unless the concrete was really slick and shiny like a new garage floor. Most existing outdoor concrete is plenty rough to hold paint.
Forget the acid. Use a powerwasher.
i cant remember as it was in first year college chemistry, but you eigher dont add water to the acid or the other way around or you will get an explosion???? dont use the acid if you dont know how to use it and have to ask on this newsgroup..... at least a power washer will pullup the paint and the most it will do is hit you in the face when it blast it off..
"Or the other way around"?? Don't broadcast warnings that are confused, mistaken, and wolf-crying.
(1) It's not an "explosion", but exothermic heating that can result in vigorous boiling.
(2) Generally, add acid to water, not "the other way around".
(3) With muriatic acid, neither (1) or (2) is a hazard, although there are other severe hazards. You must be thinking of, for example, sulfuric acid, which is quite exothermic when mixed with water. Muriatic is not.
Neither. Muriat = the pre-scientific, ancient term for chlorine, before chlorine was recognized. From the Latin, "muria", brine (muriat of soda, aka sodium chloride, table salt). Muriatic acid was an item of commerce before scientific nomenclature, and the name has persisted in commerce.
Thanks for the info.
Though adding acid to water is a good practice if you can't remember which acid is exothermic, HCl is not dangerous to add water to, this is because HCl is a gas, the liquid acid is HCl dissolved in water, IIRC 37% is about the max that will dissolve. As with all chemicals, including cleaning products, never mix things if you don't know what your doing.
-- "Shut up and keep diggen" Jerry
"Synonyms: muriatic acid, chlorohydric acid, dilute hydrochloric acid, dilute HCL"
jim ___ Have a home upkeep question? Try my help page. It's sort of an alt.home.repair FAQ.
Even when HCl is diluted, it is still called a "strong acid" because it is so reactive; ie, it readily gives up hydrogen ions. Dangerous stuff to store around the house. Goggles, rubber gloves, proper ventilation and caution are important.
In alt.home.repair on Mon, 30 Jun 2003 21:26:50 -0500 jim posted:
It's pretty easy to remember the rule if you understand the rule. At least I think this is why it is dangerous to add water to acid. If you add water to acid, at the start the concentration of the acid is still very high, almost as high as it was, and now it has this intruder, to interact with.
If you add acid to water, where there is a mixture, it is almost entirely water.
When I hadn't thought of a reason, it seemed like the rule should be the other way around, because pouring water seemed safer than lifting a beaker of acid, moving it around, and pouring, maybe spilling, it.
Meirman
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muriatic acid wont remove paint, will damage shrubs and plants and your lungs from fumes. It will clean dirt off concrete, use a respirator stay upwind, cover plants with plastic, leave on for 5 minutes and brush with a plastic brush on a pole and rinse. No it will Not remove paint and No it will not be a problem diluting it. Try paint remover first
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