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DICKEYBIRD
11-18-2009, 08:15 AM
Looks like I've stopped the leak in my fireplace so now I need to clean the whitish/greyish stains on my brick fireplace hearth. I've tried soap & water with a stiff brush but that didn't do much for it.

Can anybody suggest a good potion for removing it?

Doozer
11-18-2009, 08:35 AM
LimeAway or Muratic acid.
I said OR. Do not mix them.
Be careful with the acid.
--Doozer

tryp
11-18-2009, 08:38 AM
You will need an acid to dissolve the stains, it could be tricky bacause they are in the porous brick, try something mild like vinegar soaking and scrubing, step it up to glycolic acid if that doesn't work (CLR used to be glycolic check the label) or use muriatic.

If you go with the muriatic use rubber gloves, goggles and have plenty of ventilation and dilute it 10 to 1 with water.

dp
11-18-2009, 10:38 AM
There's a right way and a wrong way to dilute acid. Here's a quick tutorial for any who don't know the problems.

http://www.wikihow.com/Dilute-an-Acid

DICKEYBIRD
11-18-2009, 01:08 PM
Okay, I'll start with some vinegar & see what that does. We don' need no steenkin' muriatic acid in the house. (I hope!)

tryp
11-18-2009, 03:09 PM
I don't know why I didn't think of it earlier but slightly diluted phosphoric acid would be better as it isn't volatile. Getting phosphoric acid is more difficult though, hydroponics stores have it occasionally as pH down.

DICKEYBIRD
11-18-2009, 04:22 PM
I have some hydroflouric acid (auto wirewheel cleaner) and I may dilute it way down & try it.

tryp
11-18-2009, 06:38 PM
HF is not the acid to use here, volatile, corrosive to the brick and if it gets on you it goes through your skin and eats your bones, no kidding.

aboard_epsilon
11-18-2009, 07:09 PM
depends on what type of brick it is ...

with clay fired bricks youre safe with almost all cleaners ..

with concrete bricks ......you put acid on them ..and you desolve the cement away leaving sandy degraded surface.

all the best.markj

sch
11-18-2009, 07:15 PM
Ditto tryp: DO NOT use HF, the hazard to skin exposure is extreme, the
stuff melts right through skin and does really bad things inside tissue
before it gets to bone. Treating the resultant problem is even more
obnoxious, you can google up the problem.