Is there ACID BURN on this Pa. bluestone?

by Cindy
(Seattle, WA)

/Users/evans/Pictures/iPhoto Library/Modified/2010/Apr 25, 2010/IMG_7695_2.JPG

A PHOTO should be here! If not, I'll try sending photo again.

A month ago I sent question here about efflorescence on new mortar set flagstone. We then called Prosoco but they couldn't help.

(The contractor did mortar set on old 20x20' 1960's cement patio. Done in the rain and not cleaned at all until totally finished.

Then the contractor used muriatic acid 3 times at full strength. Contractor then tried 600 Detergent and later small amount of Ef-fortless. Still has drips, blobs, splashes, boot prints, and milky look. Some pieces seem darker, lots look bleached out.

--DID the REPEATED ACID TREATMENTS "burn" the Pa. bluestone?
--What are long term implications if burned?
-- WHAT DO YOU RECOMMEND TO IMPROVE surface? Maybe sealer?

(The blue tape shows a different problem. The acid washed out the mortar between stones so it is now sandy, deep grooves, holes, and water collects in spaces.)

We appreciate you help. We bought your video--after the problem happened.


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flaking is not always bad
by: JC

hi. my contractor burned my stone as well. however, i removed the sealer and now the stones are flaking. all the thin burned layers are flaking off!! a few more weeks of this and i will have the natural color back. will then re seal. good luck!

acid is probably the problem
by: David

Dear Cindy,

The picture didn't come through, but it is very possible that the acid burned the stone.

My dad never uses acid on stone. He does with bricks, but then he hoses it immediately with water because it could burn the brick. I've used acid a few times with him and it is very, very strong stuff. It even burns up the brush quickly.

Even now with brick, he uses Prosoco products because he's afraid of burning.

We haven't worked with much Pennsylvania Flagstone, so I'm not sure what a burn would look like.

I'm sorry Prosoco didn't have a product to help you.

A sealer wouldn't do anything if the stone is burned and unfortunately, if the stone is burned there's nothing that you can do, but tear the stone up.

My dad always worried about that when he washed. He said, "Burning means replacing."

You might try to sand blast. If you do, try it on a small area of stone to see what the results are.

I'm sorry I can't give you better news. That's all that I know for your situation. Ask the stoneyard where you got the stone. My dad often talks to the stoneyards for new tips and ideas. Hopefully they might have some better solutions for you.

Great luck with your project!!


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