Poultice marks on granite

Geoff · 02-13-2007, 08:29 AM

help! I have just used a poultice to remove wine stains in a dark grey granite table top. Tho poultice was made up of diotemacious earth and 20% hydrogen peroxide. After removing the poultice, the stains seem to have gone but there is now a mark where the poultice was. The mark is very obvious, much lighter than the surrounding stone. This area is now also rough to the touch. There is no discernable difference to the finish, because if you look at it with the sunlight reflecting on it, it looks no different. There is also a darker area where the plastic covering was over the poultice. Any help/advice would be appreciated.

glenn k · 02-13-2007, 09:50 AM

geoff,

do you have any pics? any knowing the name of the granite would help too.

glenn k

Fred Hueston · 02-13-2007, 11:29 AM

Try placing some dry DE on the area and let it sit overnight..The dark area is moisture. You should be able to remove the light area with some Acetone,,unless the grainte is dyed.

Huligar · 02-13-2007, 11:59 AM

Geoff, are you sure it is a granite?

Geoff · 02-13-2007, 06:07 PM

Thanks for your replys guys. I am an independant applicator here in Canberra Australia and there aren't too many of us so its good to have a vehicle to toss things around and get advice. Firstly, no Im not sure it is true granite. I am only going by what the owner tells me. Im going back there today so I will get some more info in that regard then. Assuming its not, then it would most likely be bluestone (basalt)? Would the poultice I have used be a problem on this stone?
Fred, I will try some acetone on it today, but I dont understand why or what it may do? If the stone is dyed (which I could understand causing the problem) what can I do? There are actually two tables that are in the courtyard of a wedding reception centre, so its important that they look good.

Huligar · 02-13-2007, 06:19 PM

Geoff, do not forget to take your camera. The reason I ask if it is granite, is because it sounds to me like you are describing and etch mark and moisture in the stone.

Geoff · 02-13-2007, 06:22 PM

I will take the camera, but to be honest, I have just spent the last 10 or 15 minutes trying to figure out how to add a photo. I still haven't figured it out yet!

Huligar · 02-13-2007, 07:13 PM

No sweat Geoff, go to http://www.nsraweb.com/gallery/ and upload you images, copy the link that it provides and paste it in your post.

StoneBuddy · 02-13-2007, 11:46 PM

If the stone is dyed, the acetone should remove the doctoring in an unaffected spot. If you get color on your rag, it's coming from the stone, you have doctoring. But I don't think hydrogen peroxide 20% is enough to remove doctoring is it Fred?

Can you scratch the stone with your pocketknife(assuming you carry one, don't we all?)? If you can scratch it easily that means the stone is softer than your knife, and most likely not a "granite."

Geoff · 02-14-2007, 09:02 AM

Hey guys, you are all champions! I cant tell you how much I appreciate you taking your time to offer your suggestions and advice. After several years helping a mate who was sealing slate and terracotta floors, I started my own business called Seal of Approval full time 4 years ago. I have done training with DryTreat and Aquamix and have othewise learnt as I went along. There are not too many of us here to bounce things off, so again, thank you.
I went back to the job today and took the pictures that I hope have come up okay. I tried the Acetone but did nothing, to either the damaged area or the original stone. there was no blackness or colour on the rag either. A closer inspection reveals pitting of the surface where the poultice was. Its not an etching of the entire area like marble etc will etch. The owner of the Centre cant tell me where the stone is from or what it is called. He bought the tables as granite tables.
Boy this is fun! huh?

Marble

MARBLE: CHARACTERISTICS

This standard includes general information on the characteristics
and common uses of marble and identifies typical problems
associated with the material.

INTRODUCTION

Marble is an extremely hard, metamorphic stone composed of calcite
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of marble. For this reason, it is always important to determine
the exact type of pollutants causing marble deterioration.

Marble itself can be of two types, one composed of calcite and the
other of dolomite. Dolomitic marble is much more resistant to acid
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