How do I fix my black granite countertop?

guest · 01-09-2007, 07:33 PM

I used the Politice method recommended on a web site to remove an Organic stain from an absolute Black granite countertop. The water stain is gone, however now the countertop is completely discolored where the politice was. How do I fix this?

Timm Sowders · 01-09-2007, 07:48 PM

Do you know if the stone was sealed before and what product was used? And maybe how many coats we applied?

Huligar · 01-09-2007, 07:51 PM

Timm, is this a job that you did.
Do you have any images of the area that you attempted to repair?

Timm Sowders · 01-09-2007, 08:01 PM

Sorry I was trying to say "how many coats were applied"

Huligar · 01-09-2007, 08:06 PM

I know, I just had to take that little stab at you.

Maurizio Bertoli · 01-10-2007, 07:46 AM

Dear Guest:
Ah, the perceived problem vs. the actual problem!...
Organic stain, huh...

1. You can't stain black absolute "granite"
2. There's no such an animal as a "water stain"
3. A stain - a true stain - is always darker than the stained material. If it's lighter, it's not a stain, but a "stain"; which means that's either a mark of corrosion (etching) generated by and acid, or a caustic mark (bleaching) generated by an alkaly. In both case they are actual surface damages - not stains, no matter what they look like.
There are no known exceptions to this rule
4. Since stone does not "bleach", your "water stain" was clearly an etch mark.
5. Poulticing and etch mark is like trying to poultice a scratch...

All that being said, we have now to determine what etched.
There are a few selections of black "granite" that contains certain minerals sensitive to acids. So this is a possibility, but the most common possibilities are:
1. An impregnating sealer was applied to your black "granite".
Black "granite" (gabbro, dolerite or anorthsite - never granite) is too dense a stone to absorb anything (that is why it doesn't stain), including the impregnator. And if you apply an impregnator to it anyway, some invisible film of the stuff may remain on the stone and react to acidic substances (lemon and orange juice, drinks, salad dressing, vinegar, tomato sauce, wrong cleaning solution, etc.) and show these weird "ghost water stains".
If you try to "poultice them out", you're actually damaging some more of the sealer that had no business being there in the first place. Hence, the more extensive discoloration (light color), which could be interpreted as a "larger water stain"!!

2. Your black "granite" is "black". What I mean by that is that it could have been doctored by the factory. A few selections of "black granite" (mostly from India and Zimbabwe) are not really black; just a dark gray when highly polished. Since nobody wants gray "granite", the manufacturers of the slabs doctor them by applying some sort of black shoe-shine onto them and sell them as "black absolute".
Typically the doctoring is sensitive to acids (see list above) and it get destroyed by it, thus showing the true color of the stone underneath. Once again, trying to poultice out that "stain" will only serve the purpose of removing some more of the doctoring agent.

The case of the "sealing anyway just in case" is the result of plain stone ignorance, but it can be rectified by removing all the sealer.
The doctoring can be removed, too, but you're never going to have a back stone. Just dark gray.

Just FYI, stone doctoring is a crime and infringes the consumer protection act big time.

Ciao and good luck,
Maurizio Bertoli