Black Granite Tile

I read with interest on findstone forum, Maurizio Bertoli's description of why an absolute black granite tile would have lighter rings (So sorry for the lost of Maurizio). Basically, 1) sealant applied by fabicator, 2) doctored to add colorant 3) "mutt stone" sensitive to acid and 4) Wax applied by fabicator. He said 1,2,4 could be remedied by methylene chloride (paint stripper) to strip it -- in the case of 2) doctoring, you would have a dark grey stone. With that as background, MY case: I also saw just after installation the rings. I took a scrap piece of tile and added in separate spots lemon juice, vinegar, coffee, tea, oil and water. It was indeed the lemon juice (and to a lesser extent, vinegar) that lighten the surface. Nothing new versus the above...until I then coated the whole scrap with paint thinner (the thicker paste, not liquid, but still methylene chloride) and left it for 20 min... wiped off and no difference at all - the spots from the lemon were still there. I guess that could mean 3) mutt tile since anything else should have come off :( :( HOWEVER, I then just took lemon juice and wiped the entire scrap, leaving only a corner to compare. This "removed" the spot by making the whole suface just a BIT lighter (a touch browner if anything...) but you have to look at it 3 times closely to see that it is any different -- it is still shiny and black, just a little bit lighter. It looks fine to our taste. Finally I then took the 'lemon juice treated scrap' and put another drop of lemon juice on it and left it for an hour (to see if it would continue to lighten or etch or loose shine)... wiped-off and saw no difference - no new spot. SO...my thought is to go ahead and 'treat' the tile with lemon juice and take the slight color change as it is the rings that stick out, not the color change. Is this a crazy approach? Any ideas what is going on (do you think it is mutt tile, or should I try the Paint thinner again). I did purchase this from a "reputable" dealer - Louisville Tile -- I have not 'gone after them yet' on warranty until I know what is going on. Suggestions?? Thoughts?? Sorry I was so verbose above - I thought more background would be more helpful. PS. I'm a Chem Eng so I don't mind experimenting :) THANKS SO MUCH Forrest

A.Hello Forrest,

Your on the right track as true ab black wont etch.I would wait on the lemon juice approach until you can clarify the problem.Fred hueston sells a kit to determined if the stone been doctored.

You can find it at www.stoneandtilepros.com

Do you see what looks like shoe polish on the edge of the tiles.

Sometimes it could take longer than 20 minutes foe the mc to work. Possibly you bought a very diluted one.We hardly ever use them in the field anymore but if we did we would use a very strong mix like prosocos fast stripper.It will strip anything. It could be that you just have misapplied sealer issue thats causing the marks.Have you tryed acetone,if not do so. It may breakdown the sealer if that is the case.If you have a local stone refinishing pro closeby give them a call.He or she will be more than happy to have a look.If you cant find one check out the web site above or call me directly at 888-400-4302.

Stu Rosen