Absolute Black - Faded by Poultice

[jwnorth]

I recently went to a customer and removed a stain from some absolute black granite.  I used a commercially available poultice (Mangia Macchia) which did remove the stain, however it has lightened the color of the granite in the area where it was applied (I know this for sure since I taped off the area where I applied the poultice and a line is now visible on the surface of the granite, one side of which is the normal black color and the other side is "gray").  I have since applied several coats of black wax and buffed with steel wool and also applied a pourable resin/wax product that was also buffed out with steel wool.  None of these worked.

Does anyone have any advice on how to restore the original dark color to this affected area?

[Mark D.]

What is the pourable "resin/wax product" that you used?
It IS resin based?
Did you put it on over the wax?
(Yes, I know that is a stupid question, but I have to ask.

Mark

[Stone Dude]

some black granites are treated with a stain of some sorts at the factory. most of these come from china and are considered inferior stone. unfortunately, if this is the case, theres pretty much nothing you can do about it, and the stone will have to be replaced. hopefully this is not the case. would try polishing it with a buff pad or some sort of potea granite polishing compound to see if it helps.

[Mark D.]

If it is the Chinese Black that is problematic the Calcium content is way too high and the stone will turn white merely by leaving a glass on it for an extended period of time.
You can stain it with Uniblack from Tenax and then use a black wax, but the problem will happen again if it is that stone.

If it is not that stone but you have removed the stain you can restain it. By the way, black absolute is NOT granite. It is usually Basalt and therein lies the rub.

Glad to be of service,
Mark

[Stone Dude]

the problem is the process they use at the factory to achieve the black color, it cannot be duplicated in your shop. at least i havent heard of anyone being able to fix this issue. and if its not granite, but basalt, then the calcium content cant be too high, because there is none. he hasnt even specified whether or not is polished or honed.

jwnorth can you please post some pics. this is hard to diagnose over the internet.

[jwnorth]

First off, thanks so much for the information to date.  All extremely useful and very reassuring to know that there are so many helpful folk out there.

The material in question is polished and none of the shine has gone in the affected area.  The discoloration is very slight and only really noticeable because there is a straight line between the affected and unaffected areas (I used tape to mask off the area where I didn't apply the poultice).  Once I used the black wax (Black Pamir) I used a product that is new to us; the text on the blue can reads EXTRA LUX Vernice autolucidente.  I applied a thin coat of that to the granite, left it overnight and again removed it with steel wool.  I've subsequently resealed the surface of the granite.

Unfortunately I don't have any photos of the surface; I'm not even sure the difference in color would show up in a photograph.  As I mentioned the difference in color is very slight.  If the regular black color of the granite is baselined as 100%, I'd rate the affected area as a 98%.

I've seen the Uniblack product advertised but have never tried it.  Is it a stain?  If so should I be concerned about darkening the area too much?

Jonathan

[Mark D.]

Jonathan,
It is a stain and then a black wax that Tenax developed to combat the Chinese Black. We have never sold it but can get it for you if you like.
I am unfamiliar with EXTRA LUX Vernice autolucidente. Who makes it? IS it resin based or water based? Did you put the wax on over it? If you did you may have a problem with the wax not spreading properly over it.

Mark

[Stone Dude]

you say its polished, and the problem area still has its polish?? you might want to try a nylon scrub brush and nuetral cleaner. i have had several encounters with fine powders getting embedded in the grains of the stone giving the impression that it had discolored. each time i scrubbed the S___ out of it and it was fine. the wax, towels, and other cleaners wont get it out unless you actually get to the deposits. it sounds like your problem is a lot less of a headache than originally thought.

[jwnorth]

Cameron

I hope you're right; that would help make my weekend get off to a good start if all I have to do is get aggressive with a nylon brush.  What type of neutral cleaner would you recommend?

Jonathan

[Stone Dude]

 go to the cleaning section in home depot, and buy a gallon of ZEP neutral floor cleaner. its cheap and works well, and you can clean any stone or porcelain without hurting it.