Discoloured black granite

Some Robinson's pink grapefruit juice was split on our newly installed black granite from India. The granite has gone grey in colour where squash was split. Is there anything that we can do to restore the colour?

 

Dear Rebecca:

Read this:

 

BLACK ABSOLUTE GRANITE

 

Let's start by saying that when one mentions Black “Granite” one's talking about a huge variety of stones coming a little bit from all over the planet, each and every one of them not geological granite by a long shot, and each and every one of them with different characteristics. If that wasn't confusing enough, each and every one of them are processed with even if so slightly methods – which again can make a difference.

There used to be three possibilities to explain the problems that you are experiencing, which are here listed in order of probability (the first being the most probable):

 

1. The fabricator applied an impregnator/sealer to it believing that it's granite. No impregnator/sealer will ever be absorbed by black “granite” due to its inherent high-density; therefore it won't do the first thing about doing what's designed to do, which is prevent stains. (What you have are NOT stains, and no impregnator/sealer on the planet can prevent those.) Many a sealer turn out to be sensitive to acids; hence the “mysterious etching.” Not on the stone, rather on the sealer that had no business being there.
2. The slab had been “doctored” by the factory by applying some sort of black shoe shine in order to make it “blacker” and, therefore more “sellable.” After a while the “shoe shine” will begin etching as it gets eaten away by acidic liquids. The true color of the stone is dark gray.
3. It is one of those as-rare-as-a-white-fly “mutt” stones with some acid-sensitive minerals in it. In this case it is actually the stone that gets etched.

 

In the last couple of years there's been a change in the scenario above. Another possibility has entered the scene:

 

4. Certain manufacturers apply some sort of protective wax to the slabs. It is not actual “doctoring,” since there's no alteration to the color of the stone, but the result is the same as if the slab had been “doctored” with the “shoe-shine.”

 

Finally, case 3 above is not as rare as it used to be anymore. At least a couple of “Black Absolute Granites” allegedly from India and China entered the scene recently and are terrible “mutt” stones. Since they are cheap (to the importers) they push them like cra zy at full black absolute granite prices.

 

Having said all that, the remedy to the points 1, 2 and 4 is to remove whatever it is that's sitting on the stone surface, by either stripping it chemically by soaking it with a solution of water and phosphoric acid, or mechanically, by rubbing on the stone surface a polishing compound for marble (NOT for granite!) with a little bit of water.

Case 3 is terminal. It can be fixed professionally, of course, but it can't be prevented. Basically, the granite that's not granite is behaving like marble.

 

From a legal stand, cases 2 and 3 are full-fledged consumer fraud and could (and should) be prosecuted legally.”

 

Keeping in mind the severity of the discoloration and the fact that the stone comes from India, either case 2 or 3 are most likely, alas.

 

All things considered, black “granite” – which should be considered among the most enjoyable materials as a kitchen countertop – has made it out my own list of recommended stones.

Until the industry will not straighten its act up by becoming serious about the classification of all the different “granites” on the marketplace and dictate strict rules and guidelines about their characteristics and implied guarantees to the consumers, my position is going to be that from now on.

You can help! Actually, as a consumer of stone you're the best qualified to make things happen! Will you now please read and sign our Statement of Purpose by logging on at: http://www.marblecleaning.org/purpose.htm? By spreading the word about this valuable site among your friend & family and the stone trades' people you've been dealing you will be rendering everybody a valuable service!

Thank you.

Ciao and good luck,

Mauri zio Bertoli

 

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