My Black Granite Counter Top is Fading 8/31/2011 11:53:00 AM 
Your phone rings and the lady on the other end is yelling at you complaining about her black granite countertop that you installed for her about a month ago. She tells you that there are gray faded spot appearing all over it. Your first thought is she is using the wrong cleaner on it. She assures you that she is only using the cleaner you recommended. You tell her you will be out to look at it and see what the problem is.
This scenario occurs almost every day in the stone industry and is becoming a serious problem. The most common complaints seem to be on Absolute Black, Black Galaxy, Zimbabwe Black and a few others. I have heard many fabricators try to blame the fading on the misuse of cleaning chemicals, acids, etc. While one should not use inappropriate chemicals on granite surfaces, this is not the reason for the increase in black granite fading.
Black granite should not fade. Black granite imported from Asia and India is sometimes doctored with dyes and oils to darken the surface. Dyes can include homemade blends such as charcoal and linseed oil. Prepackaged color enhancers are also used to darken granite. The fading is nothing more than the dyes and oils being removed. Of course the wrong chemical will take the dye out faster, but I have seen many of these dyes removed using simply water and a mild cleaner.
Dyes are not the only reason for fading. I am also seeing black granites that are etching from acids. This is the result of calcium binders that are now being found in certain granites. Calcium is the mineral found in marble and limestone and is very susceptible to acid etching. Some black granites are being quarried that contain some calcium and as a result will etch when exposed to acidic liquids and foods such as lemon, fruit juices, etc.
How to Tell if Granite is Dyed or contains Calcium binders
Before purchasing a granite slab perform the following test to find out if it has been doctored or contains calcium binders.
Take a clean white rag and apply some acetone to the surface of the granite. If any residue or black color is observed on the top, do not accept it, it has been dyed. If you get no dye from the acetone then take some MEK(Methyl Ethyl Ketone) and apply to a different part of the slab. If you get any color transfer the stone is dyed. These chemicals can be purchased at most home improvement or paint supply stores. Some dyes are also resistant to these chemicals as well. There is a test kit available that will not only test for dyes but will also test for calcium binders as well as resined stoned. These kits are available from several stone tool suppliers such as Braxton Bragg(braxtonbragg.com) and Stone Care Central(stonecarecentral.com).
Now What can you do
The reason granite is dyed is that its natural color is gray and it doesn’t have that deep black color that some black granites have. For this reason many factors use deceptive methods to doctor these slabs pawning them off as deep black granites.
The only solution is to re dye the granite. But keep in mind that these dyes are only temporary and the fading may return. Dyes can be purchased from Tenax (tenaxusa.com). If the granite contains calcium binders it may be able to be repaired with traditional polishing methods but it will still continue to etch if exposed to acid liquids and foods.
In addition to dying many types of granite are also injected with resins, which can also darken granite.
