By Frederick M. Hueston
I have received numerous calls lately concerning the fading of black granite counter tops.
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 mis use of cleaning chemicals, acids etc. While one should not use inapropriate chemicals on granite surfaces, this is not the reason for the increase in black granite fading.
Why does black granite fade?
The answer is, 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 home made blends such as charcoal and linseed oil. Pre packaged 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.
Here we see fading of a dyed Black Absolute Slab
This picture was taken in India showing a worker applying dye to the granite.
Dye dripping down the sides of black granite
Testing for Dyed Granite
Before purchasing a granite slab perform the following test to find out if it has been doctored.
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.
Can Dyed Granite Be Repaired?
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.
Unfortunately, there is no fix. Other than to dye the granite again.
In addition to dying many types of granite are also injected with resins, which can also darken granite. For further information on the resining process see my article titled Resin Slabs, The Good, The Bad and The Ugly at www.stoneworld.com.