Sealing Black Granite

by Sharon Wiest
(Orem, Utah)

QUESTION: I have black galaxy on my kitchen island where every type of food gets on it. It has etching marks in the areas where food is put on it the most. My home is three years old and I have not sealed anything yet. I think it had sealer put on it after installation.

My counters have a beautiful gloss to them. The marks are underneath the gloss. Can you tell me what I can do for the black galaxy? Can I do damage to any of my granite surfaces by using a sealer on them? I am afraid to do any of it, in case I ruin them.

ANSWER: True Black Galaxy is nearly impossible to stain, etch or damage in any way and is one of the best stones for the kitchen.

It is very dense, so nothing gets absorbed into the stone. Thus, it doesn't need to be sealed.

In fact, true Black Galaxy can't be sealed since the impregnator/sealer will not absorb into the pores of the stone.... and don't do it for good measure.

You won't necessarily "damage" the granite, but applying sealer to Black Galaxy usually results in a milky sheen dried on the top. That's the sealer that didn't absorb and now needs to be removed with nasty chemicals and probably a professional.

Now to your "etching" problem....

Unfortunately, in recent years some quarries have been "doctoring" their Black Galaxy.

Why? Well, the particular Black Galaxy that they are mining from the quarry is a good stone, but it does not get "black" with polishing (machine polishing is what brings out the color in stone). So, they have been applying some sort of coloring agent prior to polishing.

Many problems have been arising with substances reacting with the artificial coloring (not the stone itself) applied to these doctored slabs.

Without actually seeing your countertop I can't be absolutely certain, but my best guess and the most probable answer is that you have a "doctored" slab and the coloring agent is what is etching... not the stone.

If it were true Black Galaxy, it would not etch and you simply would not have this problem with normal food prep.

I'm sorry to say that there is no remedy except to have the original installers replace the slab. This is an issue of consumer fraud and you should definitely contact them about it.

It may be possible to have the coloring removed, by re-surfacing the stone, but that is a HUGE mess, expensive and most likely it would not be black after polishing.

Again, sealing won't do a thing to correct or protect against this issue.

Sharon, you had a couple other questions that I created separate links for. Please see "Permanent Sealer" and "Sealing Travertine Shower" links.

Ryan