Testing and sealing absolute black tile

[AnnainOK]

Polished Absolute Bblack tile from Home Depot (product of India). Kitchen counter installation

How do I test to see if I need to seal? I'm on information overload.

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[doitright]

Hi Anna :)

You should not have to seal Black Absolute granite. Now you can TEST if it has been doctored though. Do you have any scraps?

[ceramictec]

yeah, you don't want to seal "Real" Black Absolute from South Africa.
it could enhance dark spots and turn out really bad.


I'm interested in the trick to finding out how to tell if you have a doctored black granite from John.
I have heard of other dark type granites being passed as absolute, but never ran into them.
probably the Chinese black granite made to look like Absolute Black.


*I'm even subscribing to this thread so I can learn about this.

[AnnainOK]

How do I test to see if it has been doctored, and what are the ramifications if it has been?

Thanks for the help!

[GeorgeT]

We have had calls from folks getting acid etching. Turns out there is a black basalt that is sold as Black Absolute. The basalt has a 9% calcite content...

A drop of vinegar on a scrap tile left for several minutes and wiped off will let you know if it is one of those stones.

Sometimes a Lacquer Thinner or Acetone scrub will bring up black if you use a white towel.....

[cx]

George, your people (StoneTech Professional) sent me an article a few years back on the problems with counterfeit Absolute.

I've managed to lose all my records, but maybe you could find that? I recall it being pretty informative.

[GeorgeT]

Hi cx -

We used to have it up on the website, but I just looked quick and didn't see it... I'll dig it up.....

[Stone Dude]

The most common test is the lemon test, but you can use vinegar or anything with a strong acidic content.

you guys have to understand there are two potential issues with the newer BA which are two completely different things.

1. etching- just because it etches, does not mean it is not Black Absolute. BA has been known to have a small amount of calcium binders, enough to show an etch, butnot severely.

many people misunderstand this as doctored. it is not, it is merely acid sensitive, which unfortunately seems to be the norm these days.

2. doctoring- doctored stone is when the factory uses a dye to achieve the rich black color on a stone that is naturally not so black. ,you can use acetone, MEK or just about any other solvent to check for doctoring. the most common give-away is rubbing the stone with a rag soaked in solvent and having the black color show on the rag.

NOW, both of the above will cause a lighter spot on the stone, but for two completely different reasons.

etch marks are always lighter than the stone, and removing color from a doctored stone will also result in a lighter mark, thus the confusion.

regardless of these issues, i have never seen anything penetrate BA. not to say its impossible to stain, its just very unlikely.


George, your previous post describes both of these issues.

[ceramictec]

I have heard of "oil rubbing" it and it actually makes it terrible looking.

[Trask]

Cameron nice to see you here:yo:

[ob1kanobee]

Take a clean white rag and apply some acetone to the surface of the granite. If any residue or black colour is observed on the top, do not accept it, it has been dyed.

http://www.stone-network.com/absolute_black_granite.html

[GeorgeT]

Black Absolute, as well as several other blacks, are essentially forms of volcanic glass. If you've ever broken a slab you'll have seen it does not break like anything else... oh man those sharp edges....

But staining these blacks? .. like Cameron said, its very unlikely.

and then there is another issue that can cause a white or lite haze; by using too much silicone solvent sealers on blacks. The sealers will spread out and cure ok but the film is susceptible to heat and acids ...
leaving a whitish spot that looks like an etch....

[AnnainOK]

The vinegar left an obvious change to the stone's coloration, turned at an angle or under the light, you're gonna know it was there.

No color came off when I applied the acetone.


Circling back 'round to sealing:


From reading other threads here, it would seem no sealer will prevent problems with etching...so I'm sunk in that regard?

[GeorgeT]

Anna -

Unfortunately, you will not be able to seal against the acid etch....
Penetrating sealers are just not going to stop that.

This might be a good time to determine what it will take to repolish this material. Etch marks will happen in the course of normal life....at a certain point you will no doubt want to repolish the etch marks.

[Stone Dude]

If youre not in love with the polished finish, a honed finish can be an option. granted the etch marks will still happed, but refinishing in the future will be drastically more cost effective.

[doitright]

Hi Anna :)

You said you can see a difference at an angle. Does the shine still exist? Has the color changed? It's not uncommon that the stone just needs to have the remainder of the sealer/coating removed, or it's one of the acid sensitive stones as mentioned above.

I personally don't recommend going the honed route.

[AnnainOK]

After reading the posts in this and a thread from last summer from a guy who installed the same tile, I decided to play it safe...I took all 24 boxes back to Home Depot! Why sit here and try to figure out how I would make it satisfactory?

Thanks to this forum, I've probably avoided a huge headache!

Anna