Sealing Antique Brown Granite
I have recently just had Antique Brown granite countertops installed in my kitchen.
Every time I (or the kids) leave a wet glass or other item sitting on the granite overnight, it leaves a water ring that does not wipe off.
It seems to lighten a bit over time but doesn't disappear entirely. The fabricator says the granite has been sealed, but I'm not so sure. And they say they will come and reseal it, but I'm not sure this will take care of the existing marks.
What is your opinion?
Well, Antique Brown granite is very dense and (typically) does not need sealing since it has a very low absorbency rate (will not stain easily). So, a couple things could be happening here.... One:
The slab you have is porous enough to absorb water left on the countertop for a few hours.
If this is the case, then you would see a ring/spot where the water absorbed that would take awhile to disappear (however long it takes for the water to evaporate from the stone). But eventually you would NOT see any ring. Two:
The stone has been sealed, but some granite sealer remains on the surface and is chemically reacting to the liquids (most likely acids) leaving a ring.
Often if you apply a sealer to a stone that is too dense to absorb it, you'll get a haze on the surface. And sometimes the sealer is (incorrectly) left on the surface to dry, but no haze develops.
Either way, there is sealer residue on the surface and many sealers will "etch" when in contact with acidic foods, drinks, cleaners, etc. Even high-alkaline substances can etch as well. If the rings definitely do NOT disappear
(i.e. you are not looking so hard you convince yourself
they are still there) then something strange is happening.
Antique Brown does not etch and should not be very absorbent, but every stone and slab can react differently and could be substance on the surface. You should perform
the lemon juice test
on your granite countertop to determine if it is porous, how fast it absorbs a spill. This will also tell you if the granite (or more likely) something on the surface (sealer residue) is etching.
Really, with this granite the lemon juice should sit there for 15-30 minutes or more even without darkening (absorbing into) the granite.If the test produces a dark spot
in 10 minutes or less, then your granite IS somewhat porous, hasn't been sealed (or not well) and needs sealing. If the test spot leaves a light-colored mark
noticeable after it has dried, then you have some issue with the sealer, which may need to be removed.
Request the installers to bring you a left over piece from your exact slab to test as well. Without seeing it, it's hard for me to give a definitive answer, so read the page about testing, etc. and do a little diagnosing.
Comparing tests of a leftover sample and your countertop should yield some an answers. If the unsealed sample happened to etch (light spot) with the lemon juice test, then that would be extremely odd for this granite.
doubt the solution is another application of granite sealer. My hunch
is that the sealer shouldn't have been applied in the first place and left-over surface residue is getting etched leaving the rings. If so,
you'll need to strip off the sealer (or whatever is on the tops) to eliminate the etching / glass-ring issue.
Complete details in the All About Sealing Granite & Marble e-book