and many marbles will etch easily from acids (certain cleaners
Most granite countertops are so dense they don't need sealing, especially black. Leave a few water drops on your granite counter top. If you come back in 30 minutes and they are still there, then you don't need to seal it. Marble and other types of stone are more porous and usually need to be sealed. That being said etching is what causes most peoples problems. Calcium in some granites, and many marbles will etch easily from acids (certain cleaners, citrus fruits, etc). Sealing doesn't prevent etching. The acids react with the calcium in the stone. All this information is easily available if you search google. Its not just my opinion. Search granite, etching, etc. You will find this information on many websites. This product works well when you have a more porous counter top. Remember Rock Doctor is in the business to make money. They aren't going to tell you that most granite counter tops don't need to be sealed, nor will they tell you that sealing won't prevent etching. Sealing also won't prevent hard water stains around your sink if you leave the water on the counter top to dry around the sink routinely. The minerals will build up over time as the water evaporates.
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