Those who aren't familiar with marble and granite are often surprised to learn that cleaning these materials is a bit tricky. After all, they're both stone! Isn't stone usually nearly invincible?

In reality, stone can only be thought of as "nearly invincible" if you don't care what it looks like. It's true that you could drive on a sufficiently-thick slab of granite, and it probably wouldn't shatter. However, such treatment will make the visible surface of the stone ugly, and that is not acceptable in most situations. A surprising amount of care is actually needed if you want your stone to remain attractive.

One of the reasons that marble and granite cleaning requires caution is that it is usually sold with a high-gloss finish. The gloss isn't from the stone itself, but instead, it comes from a chemical finish that is applied once the rock has been made smooth. This finish is subject to deterioration from harsh cleansers as well as from acids that get on it. Even the level of acid in a cola spill can eat through this finish if it is not wiped up very promptly.

With granite in particular, porosity is another issue. If a spill does manage to get through the applied finish, it will soak into granite. After this happens, it won't come out with regular cleaning. Instead, the stain has to be ground or polished off.

Marble and granite polishing techniques depend on the condition of the finish. If the finish is intact, polishing with soft cloth or a soft buffer is often enough. However, if a stain is down in the stone itself, marble and granite polishing may have to be more abrasive. In that case, the stone will have to be refinished once this is done.