If my marble counter is polished with a high-gloss finish, does it still need sealing?
Absolutely. Regardless of the finish, marble and other natural stones are porous; which means they are susceptible to dirt and moisture penetrating the surface. Over time, dirt and moisture that has seeped into the stone can create stains or compromise the marble’s integrity.
The sealer you use must have particles small enough to penetrate the surface and stop dirt and moisture from seeping into the tiny recesses within the stone. It’s best to use a penetrative product like Tuff Duck Granite, Grout, and Marble Sealer to protect your counter from staining and etching while maintaining its high-gloss finish. We used it on some marble tiles at home about two years ago and we haven’t had any complaints about its effectiveness. Our tiles still look like they were laid down a few days ago.