Re: sealing granite
Granites vary in their porosity, plus each mineral in the granite has different strengths, plus there are sometimes beautiful cracks and voids that were re-mineralized during the millennia with different minerals that react to acids and caustic cleaners differently than than the main body of the stone.
When you go to the stone yard, or when your counters are installed, feel around the edges. Look at the underside. Many, many granites are coated with a resin at the quarry or importer. You can see it and feel it. The fancier the stone, the more likely this has happened for logistical reasons - it keeps the slab intact. It’s a good thing. You don’t need to seal, like ever.
Sorry, my inner geologist got away from me.