Some countertops come pre-sealed, but if yours did not or you’re not sure don’t delay giving it the shield it needs. Improper cleaning, neglected spills, and other issues of everyday use could easily mar the surface otherwise. The proper penetrating sealer will soak into the granite, filling the porous gaps, to keep damage at bay. Water-based sealants are environmentally friendly, while solvent-based sealants may go deeper into the stone though this is arguably only important on polished granite. Check water- or solvent-based sealant labels for the active ingredient “fluorocarbon aliphatic resin.”