Granite Facts: What is primary and secondary permeability?
Granite has poor primary permeability, which simply means that water and other fluids do not easily get past the surface. Almost no water at all can pass through the rock itself, so water can only be transmitted through cracks and fractures that result from the folding and faulting of the rock over time. Fractures create a secondary permeability. Although granite is unique, very durable, and scratch resistant, granite countertops need to be sealed periodically to keep liquids from getting past the surface. A properly sealed countertop will cause water to bead in droplets on the surface. When moisture spreads rapidly or begins absorbing, you know it is time to immediately reseal it.