When it rains, I notice a dark stain running around the perimeter of each granite tile on my back porch. This outline doesn’t seem to ever go away. What’s causing this and can it be cured?

This shadow or halo is a sign of moisture in the granite. When the stone gets wet, it turns dark; the granite then dries from the center out, leaving a moisture shadow which has the appearance of a stain. To eliminate this shadow, the granite will have to be dried completely, followed by the application of a good silicone impregnator.

TIP To speed the drying you can place several fans on the granite. Be sure it has dried throughly before applying the sealer.