I had my kitchen countertop replaced with granite. Granite was installed over 5/8" plywood. The new sink is 22"X33" top mount cast iron. The installer set the sink on the granite but did not seal the perimeter. He said it needs a different sealant when I ask him to use his white silicon. He said to check Home Depot what kind I need. Is there anything wrong using silicon? I know it will spread beyond the sides of the sink before being cleaned, specially now that I can no longer lift the sink. Will it damage or stain the granite? How about Plumber's putty?