I have found the nasty silicone. It is called Through the Roof.Purchased at a Tru Value hardware.It will seal anything and quickly. So be carefull. Acetone is the only thing that will take it off and even then its tough. Even before it dries. Besides sealing anything you want to, it also acts as an adhesive. Dont get it on your hands and then lean against the fence post. You may be there when the fence is rotted. Also, for hard to get at screws, where you cant get your hands into a tight place, just put a small dab, pinhead size on the blade of the screwdriver, wait a few seconds, and the screw will stay in place until you get it started. Good stuff,but nasty.Martin