Hi John,

Should also have an inside layer larger than the hole to be filled, if done at the same time the outer patch is applied you have a chemical as well as a mechanical patch, can't even come loose. Doing it only on the tapered outside hole only has the strength of the glue sticking to the tapered edges of the original glass, with enough flexing it is possible it could come loose.

Which is the problem fixing a canoe, you can usually see the inner layer of the patch, strong though.

Bill H.