I didn't mean to imply that there was anything particularly wrong with cork as a gasket material. It's an old time choice that has been used successfully for many years in such service. I indicated that I made mine out of a non-cork material - actually Victolex
. I prefer that over cork because I think it is less brittle and easier to work with if you are cutting your own out of sheet material. I also think it is easier to remove at some later time without tearing, like cork sometimes has a tendency to do, especially if a gasket cement had been used.