Cork and Rubber gaskets make excellent seals in oil and Transformer applications just to name two. ... If your cork gasket is bolted into place be sure and crisscross bolts as you tighten your flange. This will insure that equal pressure is applied around the flange.
How are cork gaskets made?
Cork Rubber Gaskets Cork Rubber material is a combination of first grade granulated cork and a synthetic rubber polymer. This gives the product the high resilience of rubber and the compressibility of cork. It is manufactured by combining the cork, glycerin-glue, and a rubber binder under heat and pressure.