Anybody here ever come across any material to make a gas can cap gasket that actually seals AND doesn't grow to double size after contacting gas?
Try cork or leather;
Cut a piece of cardboard from a tablet back or shoe box.
Cardboard, good idea. You might soak it in paraffin to protect it from the gas.
Leather works great.
TO TED AND ROBERT: I needed a gasket and this will be a good way to try.
A local auto supply should have cork for cutting your own gaskets. Why pay for shipping that costs more than the product?
I keep my old worn-out boots to salvage the leather uppers for gasket making.
There ya go, Dave. I do the same. That way there's no cost for material or shipping.
How about an O-ring?
Are you talking about a metal gas can? Or a plastic gas "can"?
I've used the top from a Chinese soup container. If you don't like Chinese takeout you can get a 1/4 pound of potato salad.