Aha! The secret ingredient... well spotted

Its silicone rubber, good they say to 260 Deg C. The canister runs really hot!

My buddy Scott suggested it as he had a can in his giant Extra that was burning the surrounding wood even with an air gap.

I got it at a kitchen specialty store where it's sold as cookie sheet

$10 for a 600mm x 300mm (24" x 12") sheet. (@ A1)

Works like a charm.

Goose