Phenol Novolac Epoxies are a new breed of chemical resistant materials, able to withstand permanent immersion of many harsh solvents, fuels and oils. This Epoxy has much better bond strength than single component products, with strengths of up to 3000 PSI, and this higher strength reduces the need for a clinically clean surface, as the epoxy actually prefers to bond to a rough rusty surface. Our new phenol novolac is more thixotropic, which means it 'hangs' on the tank walls during the coating process. This gives a thicker overall coating. There is more volume of material in the kit to allow for this. We have found this 2-part epoxy product to be the best on the market. I believe you could make a gas tank out of cardboard and seal it with Caswell and it would work. Will seal small holes. We have sold thousands of these and done hundreds of motorcycle gas tanks with excellent results.