What do I fill interior space with so metal does not oil can in and out?

thought H20 was water unkess they changed the formula.

 

Use plaster that is in the bag that you mix with water . Sets up real fast . DON'T use joining compound , costs too much and takes to long to set up ! Cement will work too . Cheap and solid .

 

We made some of those oil, gas, water cans up for a show-kustom project and we used old paint thinner cans. I don't know if that is what you are using, but we had no problems with oil canning in the metal. Use a palm sander on the cans, scotch-brite the tops, clean and prime, then paint. If you have some small dents they can be filled and palm sanded easily without putting a lot of force on the cans and warping them or oil canning. This doesn't answer your question on how to prevent the problem, but maybe you need to switch to another source for your cans?

JMHO

Doc

 

I checked out the expanding foam from the company I linked and it was way to expensive. It would have cost $190-300 depending on the hardness of the foam.

I like the fiberglass resin idea.

The question I have is will it stick to the tin plated can's? Will it pop off when the can is being sanded etc?

I will probably swish around the resin and then add small pieces of chopped mat. I may even open a small opening in the bottom of the cans and apply the mat.