Originally Posted by crxmanpat
It's not the paint that eats the foam, it's the propellant. Keeping the can at least 12" away from the foam allows the propellant to evaporate before reaching the foam in sufficient quantities to melt it.
Actually, it's the solvent in the paint that melts the foam, but the rest is true. The propellant is typically a hydrocarbon, like butane or propane. The solvents are foam-nasty things like acetone and toluene, and MOSTLY evaporate before hitting the foam. If you're patient, you can spray as you describe with most enamels. I think the solvent in Testors is kinder to foam though anyways.