"For steel castings etc. where the mating surfaces do not flex, I would guess that a more spongy gasket might be best"
like a head gasket? ... or a thermostat housing gasket? ... or a trans side cover gasket?

gasket material depends on the "material" being contained as much as the mating surfaces - pressure, oil, grease, water, air
nowadays many gaskets can be replaced altogether w/ sealer, or 'liquid gasket maker'

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics