Is this really true? I think the partition coefficient is probably
comparable. The key to osmosis resistance is not the water barrier but
the lack of voids that can be filled with solutes...

Cheers MC

DSK wrote:

Are you talking about vinylester? It's still not as good a barrier to water
permeability as epoxy. Gelcoat is just a mix of polyester resin & wax. It's main
benefit to the boat is that it takes a gloss & it's cheap (although this
benefits the boatbuilder more than the owner)