I gladly and humbly defer to Glenn on this one. I'm not a chemical
engineer, nor do I play one on TV, but I thought I had a pretty good
grasp on the basic chemical differences between the polyester family of
resins and the epoxies. It appears that the Hetron contains some
quantity of Bisphenol A, a major component of most laminating epoxies.
I could not locate the MSDS on the Ashland site - this would have been
instructive in deducing what perecentage of BPA is in the brew.

(For reference, West Systems all-purpose "105" epoxy resin is 50% BPA)

What puzzles me is the ability of MEKP to 'harden' the BPA, especially
if the BPA comprises more than a percent or two of the Hetron product.
My understanding is (was?) that a member of the Amine family is
required for the cross-linking (harding) of true 'epoxy' resins.

At any rate - as Glenn suggests - Hetron may not be a suitable resin
product for boatbuilding.

Mike Worrall
Los Angeles