[Downriver Tackle]

I've been formulating paint and coatings for about 15 years. I can guarantee you that ployester flakes are fine. I've used automotive effect pigments cast on polyester films in 2 component epoxies and urethanes, and never seen a reaction. Theoretically and chemically, it's almost impossible.

Honestly, from your description of the heat generated, it wasn't the amount you mixed either. Though, I probably would mix less, as recommended. My theory is that the part A wasn't mixed thoroughly by the manufacturer and you got a shot with excessive accelerator in it. There's an additive we put in the part A of epoxies which controls how fast it cures/reacts. I can make it cure in 10 secomds if I want, or leave it out and it takes hours. It's used in such miniscule amounts, that if not mixed in properly, it can have the same effects you experienced. And when it's used in higher percentages, it does generat tremendous heat. I've melted polyethylene mixing cups when I made a super-fast set epoxy sealant.