Modern-Day Warrior wrote:
Woah. Good tip to keep in mind for any casting puzzlemakers. Looks like a delayed vinegar/baking soda reaction; I doubt it was extra moisture actually being boiled. I wonder what exactly was the contaminate in this case
This is the most violent reaction I have had. A small amount of water certainly courses some frothing which is enough to ruin the part. I didn't recall this happening when I used to use polyester resin. A bad mix meant it wouldn't set properly or the surface stayed tacky.