I am curious to know if anyone else has had the same experience as me when mixing resin. Every now and again I get a bad mix from some contamination. In this video I have used some resin I already knew was contaminated from an earlier mix. I had left a small amount out uncovered for a few days. I suspect contamination came from either moisture of vapour from fly spray.

Tony when you mix the two substances does it generate a highly exothermic reaction? It looks like the moisture is being boiled away.

I've had this problem with epoxies before.

My chemistry is not up to much and I really don't know. I think it is setting at the same time as giving off a gas. So there is a point where the gas struggles to get out. I didn't notice any extra heat though I didn't touch it until the end.

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... At least you could make a cool video out of it.

By the way... Red Golden Cube...?

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.