Why did my epoxy get hot and harden in the mixing container?

UltraClear Bar & Table Top Epoxy has a 5-minute pot life, and the clock starts when you finish mixing, not when you start. A 1-gallon batch takes 5 to 6 minutes to mix; then you have 5 minutes to get it out of the container. Leave it in the bucket longer and it overheats, thickens and flash-cures where it sits. Once that reaction starts, the epoxy cures uncontrollably.

The usual causes:

1. Waiting too long to pour. Start pouring as soon as mixing is complete. The epoxy is self-leveling, so it does not need to be rolled or spread; poured within the pot life, it levels to a smooth 1/8" coat, and you have about 20 minutes of working time on the surface before it begins to gel. 2. Mixing too much at once. The maximum batch is 1 gallon combined (1/2 gallon resin + 1/2 gallon hardener). Larger batches overheat in the container. 3. Degassing the batch. Vacuum chambers and bubble removers are not needed with our epoxy, and a few minutes in one uses up the pot life. Mixed and applied per the directions, it gives bubble-free, glass-like results without one.

Mixing several colors? Put the hardener into each cup first, stir in the pigment, and add the resin only when you are ready to pour that color: https://ultraclear.helpscoutdocs.com/article/80-epoxy-color-pigments

Need more time? UltraClear Art & Craft Epoxy has a 30-40 minute working time; still begin pouring right after mixing.

Bar & Table Top Epoxy Instructions: https://cdn.shopify.com/s/files/1/0320/7168/0140/files/Epoxy-Instructions.pdf?v=1616443869