Why did my seal coat get thick and gum up while brushing it on?

The batch was bigger than you could brush out in 5 minutes. UltraClear Bar & Table Top Epoxy has a 5-minute pot life once mixed; anything still in the container after that starts to overheat and flash-cure, and quickly becomes too thick to brush.

Brushing a seal coat is slower than pouring a flood coat, so keep seal coat batches to 1 quart or less, as the instructions specify; smaller is fine. Flood coat batches can be up to 1 gallon, because you only pour them on and let them self-level. You have a 20-minute window after the epoxy is applied to mix a new batch and continue where you left off, so the batches blend into one seamless coat.

Do not try to slow it down with less hardener. The epoxy only works at a 1:1 ratio.

If gummed-up epoxy got onto the surface, scrape off as much as you can before it gels. If it hardens but looks cloudy, sand it down before applying a new seal coat. If it stays tacky for more than 24 hours, apply the next seal coat directly over it.

Air bubbles in a brushed seal coat are normal and need no torch or heat gun. Lots of bubbles means a very porous surface; two or three seal coats may be needed before the flood coat. Re-coat within 4 to 6 hours with no sanding; after 10 hours, sand with 220-320 grit and clean with acetone.

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