Are bubbles in my seal coat normal, and should I use heat on them?

Yes, air bubbles in the seal coat are normal, and you do not need a heat gun or torch to remove them. The seal coat is meant to be recoated within 4 to 6 hours, while it is still tacky, so the bubbles are not trapped; the next coat simply covers them. Excess heat on a seal coat can pull more air out of the wood and cause white spots.

If a lot of white bubbles keep rising from deep in the wood, the surface is very porous and needs two or three seal coats, spaced 4 to 6 hours apart, before the flood coat. Bubbles do not mean a bad mix (incorrectly mixed epoxy would not be hardening at all), though air whipped in while mixing can add them.

After 10 hours, the seal coat has hardened with the bubbles in it. Sand it with 220 to 320 grit, wipe off the dust with a clean rag and denatured alcohol or acetone (never mineral spirits), then apply the next seal coat or the flood coat; it fills the scratches and cures clear. Do not sand through to bare wood; if you do, seal coat again first.

Mixing tip: UltraClear Bar & Table Top Epoxy has a 5-minute pot life, so mix seal-coat batches under 1 quart by hand with a stir stick; a batch left in the container heats up and sets. You then have 20 minutes to mix the next batch and continue seamlessly.

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