How deep can I pour in a mold at once, and when can I demold?

It depends on the product, but none of them demold quickly: every UltraClear epoxy needs its full 72-hour cure before you pull the piece from the mold, so nothing demolds in 20 minutes or even 24 hours.

UltraClear Bar & Table Top Epoxy: 1/8" per layer, with the next 1/8" layer added 4 to 6 hours later. A 1" casting would take 8 pours, so use Deep Pour for anything that deep.

UltraClear Art & Craft Epoxy: 1/8" or 1/4" in a single pour, with additional pours after 4 to 6 hours. It is dry in 12 hours but cures in 72 hours; don't demold until the 3 days are up.

UltraClear Deep Pour Epoxy: 1" per pour, with additional 1" layers every 12 to 24 hours, up to 6" total. The product page allows up to 2" in a single layer and experienced users pour 2" regularly, but if you are new to it, stick to 1" increments to reduce the risk of overheating. Keeping the room around 60 to 70°F also helps. It cures in 3 days.

No vacuum chamber is needed. Mix slowly by hand with a stir stick for batches under a gallon so you don't whip air into the resin, then pop the bubbles with a heat gun or propane torch. In a deep mold, pouring Deep Pour in 1/4" increments up to the final depth makes bubbles easier to pop than pouring the full 1" at once.