September 26, 2015 8:39 PM EDT
Hi Mary Rose,
Undercoat fires pretty standard- same as Foundation, which is the other white I've had the most experience with. Antique white seems to be a very slow to melt white but I've had limited experience with it so I'd need to verify that with more tests. I typically use Undercoat but if Antique does prove as hard to melt as I think it might be a better base layer in future. I make jewelry so my average time to fire, for example, is about 1.5 to 2 minutes at 1450-1500F for a piece that might range between 1 to 2 inches in diameter. That's just a rough average but I hope that helps!