FWIW I regulary bake 1/2 & 1/4 inch 456 in an old kitchen oven with
the aid of a small themometer. I try and keep it at 50 degrees Celsius
(whatever that is in American) with regualar checking, and usually can
play the tape after 3 - 4 hours. I don't bother cooling it. If for any
reason it's still gunky, I'll stick it back in for another 3 hours.
Works well.
Good luck
Cheers
David