Can't count how many times I've yanked em(various woods used) off a form an hour later or less and immediately went to finish tillering n shooting etc....n I've seen plenty of yins others guys(won't say names cough cough) do the same with no I'll results.... ....heck its hickory....once its cool take it off the form and start bending that beech
I popped a back ring on the first Elm I ever heat-treated when I started this whole heat-treating thing back in the early 2000's by doing just that. Now I wait
What was the mc of the wood before you tempered it? Did you weigh it before and after? Did you blacken the belly? Was it over cooked and caused the back to become brittle? Heck Marc..it was your first time...it could have been other reasons than blaming mc loss... I've just seen way too many bows made with wood at 8-10% mc tempered and finish tilllered before it was 24 hours from being tempered....like I said I weigh all mine before and after tempering and a tenth of an ounce lost at the most means very little actual mc drops in the wood...the numbers don't lie(to me at least)
I think it was a year or 2 after I wrote that first article one of the members, I believe it was Lennie (Tom Sawyer), did some tests on moisture loss after tempering. His tests indicated that the actual amount of moisture lost from the process was miniscule and not worth considering, he was using seasoned, dry wood but I don't remember which type. The bulk of the moisture loss is on the outer surfaces. Back then I didn't measure the MC of wood, still don't, I just monitor(ed) the RH of my environment.
Overcooked??? Really??? Could have been, might have been....naah I don't think so. The Elm was high quality Elm with decent growth rings plus I had no trouble with the other staves from the same tree. I'm not saying that you will pop a back ring every time but all it takes is once to ruin your day.