the first result ( RTO tool ) the lid was only partially lifted by a few mm, the crucible cooled very quickly; as in by the time i had grabbed a screwdriver from 4 feet away it was cool enough to pry off. - The lid is never violently blown off and i introduce the crucible to the quench quickly and the box entering at something shy of 90 degrees the pressure seems to do the rest.
True the crucible does create a lot of scale and has a limited lifespan; my crucible is a steel tray made from bending some ~2mm sheet steel, its about 4 inches high by about 5.5inch square, its drawn onto the steel like a box packed flat, the lid is just a square piece of the same steel that sits inside the tray and is sealed in place by clay.
The biggest issue with the process is the BBQ charcoal, its of the "light in the bag" variety and im sure it has some parafin or something on it to help get it going, this finds its way out of the crucible - it would be an interesting experiment to see weather using special charcoal VS this BBQ stuff would yeild different results. I don't have the time or funds at the moment to conduct this as an experiment but may do in the future.
