Made this heavy BronzClay ring assuming that I had understood what went wrong previously. The ambient temperature was 47F when I turned the kiln on (it’s cold at Resistor on the weekends), so I added 20 degrees and an hour to the regular program — kinda like baking a bigger bird. Well, it looked good out of the charcoal until I hit it with the brass brusher, or maybe I should say the brass crusher. I quenched it when the temperature was around 500F, so that little bit of moisture combined with the bronze powder to make mud in a thin metal shell.
Back to the drawing board on the kiln controller.