All these propellers have been hardened after annealing to allow pitching. Anneal C-20 beryllium copper by heating to 1450 deg. F (dull red) in a dark room. Quench immediately in ice cold water. If the props are heated to hot during annealing, the beryllium will leach out & the blades connot be hardened. I re-anneal finished balanced pitched props to ensure stabilization before hardening.
