I shouldn't tell this , but since you mentioned kaseinite ,here goes. .......When first playing around with a 1970 era Dixie percussion lock that the tumbler was so soft , just working the lock through its mechanical action caused the main spring to trench a groove in the slope of the tumbler. Knew the tumbler needed hardened , but not what to do. Only resource was the Dixie G.W . catalog and in it was Kasenite , w/instructions. Was working in an apartment with some hand tools , kitchen table , and a gas range. Since this was 50+ years ago I think the instructions said to heat the metal to a certain color , and bury it in the Kasenite until cool or something like that. I do remember it took three times repeating the process and accidental , perfection. That sucker was hard , the lock worked...............oldwood