Question about black industrial finish

[65 Malibu SS]

Hello all. I've really enjoyed reading this forum over the last few weeks. My first post is a question. When was the black industrial finish first used and more specifically when would you first expect to see it on the Armstrong ratchets? Thanks in advance.

 

[Packard V8]

FWIW, I've never personally seen an Armstrong ratchet with the black industrial finish. Sometimes, it's difficult to tell on older tools if they had a black finish which is very worn, or if they were a plain unfinished steel which has just worn smooth. I have seen Armstrong tools which were sold unfinished.

jack vines