clarence said

Zebulon said

From Dunlop’s chapter on bluing, I’ve learned that “Carbonia” was the name of a pre-mixed powder containing charcoal and other materials,  sold by the American Gas Furnace Company.   

That’s a logical name for their product, but I think the term was in use before the machine bluing process was developed; would be interesting to know if they trademarked, or tried to, that name.  None of my gunsmithing books discuss the machine process, because it’s not suitable for small shops; easier to rust blue a few parts at a time.

  

Could be, I’m not sure I can do a trademark search with the limited access I have now.  I can guess powder form would have been a time-saver if you intended to use it in a rotating over.  I do know that Sperm whale oil was relatively expensive and became more so.  Dunlop puts various rusting formulae under the heading, “Cold Blue” — which is right enough.