"spaco" wrote in message
news
I assume you are talking celcius, since Fahrenheit temps in that range
would yield dark straw to red. At, let's say, 475 C (887 F), you have
just about run out of temper colors. So, if you are only approximating
this temp range(450 to 500), you may be getting things a little hotter than
you used to be doing. You need to be down at about 350 C to get blue, I
think.
I also agree that the lubricant may be protecting the metal from
oxidizing.
Lastly, I forget what "nickel silver" is, but I don't think it contains
any silver anyway. If it did contain silver, then all bets are off.
Isn't it British slang for something like O1 tool steel?

Pete Stanaitis

You're thinking of "silver steel." Someone posted the makeup of nickel
silver (it used to be known as "German silver" in the US). It's copper and
nickel, and, in most formulations, zinc.

I posted something dumb in this thread earlier because I didn't notice that
nickel silver was the subject. I was thinking steel. However, nickel and
copper also form oxide colors from heating. I just don't know how the colors
relate specifically to temperature.

--
Ed Huntress