FAQs about Blacksmithing and Metalworking
(This sounds good)
A primitive method is to use a small pine stick and see when it
chars in the melt. . . I think this is 450 to 500 F.
A more accurate but primitive method is to make a bunch of
polished plain carbon steel "coupons". You hold half of one of
these in the melt with light tongs and watch the temper colors.
When the colors stop changing it is at the melt temperature.
Compare the temper colors to a temper color chart similar to the
one we have in our FAQs. This will give you fairly accurate
readings from 420 to 640 F.