temper color

noun

, Metallurgy.

1. any of the colors appearing on the surface of clean, unoxidized steel heated in air, from pale yellow at the coolest to dark blue at the hottest: used as an approximate indication of temperature.

Example Sentences

If there is a distinct boundary line of temper color between the hard cutting edge and softer shank portion, it will be very apt to break at or near that line.

From Project Gutenberg