When I first started work in 1977 some of the old guys could tell you the temperature of steel by looking at it as accurately as the pyrometers (disappearing filament) of the time. Coded welders have an uncanny ability to tell the temperature of steel between 50 and 150C just with their hands.The Color Spectrum of Heated Steel
When heating steel you may notice changes in color on the material (such as in a picture during the bending of this table leg). The Scale Model EXchange have an interesting color spectrum of the va…blog.adafruit.com