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
this table leg). The Scale Model EXchange have an interesting color spectrum of the various colors that steel takes on, during the process of heating which forms “an oxide layer…on the …blog.adafruit.com