Temperature-indicating Paints
A 1939 NASA Technical Memorandum on temperature-indicating paints, issued by the National Advisory Committee for Aeronautics for engineers and researchers testing heat distribution on machine parts. The pictures are line drawings of a piston, a heating pipe, a fitting and a stove-top burner, each overlaid with dashed boundary lines and labelled with thermocolor numbers and temperature ranges such as under 65 degrees or over 220 degrees. A designer could take from them the idea of colour-coded zones that map heat as clear regional boundaries.
