Popular Science, heinäkuu 1942
Workers who build Lockheed planes now are protected by a safety-first color scheme applied to their machines. Moving parts are identified by cream-colored paint, and stationary parts by gray, as in the brake for bending sheet metal shown at right. [KUVA PUUTTUU] In other applications, suitable colors make control levers and knobs more clearly visible. Fourteen daylight trials show the best contrasts to be black agains a yellow background, and green against white; the worst, red against green, and blue against red. Among industries using complicated piping systems, paints of different colors long have been used to distinguish pipes carrying water, steam, gas, refrigerant, acid, and various other chemicals.