In 1917, NIST physicists Irwin Priest and Chauncey Peters were drawn into the so-called Butter War, an early 20th century commercial and political spat between the dairy and margarine industries. Seeking to protect dairy producers, some states passed laws banning the dying of margarine yellow. Yellow dye was commonly added to naturally clear-colored margarine to make the product appear more ‘buttery.’ (Some butter makers also used yellow dye for the same reason, but no matter.) The problem for the dairy industry and their political supporters was how to strictly define what is ‘yellow,’ apart from the experience of the viewer. They turned to NIST for help. While reluctant to get involved in a commercial dispute, NIST realized that precise physical standards for color would be important to many industries, including paints, textiles, paper, porcelains and enamels, petroleum and chemicals, cement, flour and sugar, water purity, and for colored glasses for signal lamps and eye protection.
Priest and Peters 1917 paper defined yellow in terms of a product’s ability to reflect light of specific wavelengths. By legally specifying that a product could not reflect light in these wavelengths, Priest and Peters note, “in practice, will not allow [for] saturated tints of yellow.” But NIST wasn’t taking sides. Priest and Peters paper includes an introductory note from NIST director Samuel Stratton: “While it is a part of the Bureau's proper duties to furnish upon request technical advice such as is given in this paper, the Bureau expresses no opinion in regard to the advisability, propriety, or justice of any proposed legislation incorporating this specification.”
The last state margarine-color law was repealed in 1967.