archil

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Scope note
A natural dye that is bright red to rich purple color, obtained from any of several lichens; used as a pigment, textile dye, wood stain, food colorant, and an indicator dye that turns blue in alkaline solutions. It was by the ancient Egyptians; the preparation was rediscovered by the Italians and used to make the brilliant red and purple Florentine cloth. In the18th century a Scottish chemist C. Gordon patented the process, which he called "cudbear." The dark red color in archil is formed when lecanoric acid is converted to orcein by fermentation then oxidation.
archil
Accepted term: 22-Apr-2024