Cudbear

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Cudbear is a dye extracted from orchil lichens that produces colours in the purple range. It can be used to dye wool and silk, without the use of mordant.

Orchil, also called archil or orcein, is another name for a purple dye obtained from lichen. It was the "poor person's purple", used instead of overpriced Tyrian purple, or as an initial "bottom" dye to greatly reduce the consumption of Tyrian purple. Use of orchil dyes was described by Theophrastus and Discorides. [1]

Cudbear was developed by Dr Cuthbert Gordon of Scotland: production began in 1758, and it was patented in 1766. The lichen is first boiled in a solution of ammonium carbonate. The mixture is then cooled and ammonia is added and the mixture is kept damp for 3-4 weeks. Then the lichen is dried and ground to powder. The manufacture details were carefully protected, with a ten-feet high wall being built around the manufacturing facility, and staff consisting of Highlanders sworn to secrecy. The lichen consumption soon reached 250 tons per year and import from Norway and Sweden had to be arranged.[2]

Cudbear was the first dye to be invented in modern times, and one of the few dyes to be credited to a named individual.

Similar process was invented in France. The lichen is extracted by ammonia. Then the extract is acidified, the dissolved dy precipitates and is washed. Then it is dissolved in ammonia again, the solution is heated in air until it becomes purple, then it is precipitated with calcium chloride; the resulting insoluble purple solid is known as French purple, a fast orchid dye that did not fade in light like the other lichen dyes.

Cudbear is also the name of the lichen Lecanora tartarea (syn. Ochrolechia tartarea, Lichen tartarea) from which the dye is extracted.

See also:

• Ethnolichenology
• Lichen dye photos