The lichens thus treated acquire gradually a deep purple colour, and form the products called "cudbear."
If the red color of the wool is due to archil or cudbear, it is extracted by hydrochloric acid, which is colored red.
Instead of logwood a little madder is sometimes used; also cudbear or Barwood.
If the colour is not good, tincture of red sanders or cudbear is directed to be added.
A mordant of alum, followed by a hot bath of brazil wood, and afterwards by a weak one of cudbear.
Dye with equal quantities of cudbear and Logwood, the wool having been mordanted with chrome.
Various species of Lecanora, particularly L. tartarea, known as cudbear, are used in dyeing woollen yarn.
The manufacture of Archil and cudbear from the various lichens is simple in principle.
About 130 tons of cudbear are imported annually from Sweden.
The above deep red feathers are passed through a bath of cudbear.