cudbear

Cudbear is a historic purple textile dye derived from lichens. It was widely used in Europe from the 18th century into the 19th century for dyeing wool and silk, and it became associated with the British and Scottish dyeing trades. The dye is typically produced from lichen species such as Rocella tinctoria and related taxa, which yield reddish-purple pigments that are extracted and applied to fibers.

To fix the color on textiles, mordants such as alum (potassium aluminum sulfate) or iron salts are used. On protein fibers like wool and silk, cudbear provides relatively bright purples and good dye uptake; on cellulose fibers such as cotton, color fastness is poorer unless stronger mordants or additional treatments are used. The exact shade depends on the mordant, fiber type, and dye concentration, ranging from pinkish purples to deep violet.

In historical practice, cudbear was marketed as a commercial dye and was one of several lichen-based purple dyes used before synthetic alternatives became prevalent. Its popularity declined after the development of aniline and other synthetic dyes in the late 19th and early 20th centuries. Today, cudbear is of interest mainly to historians of textiles and to natural-dye practitioners who study or recreate historical dyeing techniques.