in the early 1980s. Chemical analyses led to the identification of natural dyes from antique wool samples, and dyeing recipes and processes were experimentally re-created. According to these analyses, natural dyes used for carpet wool include: Red from Madder (Rubia tinctorum) roots, Yellow from plants, including onion (Allium cepa), several chamomile species (Anthemis, Matricaria chamomilla), and Euphorbia, Black: Oak apples, Oak acorns, Tanner's sumach, Green by double dyeing with Indigo and yellow dye, Orange by double dyeing with madder red and yellow dye, Blue: Indigo gained from Indigofera tinctoria. Some of the dyestuffs like indigo or madder were goods of trade, and thus commonly available. Yellow or brown dyestuffs more substantially vary from region to region. Many plants provide yellow dyes, like Vine weld, or Dyer's weed (Reseda luteola), Yellow larkspur, or Dyer's sumach Cotinus coggygria. Grape leaves and pomegranate rinds, as well as other plants, provide different shades of yellow. In Iran, traditional dyeing with natural dyes was revived in the 1990s, inspired by the renewed general interest in traditionally produced rugs, but master dyers like Abbas Sayahi had kept alive the knowledge about the traditional recipes. Insect reds Carmine dyes are obtained from resinous secretions of scale insects such as the Cochineal scale Coccus cacti, and certain Porphyrophora species (Armenian and Polish cochineal). Cochineal dye, the so-called "laq" was formerly exported from India, and later on from Mexico and the Canary Islands. Insect dyes were more frequently used in areas where Madder (Rubia tinctorum) was not grown, like west and north-west Persia. Synthetic dyes With modern synthetic dyes, nearly every colour and shade can be obtained so that without chemical analysis it is nearly impossible to identify, in a finished carpet, whether natural or artificial dyes were used. Modern carpets can be woven with carefully selected synthetic colours, and provide artistic and utilitarian value. Abrash The appearance of slight deviations within the same colour is called abrash (from Turkish abraş, literally, “speckled, piebald”). Abrash is seen in traditionally dyed oriental rugs. Its occurrence suggests that a single weaver has likely woven the carpet, who did not have enough time or resources to prepare a sufficient quantity of dyed yarn to complete the rug. Only small batches of wool were dyed from time to time. When one string of wool was used up, the weaver continued with the newly dyed batch. Because the exact hue of colour is rarely