By Dan Brady [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
Dying is more art-form than science. Dyers occupy an elevated position in weaving societies and pass their secrets from generation to generation. Since traditional dyes are derived from local resources, each region will display a traditional color palette in its rugs. For instance, the villages of Hamadan, Lilian, and Sarouk in central Persia (Iran) are known for their sublime pinkish dye, which dominates their rugs and is produced by boiling madder root with yogurt. Lavar is known for its indigo dye. In some places such as Baluchistan, where dyestuffs are scarce, weavers have become highly skilled at combining yarns with different natural coloration. Most dyes from natural sources need a “mordant”, or fixative, in order to bind to the yarn. Common sources of red dyes are madder root and cochineal (exudate from insects feeding on plant sap). Blues are often derived from indigo or possibly aubergine skin. Yellows may come from the flowering native plant called isparak, or from saffron, turmeric, apricot leaves, or wild pistachio trees. Orange may be derived from grass root, plum tree bark, poplar leaves, or willow leaves; green from walnut leaves, olive leaves, or sweet violet; browns and blacks from tea, tobacco, mud, walnut bark, or wild pistachio leaves. Wool may be double-dyed to arrive at the desired shade. Madder-dyed yarn dipped in pomegranate husk solution produces orange and double-dyeing any yellow with indigo will produce green. Natural dyes retain their color well and gently fade over time as they acquire the mellow patina of age, so admired in antique rugs. In contrast to natural dyes, chemical (i.e., synthetic) dyes look harsh, corrode wool, tend to fade quickly, and often bleed easily when washed.