Before synthetic dyes were introduced in the late 1800’s, Oriental rugs were dyed with colors extracted from the surrounding environment including plants, minerals and even insects. These dyes are usually called vegetable dyes. At an early age people are taught mixing yellow and blue makes green. This well-known fact was also applied to antique Oriental rugs made with vegetable dyes.
The color blue was obtained from the indigo plant. After dyeing the wool blue, it was dyed yellow. Yellow dye was often obtained from various flowers including Saffron, Larkspur, vine leaves, and buckthorn. It is easy to differentiate a green in a vegetable dyed rug versus a synthetic dyed rug by the uneven color in the vegetable dyed rug. Since the wool has been dyed twice the green color in a vegetable dyed rug may have a slightly blue hue in one area and a yellow hue in the other. The synthetic green will be more uniform. Often times, the yellow may fade leaving blue on the pile. If you gently pull the pile apart to an area which has not been exposed to sunlight you will see the color was once green. Yellow splotches may also appear in a vegetable dyed rug from wear which causes the indigo color to rub off over time. Other, less common, sources of green dyes include turmeric berries, and Buckthorn berries which are used to produce Chinese green. In China, the color green signifies renewal and growth.
The strength of the color is determined by several variables including the time the yarn spends in the dye pot, the type of spring water used, and the type of mordant used. Green fields are very rare in antique Oriental rugs because green is a holy color in Islam and is rarely walked upon. Since saffron is so expensive and yellow dye is required to make green, the rarity of yellow can also contribute to the lack of green rugs. Green has become more common in Oriental rugs in the last 100 years or so with the introduction of synthetic dyes and the increasing demand for it.
Other Oriental rug dyeing resources: