The appeal of a rug has always depended on the colors of the dyes - their brightness, muted colors, reds, greens, indigo, orange and on and on. Originally all dyes were made the from natural sources such as madder red came from the root of the madder plant, cochineal red from the cochineal insect, yellow from the weld plant, vine leaves or pomegranate peal, brown from the walnut shell or oak bark, orange from henna leaves, blue from the indigo plant and green from a combination of weld and indigo. There are people today who still use the original items to dye yarn and the colors are fabulous!
In 1856 aniline dye was discovered in England by William Henry Perkin. The early color was violet and soon were followed by many more shades and colors. These proved to be popular because suddenly there were plentiful easy to use dyes. However these were very unstable and colors and faded into unwanted shades. Blues turned to brownish grey, red to mauve and yellow became an awful greenish brown.
During this period of time the Oriental Rug market became very unstable as people stopped buying the rugs. In 1903 the use of aniline dyes were banned in Persia with severe penalties for those who did continue to use them.
The 1920’s and 30’s brought new synthetic chromatic dyes with extremely good results. The quality of this new dye was very good and actually became more reliable than the natural dyes.
Natural dyes are not used as much now in the weaving of rugs but there is a project in Turkey - The Dobag Project - which encourages weavers to use vegetable dyes.