For the past few decades, the vast majority of so-called Persian and Oriental rugs of "commercial" grade, have been produced with chemically dyed wool. In fact, the significant costs of preparing natural dyes have made the use of chemical colors somewhat tempting. However, master weavers and producers of higher quality Persian carpets and Oriental area rugs have come to the natural dyesconclusion that natural dyes are a "necessity" if they are to achieve desired levels of quality in their production. They clearly witnessed that vegetal colors simply improve with time, whereas chemical dyes stay the same in soft light, but fade or are dulled by prolonged exposure to sunlight. A hand-knotted rug by a master weaver can often be authenticated by its colors. The time-consuming process of preparing natural dyes, resulting in the relatively higher cost of preparing them is briefly explained below.
Natural dyes, first discovered by shepherds and farmers many centuries ago, are extracted from plant or animal substances and fall into either one of two categories. The first are naturally colored, the second need to be put through a rather complicated process in order to reveal their coloring properties. Producers and master weavers of high quality area rugs still use natural dyes, mixed by themselves or by working closely with a selected and trusted master dyer committed to their workshop. The ingredients, doses, and quantities used for the range of dyes are, naturally, a closely guarded secret. It is almost impossible to copy a color. As a new batch is needed for the continuation of the weaving, it is almost never going to be of the exact same shade given out by the previous batch. This results in variations of colors in hand-knotted Oriental and Persian rugs - called abrash within the rug industry - and not at all considered a defect.
Master dyers use colors extracted from bark, roots, stalks and dried leaves, ground into a powder. For example, the dried skin of a pomegranate, a cream color in powdered form, is going to produce a matt yellow color. Powdered walnut hull will color from a range of browns to black. Dried vine leaves will offer a range of colors from khaki to grey, and ground twigs of weld or sparrow grass achieve a strong, golden yellow that is particularly bright on silk. Also, the roots of the madder plant give a widely known red or rusty red (Rounas).
The raw material in its powdered state is inserted into a bath of cold water which is then heated in order to release the coloring agents. It is then left to cool down to allow the color to dissolve. The hanks are inserted into the water at room temperature in order to avoid a thermal shock which would damage the fibers. They are then gradually brought to simmering point for a specific length of time depending on the shade desired. According to the nature of the raw material and the natural dyescolor required, different mineral salts are added which alter the PH of the bath and allow the color to fix onto either the wool or the silk.
Unlike natural colors, chemical dyes are readily available, do not require painstaking processing, and are therefore less costly to work with. However, top producers insist on their use in their high quality products as no other substitute has yet been discovered. With the revival of natural dyes into the production of many Persian carpets and Oriental rugs being produced today, the future of the rug industry seems to be much more promising now compared to only twenty years ago. The best rugs woven today are sure to become heirloom pieces of tomorrow.