Materials

The Pile Synthetic materials are never used in the pile or foundation of handmade rugs. Wool, silk, or a combination of the two are the traditional materials used. Dyed wool is customarily found in tribal rugs, and depending on the region, will vary in quality. Persian rugs, especially older pieces, have the absolute finest and softest wool while in Turkish and Indian rugs, the wool tends to be coarser. Most Chinese rugs are made of silk, primarily because China is the world's leading producer of both natural and manmade silk, and also because the Chinese once believed that the use of wool was a barbaric practice.

Today, the finest rugs are made of silk, and the most luxurious Persian rugs may actually feature highlights containing threads of pure gold.

The Foundation - Warp and Weft The foundation of a handmade rug is made up of strong threads that run the length (warps) and the width (wefts) of the carpet. In Turkish and nomadic rugs, including those from Western Iran, tightly spun undyed wool is used almost exclusively for the warp and weft. The foundations of finer pieces from Persian workshops today are often cotton, and only the very finest rugs in Iran are woven on silk.

The Fringe At either end of the carpet, the warp may form a variety of fringes. The weaver decides how they will shape the fringes, either by braiding, knotting, or simply twisting it. The type and length of fringes is not a standard characteristic of rugs of the same area and the fringes have nothing to do with the quality of the carpet.

The Dyes Until the introduction of chemical dyes in the late 19th century, only natural color sources such as fruits, vegetables, bark, roots and fungi were used. The most commonly used vegetable dyes are indigo (originally obtained by extracting and fermenting indican  from the leaves of the indigo plant), madder (produced by boiling the dried, chunked root of the madder plant in the dye pot), and larkspur (produced by boiling the crushed leaves, stems, and flowers of the larkspur plant). These dyes produce, respectively, dark navy blue, dark rusty-red, and muted gold.
Chemical dyes are more popular today but natural dyes are still common in Persian tribal rugs. Before wool is dyed, it is prepared by scouring in boiling water followed by steeping in a mordant. Next, it's placed in a big pot with the prepared dye and boiled for a few hours. It is then rinsed in water until there is no more running of color.
Long ago dyers realized that as more wool was dyed in a single depot, colors became weaker and weaker. Dyers use this notion of depleted dyes to their advantage. The first dyeing produces a deep, strong color. Subsequent dyeings in the same dye pot produce lighter, softer colors. Dyers also quickly learned to combine colors to produce different hues. There is, for instance, no "vegetable" dye material that yields green. First dyeing wool blue, then dyeing it again with yellow, does produce a green color. If you look closely at the green color in a vegetable-dyed rug, you will commonly see that the color is uneven, more blue-green in some areas, and more yellow-green in others. This is because of the double-dyeing technique.
By using the notion that depleted dyes produce different hues and by combining some dyes through over dyeing wool, dyers can produce a surprisingly large palette of colors from a very limited variety of materials. Although natural colors are fast, they do fade slightly over the course of time when exposed to direct sunlight and alkalis. This fading, however, produces a muted antique look which many people desire, and which cannot be equaled with chemical