Wool is the dominant material used in Oriental rug pile, and its quality is one of the most important factors determining a rug's beauty, durability, and value. Not all wool is equal, rug-grade wool varies enormously based on multiple factors.

Factors affecting wool quality:

  • Breed of sheep, different breeds produce wool with different fiber characteristics. Persian, Turkish, and Tibetan highland sheep produce particularly desirable wool.
  • Climate, sheep raised in cold mountainous regions develop longer, more lanolin-rich fleece. The wool from Iranian and Anatolian highland sheep is especially prized.
  • Part of the fleece, wool from the shoulder, back, and sides of the sheep is generally finer than wool from the belly or legs. The finest wool of all is called kork (Persian word).
  • Age of the sheep, wool from young sheep (especially lambs) is softer; wool from adult sheep is more durable
  • Season of shearing, spring-sheared wool, from sheep that have grown a full winter coat, is generally the highest quality
  • Spinning method, hand-spun wool (yielding uneven thickness that takes dye more variably) is prized in tribal and village weaving; machine-spun wool (uniform) is standard in workshop production

Notable wool categories in rug weaving:

  • Kork wool, the finest wool, taken from the underbelly and neck of the sheep; soft, lustrous, takes dye exceptionally well. Used in fine Persian Kashan, Tabriz, and Nain rugs.
  • Manchester wool, a high-grade English worsted wool used in some Persian rugs (especially "Manchester Kashans") in the early-to-mid 20th century; very fine and lustrous
  • Merino wool, fine wool from Merino sheep; used in some Australian-import rugs and contemporary production
  • Tibetan highland wool, long-staple, lanolin-rich wool from sheep raised at high altitude; the foundation of authentic Tibetan rugs
  • Local village wool, varies enormously in quality; in tribal and village rugs, the local wool is part of the rug's regional character

How to evaluate wool quality in a rug:

  • Luster, high-quality wool has a natural sheen; very dull wool may be poor grade or chemically washed
  • Hand feel, soft and resilient is good; harsh, brittle, or limp is not
  • Lanolin content, high-lanolin wool feels slightly oily and develops a beautiful patina with age
  • Spring, pressing the pile should leave wool that springs back, not flattens permanently
  • Dye absorption, high-quality wool takes natural dyes with rich depth and color variation

Rugs made with high-grade wool age beautifully, developing a softer hand, deeper color, and natural luster over decades. Rugs made with poor-grade wool tend to feel harsh from the beginning and may wear unevenly.