More about Natural vs. Synthetic Dyes
There is agreement among nearly all old-rug collectors that natural dyes in a rug are better than synthetic. But the issue is clouded by the fact that often it is impossible without expensive laboratory analysis to be certain whether a given dye in an old rug is natural or synthetic. So much has been written about natural dyes vs. synthetic (see Oriental Rugs Today, Emmett Eiland, Berkeley Hills Books) that I will not tackle the subject here. But I believe it is safe to say that no rug buyer will ever regret acquiring a rug or carpet with well applied natural dyes. Natural dyes definitely add to the cost of a rug, but they also add to its value.
Hand Spun vs. Machine Spun Wool
For thousands of years, weavers spun wool by hand to create the yarn that makes up the pile of Oriental rugs. By about World War Two, nearly all wool was spun by machines. Now, since about 1985, a small but appreciable number of weavers are again spinning wool by hand. Though a few people prefer the uniformity and formal appearance that machine spun wool imparts to carpets, most collectors and connoisseurs value the effect produced by hand spun wool. When spun by hand, yarn absorbs more dye where it is loosely spun and less dye where it is spun tightly, thus producing pleasant variegation in the colors of a rug. Though there is room for disagreement, I believe that the best Oriental rugs are woven with hand spun wool.