Hand-spun wool, although very labor-intensive and far more expensive than machine prepared materials, is used in the highest quality carpets. This is due to the fact that the human touch gives the wool a twist, which textures the yarn with an uneven diameter. This uneven diameter absorbs color differently, leading to striation of color called "abrash". A sort of abrash also results from having used the wool of several different sheep, which may make the color of the carpet change in tone from one end of the carpet to the other. This asymmetrical product ultimately produces a carpet pile that is more interesting and aesthetically pleasing to the eye. Additionally, the hand spinning adds strength to the yarn itself. After the wool is spun, it is prepared for dyeing.