Vertical Loom H orizontal Loom Persian pile rugs and carpets are hand-knotted on foundation formed by warp and weft threads. During the weaving process the warp threads are attached to the upper and lower beams of the loom. They run vertically through the body of the carpet. A strand of wool as looped around a pair of warp threads, forming a knot. The loose ends of the knots make up the body of the carpet and are called the pile.
Weft threads run horizontally through the carpet and are used to secure the rows of knots in place.