urdimbre

Urdimbre is the set of lengthwise yarns in a woven fabric, held under tension on a loom. In English, the term is warp; urdimbre is the equivalent term used in some languages, notably French. The warp runs from one end of the loom to the other and provides the fabric’s structural backbone.

During preparation, warp yarns are chosen for strength and dimensional stability and are wound onto a warp beam through a process called warping. The warp is often sized to reduce friction during weaving. On the loom, the warp threads are threaded through heddles and arranged to form a shed, through which the weft is inserted and interlaced with the warp to create fabric. Modern looms may employ automatic warp let-off and shedding mechanisms to control tension and patterning.

Properties and fabric structure are influenced by the urdimbre. The density, fiber type, and finishing of the warp affect strength, rigidity, and elastic behavior. Fabrics can be warp-faced, where warp yarns dominate the surface, or weft-faced, where weft yarns are more prominent. The warp’s quality and arrangement also interact with weave structures such as plain weave, twill, or satin to determine drape and texture.

Applications and techniques vary across textiles. Weaving technologies such as rapier, projectile, and air-jet looms manipulate the warp to produce complex patterns and efficient production. Patterning in weaving may involve the warp, the weft, or both, with techniques like dobby or jacquard enabling intricate designs. Across cultures, urdimbre has historically been central to fabric production and textile trade.