Textile Glossary : Weaving The - Fabrics
A weave is a right-angle structure, created by crossing two threads – a warp thread and a weft thread.
Origins
The oldest examples of weaving trace back to the Neolithic era, and historians believe that weaving was actually invented at multiple times in different parts of the world. For thousands of years, this process, in spite of the enormous diversity of looms found across the globe, remained essentially the same: a weft thread is passed through rows of warp threads by means of a shuttle, a wooden piece carrying the spool of weft threads, in a back-and-forth movement from one edge to the other. This means the weaver must catch the shuttle as it passes from one hand to the other, which explains the width constraints of fabrics produced on early looms.
The industrial revolution would bring about considerable changes that would eventually overcome the slowness, width constraints, and inherent imperfections of this system.
Weaving techniques
Warp threads are wound parallelly onto a warp beam and threaded one by one through heddles (perforated rods). These heddles can be worked independently of each other (as is the case with jacquard looms), or attached in series to frames (or slats), and alternately raised or lowered depending to the weave.
Weaving looms
They fall into two categories:
- Shuttle looms
The oldest weaving loom was a shuttle loom. Today, there are still traditional looms, ribbon looms and flying shuttle looms, which can be manual or automatic.
Characteristics: the weft moves back and forth, the edge is clean, with no excess thickness and no fraying.
Use: selvedge quality is appreciated in items such as narrow textiles (scarves, ribbons, elastic bands, non-scratch labels), selvedge denim, or traditional fabrics, especially silk (scarves), or wool (kilts, throws). Thanks to their flexibility, they are also suitable for sampling.
- Shuttle-less looms
These are modern, automatic looms. They include projectile, water-jet, air-jet and rapier looms.
Characteristics: the weave is cut into sections of sufficient length to run from edge to edge. Edges are thusreinforced to prevent fraying.
Use: because of their speed of execution, these looms produce most of the fabrics found on the market.
The jacquard loom exists with or without a shuttle. The jacquard mechanism is a system in which each warp thread can be individually raised or lowered, unlike systems with shafts (or frames), which control a large number of heddles at once.
Characteristics: For each pass, a perforated card controls the lifting of each warp thread.
Use: This system makes it possible to create woven motifs through any play on weaves, regardless of their complexity (see section on weaves).
Choice of yarns
Because of their unique roles in the weaving process, the yarns used to make up the warp are different from those constituting the weft.
- Warp threads:
Characteristics: to execute their function, these threads need to be fine, smooth and strong, as they are constantly subject to friction from the reed that beats down the weft thread with each pass.
Use: They run parallel to the selvedge and form the crosswise threads.
- Weft (or pick) threads:
Characteristics: these are subject to less stress than the warp threads. They can be irregular and highly fancy. The weaving speed depends on the thickness of the weft thread, which is why we frequently find fabrics where the weft is thicker than the warp (such as poplin).
Use: these run perpendicular to the warp and constitute the crosswise threads.
Thread Count
A weave’s thread count corresponds to its density, which is a ratio between the size of the yarn (its yarn numbering) and the number of yarns per square centimeter or square inch, in the warp and in the weft.
There are different ways to measure yarn numbering: “metric count” for spun yarns, and “Decitex/dtex” for filaments.
A low thread count with fine yarns produces soft, airy, delicate fabrics such as mousseline or cotton organdy.
A low thread count with coarse yarns produces a supple, opaque fabric and gives free rein to fantasy yarns, such as tweeds or soft basket-weaves.
A high thread count with fine yarns produces dense, opaque fabrics, such as fluid satins or ottomans.
A high thread count with thick yarns produces strong fabrics that are often heavy and stiff, such as double faces, diagonals or thick satins.