Constructing Fabrics
The most common method of combining yarns into cloth is weaving. This involves interlacing two sets of yarns at right angles by means of a loom. Cloth is also made by knitting where a succession of loops is made with each row interlocking with the one below it. This can be done by hand with knitting needles or by machine. Other methods are less common, such as crocheting and tatting, and will not be covered in this module. Non-woven fabrics are made directly from fibers so the yarn stage is omitted.
Woven fabrics are created on a loom with yarns strung tightly on the loom along the length of the fabric. The same or other types of yarns are woven back and forth across the fabric. The lengthwise grain is called the warp, and the crosswise grain is called the weft.
Woven fabrics tend to be quite stable with stretch only along the bias (the 45 degree angle between the lengthwise and crosswise grains). A woven fabric can only be made to stretch with the addition of a stretchy fibre such as elastane.
The most common types of weave are plain, twill and satin.
Plain weave is the simplest pattern with the weft running under one warp thread and over the next. A plain weave is only as strong as the yarns that it is woven from. It can be as light and fine as silk chiffon or as heavy as jute or hemp burlap.
Twill weave is created by the weft yarn passing over two warp yarns, then going under one, giving it the characteristic diagonal ridges that you can see on denim fabrics. It is inherently a stronger weave than the plain or satin weaves and is therefor used for fabrics that need to be durable such as denim and gabardine. A variation of the twill weave is the herringbone weave, where the direction of the diagonal changes back and forth, creating a zigzag pattern.
Satin weave is a shiny and luxurious fabric and can be made from lustrous fibres like silk, acetate, polyester, or other filament fibres. In a satin weave, the weft threads pass over many warp yarns, creating long “floats” which add to the shine of the fabric, but also weaken the fabric as they tend to catch and pull. Cotton, or other staple yarns, that are woven with a satin weave are called sateen.
Pile weaves add an extra set of yarns that are looped or are cut as in terrycloth, corduroy or velvet. The loops in terry cloth add to the absorbency of the fabric, while the cut pile in velvets adds to the soft feel and lustrous appearance. Velvets are made from filament yarns, such as silk; a cut pile weave made from a staple fibre is called velveteen. If the cut pile is woven in columns, the result is corduroy.
Pattern weaves include complex jacquard weaves, brocades, damasks, and tapestries. The punch cards required to operate jacquard looms were the precursor to early computer technology.
Knit fabrics are created on a knitting machine, either in a tube or flat. In weft knitting, one continuous yarn is continuously looped through itself in rows, resulting in a fabric with varying degrees of stretch. A more complex kind of knitting is called warp knitting and uses multiple yarns.
Knits tend to be most stretchy in the crossgrain, but some have stretch also in the lengthwise grain, and are called 4-way stretch. The column of loops running down the face of a knit is called a wale, and a crosswise row is called a course.
Knits can be single knit (where the wrong side is easily distinguishable from the right side) in familiar fabrics such as jersey found in most T-shirts. Double knit uses two sets of needles, resulting in both sides being usable as the right side. Pile knits, like pile weaves, have extra yarns that are looped or cut, resulting in fabrics like velour, microsuede, sweatshirt fleece, and artificial fur.
Bonded fabrics are not woven or knit yarns, but are simply fibres that have been pressed together, much like how paper is made. This can be done using either heat, moisture and agitation, as in traditional wool felt, or needle punching, as in acrylic felt, or they can be spun bonded, as in a dryer sheet, tea bag, and non-woven interfacings.
Solutions can also be made into textiles. The solutions are not first made into filaments or yarns, but rather made directly into a film. The end product could be a shower curtain, plastic table cloth, or weed control fabric.