Knitted Fabrics Flashcards
Knitted fabrics
Knitted fabrics are cheaper to produce than woven fabrics. They are crease resistant, light in weight and have a natural give or stretch, making them comfortable to wear. This, as well as the availability of filament and textured filament yarns, has led to an increase in the popularity of knitted garments. Whereas in 1963, only 24% of clothing fabrics were knits, they accounted for nearly 50% by 1978.
In knitting we refer to the rows of stitches running in vertical columns along the lengthwise direction of the fabrics as wales. This corresponds to the warp of woven fabrics. Crosswise rows of stitches are called courses. This corresponds to the filling or weft of woven goods.
Weft knitting
Weft knitting is similar to hand or domestic machine knitting. One yarn is passed from needle to needle, forming one course at a time. It is called weft knitting because the yarn moves from side to side as the weft yarn does during the weaving process. In industry, most weft knitting is done on machines that have needles arranged in a circle. The fabric is formed as a tube which can be slit to form a flat fabric. This is called circular or tubular knitting. The knitted tube is not always cut open; it can be used in a tubular form for T-shirts and socks and nylon stockings (hosiery). Weft knitting can also be produced on a flatbed machine.
Weft knitting can be classified into four basic stitches:
knit, purl, miss and tuck. The latter two are produced by changing the way the yarn loops interlock.
Knit stitch
Knit or plain stitch resembles what hand knitters’ call stocking stitch. The crown of the loop is at the back of the fabric. Consequently, each side of the knit exhibits a different type of structure. On the front side, all the courses have loops with the crown of the loop at the back (reverse loops) and the legs form a V pattern in the wales. On the reverse side, all the courses have loops with the crown of the loop at the front (face loops) and the courses form a wave pattern. The loops in all courses and wales are identical. If one does this stitch by hand, one would knit one row plain and one row purl. It is the stitch mostly used for T-shirt fabric. A fabric in knit stitch curls and shows more stretch in the width direction. It can be easily unravelled from the edge knitted last or from the edge knitted first.
Purl stitch
Purl, or reverse stich, looks somewhat like the reverse side of plain stitch. In purl knits the courses are alternately made of face and reverse loops. In one course the loops have the crown of the loop at the front (face loops), while in the next course the loops have the crown of the loop at the back (reverse loops). Each wale is made up of face and reverse loops. In hand knitting, this is achieved by knitting every row plain, and is called garter stitch. Purl knit is often used for babywear. The front and the back of the fabric look the same. It is slightly thicker than a fabric in knit stitch. It does not curl and exhibits good stretch in all directions. It can also be unravelled easily.
Miss stitch
In miss or float stitch, the stitch is not actually formed, but the yarn floats at the back of the fabric. The needle is not pushed forward at all the yarn is not hooked by the needle, but the old loop is retained with the new yarn just “floating” across it.
Tuck stitch
In tuck stitch, the needle is pushed just far enough to hook the yarn but not to knit off the previous stitch. Both the previous stitch and the new loop remain on the needle.
Weft-knit fabrics have the following characteristics:
They can either be fully fashioned or cut and sewn like any woven fabric.
A run can form in the lengthwise (wale) direction if a yarn breaks.
They have good stretch, especially in the course direction.
They can be manufactured in a wide variety of constructions and patterns.
They are crease-resistant.
Plain, jersey or single, knits
Plain or single knits are made on one set of needles, on a circular or a flatbed machine. They are not dimensionally as stable as knits produced on two sets of needles. A run occurs very easily in a plain knit. Production rates are high. The fabrics are used for sweaters, t-shirts, seamless socks, pantyhose, underwear, piece goods and fully fashioned garments.
Purl knits
Purl fabrics have been described under the purl stitch. They do not curl and have considerable stretch, particularly in the wale direction. Purl knits are slow and costly to produce. The purl structure is often used as a way to introduce pattern to plain knitting. Because of their extension, they are commonly used for infant’s and children’s wear.
Rib knits
Rib-knit fabrics have lengthwise ribs. They need two sets of needles, arranged in a flatbed formation or in a circle. A rib knit can stretch considerably in a crosswise (horizontal) direction. They also tend to be warm. Production rates are slower than for single or purl knits, and rib knits are more costly because of the increased fabric weight (more yarns are used per unit area). Because of their stretch and close fit, they are used at the lower edges of sweaters or sleeves, and at necklines, as well as for socks, knitted hats, t-shirts, sweaters, piece goods and garments.
Cardigan
Cardigan stitch (often called fisherman’s rib in South Africa) is a variation of rib knitting which consists of a tuck stitch on one or both sides of the fabric. It produces greater width than ordinary rib stitches from the same number of needles. Fabrics are used for garments and sometimes piece goods.
Interlock/double jersey
The interlock knit is another variation of the rib knit. It resembles two separate 1 X 1 rib fabrics that are interknitted. The fabrics (double jersey or double knits) are thicker and heavier than regular rib fabrics of the same gauge (gauge is the fineness of a knit fabric). They have better stability, are easier to sew and do not tend to curl at the edges. Double jersey is used for outerwear, often using wool or acrylic fibres, and underwear, using cotton fibres. Jacquard knits, Ponte di Roma and knitted pile fabrics are other variations of double knits.
Warp knitting
In warp knitting, the loops are formed in a warp wise direction. Each needle is supplied with its own yarn. The loops are interlocked with the loops on either side. The fabric consists of vertical chains of loops which are connected sideways. Warp knitting is manufactured rapidly and in great quantities. The fabric is flat and has straight side edges. Warp knitting can be classified according to the type of equipment used. Types of warp knit fabrics are discussed in the following section.
There are two main kinds of warp knit fabrics:
Tricot and Raschel.
Tricot fabrics
A larger variety of tricot fabrics such as plain, satin and brushed tricot are produced. Tricot fabrics are soft, crease-resistant, run-resistant and elastic, do not fray, and have good draping properties. They are predominantly used for panties, petticoats, sleepwear, dresses and linings laminated to other fabrics.
