The fabric structure is the fundamental unit that controls all properties of weft knitted fabrics. S Senthil Kumar discusses derivatives of structures in weft knitted fabrics, besides the properties, requirements and application of various weft knit structures.

Knit fabrics are popular for their feeling and extensibility, with weft knit fabrics being widely used. From the production perspective, it is easy to produce knit fabrics than woven. Structure is an important criterion for any material, especially for fabrics. So, to increase fabric durability and dimensional stability, fabric structures and properties play a vital role. Among all types of weft knit fabrics, the single jersey fabric is most popular. Knitted fabrics have special characteristics that make them suitable for creating a wide range of garments and accessories like tights, gloves, underwear and other close-fitting garments. Their properties can be changed with the use of various structures and stitch length.

Stitch notations

The weft knitted structural units can be represented using the following methods:

a) Line diagram

b) Symbolic notation on graph paper

c) Schematic or diagrammatic notation

A line diagram representation is easily understood by beginners, but it is comparatively difficult to produce, particularly for complex designs. Symbolic notations on graph papers are widely used for the representation of knitted structures. Any type of loop or knitted structure can be represented on a graph paper with the help of some symbol. There are a large number of horizontal and vertical lines at equal distance which divide the paper into large number of squares. Each square is used to represent one loop. The horizontal rows are used as courses, whereas the vertical columns indicate the wales in the knitted structure. The presence or absence of some particular symbol in a square indicates the various types of loops or stitches.



Characteristics and properties of rib structure

  •          Rib fabrics are double-faced structures as well as balanced structures.

  •         Both face loops and back loops are visible on both the sides of the fabric, and fabric has identical appearance on face and at back.

  •          Both face loops and back loops are visible on both the sides of the fabric, and fabric has identical appearance on face and at back.

  •          Fabric surface is vertically corrugated or ribbed.

  •          Fabric is much thicker, usually double, than single jersey fabric.

  •          Fabric surface is rough or harsh in feel.

  •          Fabric does not curl at the free edges.

  •          Fabric can easily be unroved from the end last knitted.

  •        Fabric has good extensibility in length direction, but the width-wise extensibility and the recovery are much higher than single jersey fabric.

Needles in the two beds are not face to face but needles in one bed are in between the needles of the other bed so that they do not touch while raised for clearing.


Full cardigan

For a full cardigan or polka rib, the first course is knitted with face, and tuck loop on second course with a tuck, followed by a reverse loop. It is a therefore a balanced structure.

End Uses

Rib fabric is suitable for collars, handcuffs, waistbands, warm outerwear, underwear, socks and swimwear.

Interlock Structure


Characteristics and properties of interlock structure

  •          Fabrics are dimensionally stable, heavy and costly.

  •          Machines have two beds. Machines may be flat or circular, but generally circular.

  •          Minimum two yarns are needed to produce a fabric.

  •          Fabric has double faced as well as very stable structure.

  •          Fabric surface is smooth.

  •          Fabric is equally thicker to rib but much more compact.

  •          Fabric neither curls nor ladders.

End uses

Interlock fabrics are suitable for underwear, trouser suits, shirts and sportswear.

Derivatives of interlock structure

  •          Eight lock,

  •          Single pique,

  •          Ponte- di-Roma,

  •          Ottoman rib,

  •          Bourrelet,

  •          Texi pique,

  •          Pin tuck,


Purl Structure


Characteristics and properties of purl structure

  •          Alternative courses are made of all face loops and all back loops. As a result, each wale is made of face loop and back loop in an alternative order.

  •          Fabric has horizontal corrugation or rib appearance on the surfaces, i.e. opposite to rib fabric.

  •          Fabric is reversible in appearance and has soft handle.

  •          Fabric has very high extensibility in length direction, making it suitable for kidswear.

  •          Fabric does not curl at the edges because of alternate face and back loop courses.

  •          Fabric thickness is theoretically double to that of a plain knit.


End Uses

Purl fabric is suitable for children's clothing, knitwear, heavy outerwear, golf sweaters and sportswear.


1. Sadhan Chandra Ray, Fundamentals and Advances in Knitting, Woodhead Publishing.

2. Md. Azharul Islam, Effect of Wale wise Increasing of Tuck And Miss Loops on Bursting Strength of Single Jersey Fabric at Grey and Finish State, IJRET, ISSN: 2319-1163.

3. David J Spencer, Knitting Technology, Woodhead Publishing.

4. KB.Pujari, Weft Knitted Constructions, IIT Delhi.

5. Textile Study Center.

6. D. B. Ajgaonkar, Knitting Technology, Universal Publishing.

About author: S Senthil Kumar is Fabric Technologist at Young Brand Apparel Pvt Ltd, Chennai.


Graphical notation of loop





German notation of loop (DIN 62050)


Characteristics and properties of single jersey

  •          Plain jersey is produced by a single set of needles, drawing the loops away from the technical back and towards the technical face side of the fabric.

  •          The technical face is smooth, with the side limbs of the needle loops having the appearance of columns of Vs in the   wales.

On the technical back, the heads of the needle loops and the bases of the sinker loops form columns of interlocking semi-circles.

  •          The single jersey is a weft knitted fabric formed with face knit stitches on the face side, and back knit stitches on the rear.

  •          The fabric has good extensibility in both length and a width direction, but width-wise extensibility is usually much higher than length-wise extensibility.

  •          The fabric curls at the free edges on flat surface-towards the front at the upper and lower edges, and towards the back at left and right edges.

  •          The fabric shrinks in width/circumference, and the extent of shrinkage is about in the range of 25-40 per cent.

  •          The fabric thickness is approximately twice the diameter of the yarn used.

  •          Properties like rigidity, air permeability, bursting strength and GSM of the fabric change with change in loop length.

  •          Yarn /course can be unroved from start and end of knitting.


2.2. End uses

Plain knit structures are used for basic t-shirts (men's and ladies), undergarments , men's vests, ladies' hosiery, fully fashioned knitwear, etc.

Derivatives of plain knit (Single Jersey)

Structural modifications are used to a great extent in designing plain knit structures by modifying the order of knitting. The plain knit structures can be modified with the following alternatives:

  •          Knit and float,

  •          Knit and tuck,

  •          Knit, float and tuck.

Tuck loop

If -while rising -the needle reaches such a height that the old loop is not cleared but needle hook can catch a new yarn during the downward movement, then the old loop is not cast off but retained in the hook and a new loop too is formed. This situation is called tucking, and the new loop is called tuck loop. The tuck loop tends to be wider than equivalent plain loop, and it can be used to increase the width of the fabric. But during tucking, the held loop is stretched as a result when the same is cast off and allowed to relax; it shrinks more, causing more shrinkage of the fabric in the length direction. It makes the fabric more compact and offers better dimensional stability and shape retention.


Characteristics of the tuck stitch

The tuck stitch exhibits two free arms that spread away from the concerned wale line. The neighbouring wale lines would therefore be pushed away from their normal location in the resultant fabric. This results in localised openings on the two sides of a tuck stitch and in reduction in number of wales per unit length. Effectively the resultant fabric becomes more porous and wider. Tuck stitch makes the fabric wider, more porous and thicker.



Float loop (Miss loop)

If -while rising-the needle reaches such a height that neither the old loop can be cleared nor the needle hook catch new yarn during downward movement, then the old loop is not cast off but retained in the hook as well, as no new loop is formed. This situation is called floating. The yarn passes under the needle and remains straight between the neighbouring loops. The straight yarn connecting the two nearest loops knitted from is called float or miss loop. Float stitches also reduce the width-wise elasticity and improves the dimensional stability.


Characteristics of the float stitch

  •          Imparts additional rigidity to the fabric along the course direction.

  •          The pull in the adjacent wale lines close together, tending to make the fabric narrower.

  •          The float also tends to make the fabric appear thinner at the affected zones.

  •          A float is, however, a loose yarn segment on the technical back side of a single jersey fabric and is therefore prone to snagging caused by any sharp object or abrasive surface.

  •         Float stitch makes the fabric narrower, thinner due to minimum yarn used in construction and more rigid in the course direction.

  •          Fabric is flimsy and less rigid compared to others.

  •          Less extensible than either knitted or tucked structure.


2x2 Rib structure (Double jersey)


Derivatives of rib structure

  •          Half cardigan,

  •          Milano rib,

  •          French pique,

  •          Swiss pique.




Half cardigan

In half cardigan or royal rib on one course, a 1x1 rib is produced, and on another course a tuck loop and a reverse loop are produced. It is therefore an unbalanced structure.