COLOURED STITCH DESIGNS IN WEFT KNITTING

Colour is one of the five ingredients of fashion, the other four are style, silhouette, texture and pattern. Ornamentation for design purposes may be introduced at the fibre, yarn, or dyeing and finishing stage and knitting stage. Apart from different colours, it may take the form of sculptured or surface interest. In fibre form it may include a variation of fibre diameter, length, cross-section, dye uptake, shrinkage, or elastic properties. In yarn form it can include fancy twist and novelty yarns, as well as the combined use of yarns produced by different spinning or texturing processes.

The dyeing process may occur at any point in manufacturing from fibre to finished article. The finishing process may also utilise heat or chemically-derived shaping. Finally, printing can introduce colour designs onto plain colour surfaces, whilst embroidery stitching may provide relief designs in one or more colours.

The finishing process can completely transform the appearance of a relatively uninteresting structure, either as an overall effect or on a selected parts. The knitting of stitch designs always involves a loss of productivity compared with the knitting of plain, non-patterned structures. Machine speeds are lower, less feeds can generally be accommodated, efficiency is less, design changes are time-consuming and dependent upon technique and machine type, and, in many cases, more than one feeder course is required to knit each pattern row.

At the knitting stage four techniques may be employed to produce designs in coloured stitches. These are horizontal striping, plating, and individual jacquard stitch selection.

Horizontal striping provides the facility to select one from several coloured yarns at a machine feed position. Even without striping selection facilities, by careful arrangement of the packages of coloured yarns on a large diameter, multi-feeder machine, an elaborate sequence of stripes repeated at each machine revolution, is obtained.

Intarsia is a special method of producing designs in knitted loops that form self-contained areas of pure colours. Unequalled colour definition is achieved, with a large number of colours and no adverse effect on the physical properties of the structure such as reduction of extensibility.

Plating is widely used for single jersey, plush, float and interlock fleecy. However, with the exception of embroidery motif plating, the use of coloured yarns to produce plated designs has diminished in weft knitting. Plating requires great precision and offers limited colour choice compared with the improved facilities offered by jacquard knit and miss needle selection of coloured stitches.

In reverse plating, two yarns (usually of contrasting colour) change their positions at the needle head by controlled movement of specially-shaped sinkers or yarn feed guides.

In sectional plating (straight bar frames), the ground yarn knits continuously across the full width whilst the plating carrier tubes, set lower into the needles, supply yarn in a reciprocating movement to a particular group of needles, so that the colour shows on the face.

Individual stitch selection is the most versatile and widely-employed method of knitting designs in colour, or different types of stitches in self-colour. It is based on the relative positioning of an element during a knitting cycle determining which stitch, from a choice of two or more, is produced in its corresponding wale at a particular feeder course of a machine revolution or traverse.

Date: 2015-12-11; view: 1029