Method for creating knitted denim

The 1st step of the method involves dyeing the yarn with a dyestuff to obtain dyed yarn. Indigo dyeing as well as other dyeing i.e. reactive dyeing and sulphur dyeing can also be used for yarn dyeing of the fabric. The 2nd step involves knitting the foundation layer with grey/white yarn and front layer with dyed yarn to compose denim fabric. Here the front layer is tensely tautened in intermittence with a tensile force greater than the tensile force on the foundation layer to make the foundation layer have random knots. The next step involves washing of denim for creating fading effect if yarn dyeing is carried out using indigo and sulphur dye. Subsequently processes involved in finishing section like drying, compacting etc is carried out to achieve the best quality product.

Piece dyeing, cheese dyeing and rope dyeing are the conventional methods used for dyeing denim. One of the dyeing methods involved for the present experiment is rope-dyeing method for dyeing knitting yarn to improve fastness and even dispersion of the dyestuff. The rope dyeing is used to drench the knitting yarn into a tank for sopping dyestuff and then the excess dyestuff is removed by passing the knitting yarn through paired rollers as the excess dyestuff gets squeezed out and the process of drenching ad squeezing of yarn is repeated several times until the dyestuff gets properly attached to the knitting yarn. In case of indigo dyeing using rope-dyeing method each strand of yarn is dyed around the surface and thereby living the yarn with a white core. The strands of dyed yarn are evenly dispersed and wound onto a bobbin so as to avoid transversal or any discreteness in color during knitting and producing fabric.

In this experiment a circular weft knitting machine i.e a single jersey machine using the usual knit, tuck and miss cam is used to construct even twilling pattern on the fabric and perform a dual – plied denim including a foundation layer and a front layer on the fabric. The foundation layer is loosely knitted with variable tension/tensile force and a different stitch length than that of the front layer by adjusting the circular weft-knitting machine. Cam arrangements are set for creating terry twill effect and only twill effect on the fabric. The front layer is compactly constructed with high tension/ tensile force by adjusting the machine to a high-density program.

After tightening the front layer, the foundation layer is shrunk to create multiple knots on the foundation layer and thus denim is obtained. When the denim is used, the foundation layer having multiple knots serves as an outer surface to reveal the random knots in appearance. Correspondingly, the front layer serves as an inner surface. This pattern can also be achieved by using lycra yarn (acting in the front layer) along with the colored yarn so as to produce a compact structure by shrinking the inner layer thereby knitted denim is obtained.

Simultaneously a second experiment was conducted using knitting yarn dyed in sample dyeing machine using reactive dye, which offers excellent wash and light fastness properties. Also reactive dyeing is easier and cheap and its disability to produce faded denim fabric is alleviated by modern garment washing processes in which fading effects can be easily incorporated to finished fabric /apparel. Same parameter is maintained during knitting to produce knitted denim.

Total 6 kg fabric of two single jersey fabrics: Knit denim and Tuck denim were produced in a single jersey circular knitting machine with lycra attachment. The fabric produced has been passed through a stenter and compactor in order to heat set the fabric as well as the lycra. The fabric is then test in the best way and in the right condition.