Dyeing Process by Jigger Dyeing Machine with limitation

Dyeing Process 

The dyeing process on jigger is regarded as a series of intermittent padding operation followed by dwelling periods on the main roller , during which the dyeing action and diffusion takes place.

In the dyeing on jigger machines the cloth revolves on two main rollers , The open-width fabric passes from one roller through the dye bath at the bottom of the machine and then onto a driven take-up roller on the other side. When all the fabric has passed through the bath, the direction is reversed. Each passage is called an end. Dyeing always involves an even number of ends. The dye bath has one or more guide rollers , around which the cloth travels , and during this immersion achieves the desired contact with the dye liquor. During this passage the fabric picks up adequate quantity of dye liquor , excess of which is drained out but still a good quantity is held in the fabric . During rotation of rollers this dye penetrates and diffuse into the fabric. The real dyeing takes place not in the dye liquor but when the cloth is on the rollers, since only a very small length of fabric is in the dyebath and major part is on the rollers . Therefore the speed of cloth during immersion in dye liquor has a very little effect on percentage of shade produced.

Some critical problems related to the conventional jigger dyeing machines ( which are minimized in the modern day machines) The major problems are side-to-centre color variations, called listing, and lengthways color variations, called ending.

The factors controlling the rate of dye absorption are

1. The amount of interstitial dye liquor retained in the interstices of the fabric weaves.
2. The exhaustion of the interstitial liquor in the dwell period between successive immersions.
3. The degree of interchange of liquor during one immersion (interchange factor).

Problems of Jigger dyeing

• Temperature control from side-to-side and end-to-end of the roll
• Tension control from end-to-end
• Constant speed control from end-to-end
• Prevention of creases
• Prevention of air

Limitations of Jigger Dyeing

1.     Jigs exert considerable lengthwise tension on the fabric and are more suitable for the dyeing of woven than knitted fabrics.

2.     In textile preparation due to the swelling and dissolution of size, which makes the fabric slippery and unstable in roll form.

3.     The low liquor ratio makes washing-off difficult.

4.     There is little mechanical action in a jig machine and it is less suitable where vigorous scouring is required before dyeing.

5.     Moiré effects or water marks may arise on some acetate and nylon fabrics because of pressure flattening the structure of the rolled fabric.