This is a very serious problem in the jigger dyeing of woven fabrics of wider width.
This problem gets much serious when the fabric is dyed in a dark shade. When the wider width woven fabric is dyed on a jigger dyeing machine, there is always a possibility of resulting shade difference between the centre and selvedge of the fabric.
This problem is mainly reflected in dark shades. This is a very serious drawback of the jigger dyeing process. It is not a problem with the jigger dyeing machine actually. But this problem reflects in the fabric when wider width woven fabric is dyed by using the jigger dyeing process.
Now a question may arise in your mind why does this problem appear. The simple answer to this question is due to an unavoidable weaving defect present in the grey fabric. What is that unavoidable weaving defect? That unavoidable weaving defect is excessive bowing present in the grey fabric.
Now you can ask me how this bowing does result in the form of shade difference between centre and selvedge during the jigger dyeing process.
Before explaining the reason for this problem, it is necessary to know the working method of the jigger dyeing machine.
A jigger dyeing machine is a very simple machine. It basically has two batching rollers and an open colour tank. The fabric is loaded on one roller. This fabric transfers onto the second roller after the fabric passes through the colour tank. The transfer of fabric from one to another roller continues till the completion of the full dyeing process.
When the fabric transfer takes place, the fabric passes under sufficient tension. This fabric tension acts as squeezing pressure on the fabric and helps to squeeze the water from the fabric continuously.
How does the squeezing action take place? When the fabric transfer takes place, one layer of fabric wraps on the other fabric layer. Here fabric tension comes out in the play and presses the fabric. Thus the maximum water is eliminated continuously throughout the full process.
Now we come on the fabric bowing. The bowing of the fabric creates a difference in the length between the centre and selvedge in the fabric.
If the fabric has bowed in it and when it wraps on the batching roller of the jigger machine, the fabric wraps slight loose on the roller at both the selvedge side. This loose wrapping of the fabric helps to decrease the squeezing pressure at both the selvedge. Thus the fabric holds more water at both the selvedge sides than the centre. This extra water in the fabric at the selvedge side results in the form of a more dark shade than the centre fabric.
The degree of shade difference between centre and selvedge in the dyed fabric completely depends upon the degree of bowing present in the grey fabric.
The less bowing in the fabric means less difference between centre and selvedge after dyeing.
The C. S. may also appear in smaller width fabric. It appears on the side only. How does it happen? It may happen if the fabric has been woven on wider width loom in two parts.