This is a very serious problem in jigger dyeing of woven fabrics of wider width.
This problem gets much serious when fabric is dyed in dark shade. When the wider width woven fabric is dyed on jigger dyeing machine, there is always a possibility of resulting shade difference between center and selvedge of the fabric.
This problem mainly reflected in dark shades. This is very serious drawback of jigger dyeing process. It is not a problem of jigger dyeing machine actually. But this problem reflects in the fabric when wider width woven fabric is dyed by using jigger dyeing process.
Now a question may arise in your mind why does this problem appear. The simple answer of 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 center and selvedge during jigger dyeing process.
Before explaining the reason of this problem, it is necessary to know the working method of jigger dyeing machine.
A jigger dyeing machine is a very simple machine. It basically has two batching rollers and open colour tank. The fabric is loaded on one roller. This fabric transfers onto the second roller after fabric passing through the colour tank. The transfer of fabric from one to another roller continues till the completion of 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 help to squeeze the water from fabric continuously.
How does the squeezing action take place. When the fabric transfer takes place, the one layer of fabric wraps on the other fabric layer. Here fabric tension comes out in the play and press 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 the difference in the length between center and selvedge in the fabric.
If the fabric has bowing in it and when it wraps on the batching roller of 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 center. This extra water in the fabric at selvedge side results in the form of more dark shade than the center fabric.
The degree of shade difference between center 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 center and selvedge after dyeing.
The C. S. may also appear in in smaller width fabric. It appears in on side only. How does it happens? It may happen if the fabric has been woven on wider width loom in two parts.