The current expansion of the worldwide market for cotton has opened up many possibilities for the spinning mill. Spinning mills now have many options in the raw materials they purchase for producing yarn. This expansion in the availability of raw material has helped in reducing costs and improving yarn quality and spinning efficiency. Unfortunately this situation has also presented some new challenges for the spinning managers and cotton buyers. Traditionally purchased cottons had well established seed varieties and growing regions. This meant that with an average control of micronaire they had few problems with the dying and finishing of cotton fabrics.

Over the past two years we have seen a rapid increase of the problems with dying and fabric finishing. This is especially evident in the claims and rejects of 100% cotton knitted fabrics for barre'. Claims and rejects can easily wipe out any savings in raw material costs obtained by purchasing cotton from several international sources. Figure 1 is a classic example of the problems related to mixing cottons of similar micronaire but from different growing regions and seed varieties. Many spinning mills are under the impression that all upland seed varieties mature the same as related to the micronaire. Unfortunately what they discover is that cottons with similar micronaire that have different growing regions and seed varieties dye differently.

Controlling some of the basic fiber properties can give the spinning mill the information necessary to reduce and or eliminate the recurring problems of barre'. Mill experience and trials have given us the necessary information to set up guidelines for controlling the fiber properties that influence the dyability of cotton yarns in knitted fabrics. There are several mechanical causes of fabric barre' that are associated with the spinning and sliver preparation processes in the spinning mill. Figure 2 highlights the major causes of barre' showing the major influence is from the fiber. While mechanical differences and variations in yarn count, twist and hairiness can also be a cause of the barre' effect the single largest cause lies in the variation in fiber properties. Figure 3 shows the fiber properties that have an major influence in the causes of barre'. Micronaire, maturity/fineness and fluorescence all play a major roll in the consistent dying and finishing of knitted fabric.