Eighteen cottons have been compared by processing under constant conditions and determining the yarn quality and breakage rates incurred by rotor - and ring - spinning. The cottons were of nominally the same properties other than differing in Micronaire level, the general degree of cleanliness and the level of bark within the cotton.

Analyses of the resultant data showed that cottons described as having a heavy bark content performed worst of all, yet there were only small differences between cottons assessed to have either 'zero' or 'medium' levels of bark. The difference in bark levels between 'medium' and 'heavy' categories was found within bales which had received one grade reduction for bark. Shirley Non-lint Content was a fair indicator of opening and carding waste, but a poor estimator of spinning performance and yarn quality.