In a spinning mill quite often one has to spin yarns from mixings of two or more cottons. Results from an experiment vouch that it is indeed feasible to estimate the CSP of yarn from a mixing of cottons. In this experiment we carried out spinnings of two cottons, one short and coarse, and the other long and fine, in isolation as well as in mixings containing varying proportions of the two. We calculated the fibre-test data for any mixing by taking the weighted average of the corresponding test-values of the individual components in the mixing. To estimate the CSP of the five yarns, we used the earlier ATIRA-data expressions for F2, and F₃  and Bogdan’s expression for F4, and determined, by regression, only the numerical constants in the expression for F1. The values of these constants were respectively, l =7.8574, and m =-1.9529. For each of the five yarns the CS estimate is very close to the experimental values –Table I – 9 - i.

This is not surprising: many authors have offered experimental proof to establish that the mixing CSP is nothing but the weighted average CSP of the component cottons.

In 1936-37 Dunkerly (10, 11) established this fact by four investigations. In one he used two Egyptian cottons that had CSP of 3185 and 1870, and spun them individually, and in mixings of the two in proportions of 95:5, 85:15, 66:34, and so on. In the second he used cottons that varied in CSP from 2570 to 1760; in the third from 3130 to 1818; and in the fourth 2147 to 2137.

In 1959 Louis Fiori and Sands (12) carried out an investigation with two cottons identical in all respects, but having micronaire of 3.2 and 6.2 respectively. They blended the two cottons to yield a micronaire of 4.1. They, then, compared the performance of the resulting yarn with that of a yarn spun from a single cotton of micronaire 4.0, and having all other fibre characteristics equal to those of the blend. They spun yarns of NE 14, 21 and 36. They concluded that the twist-strength curves for yarns from the blended and control cottons are similar in all respects, in spite of the fact that the blended cotton contained fibres varying extremely in fineness. They also subjected the yarns to loom operations without weft insertion. They concluded that the blended-cotton yarn could withstand the stresses of post-spinning operations as well as the control cotton.

In 1972 Simpson and Fiori (13), and Jack Simpson, Louis Fiori, Audrey V. Castillon and Hershel W. Little (14) offered experimental data to support the conclusion that the mixing-yarn CSP is the weighted average of the CSP values of the individual cottons.

Table I – 9 -i : Application Of Equation To Estimate
CSP Of Yarns From Mixings Of Disparate Cottons
OBS: experimentally observed; ERR: error