A new method for determination of the relative colour strength of dye based on new colour depth formula. Part II: application to different batches of colourant

Abstract

As a standard for the evaluation of relative colour strength (RCS) of dye, AATCC EP‐6 (SWL [K/S], SUM, and WSUM) has been widely used, while its limitations are often overlooked by people. In Part I of this study, the new method Yangn (CSV1, CSV2, and CSV3) for the determination of RCS were proposed, Yangn and AATCC EP‐6 were tested using the different types of disperse dyes that have approximate hues. However, the calculations of RCS for the same dyes produced in different batches were also necessary, therefore, this article (Part II) focuses on it. The HL series dyes produced in 2020 and 2021 were used to test Yangn and AATCC EP‐6. The same results as Part I, the colour strength values calculated by SWL, SUM, and WSUM were inconsistent. Furthermore, in the methods of AATCC EP‐6, the colour strength values calculated by WSUM should be at least rounded to four decimal places to avoid false calculation; the value of Yangn only need to be rounded to two decimal places. For the RCS of the same dyes produced in different batches, the methods of AATCC EP‐6 and Yangn were relatively the same under different dyeing concentrations. The coefficient of variation (CV) values of Yangn were < 1.3%, the CV values of AATCC EP‐6 were < 2%. Therefore, according to the consistency of the calculation, the CV values and the dependence on the concentration, the new methods of Yangn were superior to the traditional methods.