Cotton Knitwear as a Carrier of Specific Stains for Evaluation of Temperature-Specific Behavior of Detergents

Washing performance depends on the specific interactions between textiles, stains, detergents, mechanical action, temperature, and time. Its evaluation therefore requires a fundamental and practical understanding of the effects of the washing parameters, the type of soiling, and the tendency of the textiles to stain. Due to the complexity of these interactions, the evaluation of stain removal requires specific types of textiles, stains, and detergents. In this study, the temperature-specific behavior of detergents was studied in the washing process of cotton knitwear with a blank spot and 15 stains of different origin and composition at 60 °C and 90 °C. Despite the labeled composition of detergents, the detergent ingredients, surfactants, and bleaching agents were analyzed by titration methods. The evaluation of the total washing performance (TWP) and specific washing performance (SWP) was carried out by measuring reflectance as a spectral parameter. A hierarchical cluster analysis was carried out to compare the specific effects of detergents at both temperatures. The analysis of the detergents revealed fluctuations in the content of the surfactants and bleach. Some detergents with a higher surfactant content (SAS) showed poorer performance in washing at 60 °C compared to detergents with a lower SAS content. The dendrogram showed subtle similarities and dissimilarities between the detergents, which contributed to clarification of the total wash performance at both temperatures. The results proved that the quantitative indicators of the proportions of certain ingredients in a detergent are not the only criteria for evaluating the quality of a particular detergent. All detergents investigated showed a temperature-specific behavior, which was reflected in an increased TWP at 90 °C, while some detergents selectively improved the SWP at 90 °C.