Effect of underwater flexibility of a soiled cloth on the detergency of automatic washing machines

To determine the conditions of Terg-O-Tometer (a laboratory-scale test washing machine) that match the cleaning performance in real households, this study compares the detergency performances of a vertical washing machine and a Terg-O-Tometer on cotton and chemical fibers. Consistent with previous studies, the detergency of the Terg-O-Tometer matched that of the vertical washing machine at a rotation speed of 100 rpm for cotton cloth. However, when tested on polyester/cotton blend cloth, the matching rotation speed was 40-80 rpm, depending on the dirt on the fibers. These disparate results are attributed to differences in the frictional force between the cloths generated in the vertical washing machine and Terg-O-Tometer, and to differences in the underwater flexibilities of cotton soiled cloth and polyester/cotton blend cloth.