Abstract The aim of this work is to determine the influence of certain clay micro particles added to detergent formulation to act as builders in removal of impurities (detersive power) during the washing of a standard cotton fabric (EMPA), and also to determine the whiteness of the fabric and its softness after washing. Sepiolite was used separately and together with bentonite, in the form of micro particles. Bentonite is held to have a softening effect on cotton. A whitener was added to the detergent formulations to compensate for a possible effect of diminished whiteness in the washed fabric. Scanning electron microscope images of the fibres were taken to show deposition of the builders on the fabric. A non-toxic microemulsified solvent, dimethylsulfoxide (DMS), suitably microdispersed with use of an amphoteric surfactant as emulsifier, was added to improve the performance of the detergent formulations used, notably enhancing the detergency obtained in the presence of the clay microparticles tested.