BUILDING ACTION IN SOAPS

Competitive binding of calcium ions by combinations of soap and deterg ent builders viz., sodium tripolyphosphate (STPP), tetrasodium pyropho sphate (TSPP) and ethylene diamine tetraacetic acid (EDTA) was studied in model systems as well in formulated toilet soaps. Studies on model systems indicated that the distribution of calcium ions between the s oap and builder is a function of the ratio of the concentration of the soap and builder. During the initial stages of the interaction of cal cium ions with the combinations of soap and builder, formation of Ca-b uilder complex predominates while over longer intervals of time (under ''equilibrium conditions'') calcium soap formation takes over.