Some factors in the measurement of the suspending power of aqueous detergent/fabric systems

Summary The variability associated with the usual methods for measuring the suspending power of aqueous detergent solutions used to remove soil from textile fibers is pointed out, and a modified method, using multiple washes with very low concentrations of soil, is proposed. Two commonly used artificial soils are compared. Micronex, a typical fine particle carbon black, appears to give data in reasonable accord with practical experience while Aquadag, a suspension of graphite particles, tends to magnify some effects and therefore is more useful for specific tests. Aquadag is found to be highly dispersed in dilute aqueous suspension while Micronex (as well as other carbon blacks) forms relatively large aggregates in water. These aggregates are partially dispersed by vigorous agitation in a Waring Blendor but are more completely dispersed by rotation in the Launder‐Ometer in the presence of fabric, yarn, or fiber of cotton or other textile material. The influence of hard water and of other inorganic salts on suspending power data is discussed. The need for careful selection of type of soil and fabric and for careful interpretation of data is stressed.