Detergency Study: Comparison of the Distribution of Natural Residual Soils After Laundering with a Variety of Detergent Products

Abstract

Five commercial laundry detergents were evaluated using natural soil obtained from facial wipes. The largest observed difference between products was in their removal of particulate soil from the yarn surfaces. The effectiveness of particulate soil removal was related to the surfactant/builder system, with the phosphate built, anionic powdered detergent being the most effective, and the built liquids being more effective than the unbuilt liquid detergents. For all detergent products tested, electron beam x-ray mi croanalysis indicated that the largest percentage of residual oil was located in the interfiber capillaries of the yarn structure, followed by the secondary walls, the lumen, and the crenulation of cotton fibers. Little or no oil was observed in the interior of polyester. The large variation in soil level between facial wipes prepared by different panelists had an effect on the concentration of the oil within the fibrous structures. The type of laundry detergent used also influenced the concentration of residual oily soil found in selected locations within and around the cotton and polyester fibers. Fiber surfaces retained less oil when the fabrics were laundered with the powdered detergents than when washed with the liquid detergents, but there were no differences in performance between the liquid and powdered detergents in removing oil from the lumen, crenulation, or secondary walls of cotton. The phosphate built powdered de tergent with anionic surfactants removed oily and particulate soil from yam surfaces more completely than the carbonate built powdered detergent with nonionic surfac tants. In comparison, the distribution of residual oil within the yarn structure was the same after laundering with the two powdered detergents. The citrate built liquid had higher concentrations of residual oil in the crenulation of the cotton fiber and on the fiber surfaces than the other liquid detergents. Since the differences between products were small, it appears that the factors limiting the detergency of oil from fabric structures are the same for all the detergent products evaluated.