Presents a study of the capability of commercial dishwashers to remove bacteria from various kinds of service plates. Gives an account of preliminary research on the bacterial cleanability of eating surfaces of different materials by two radiological procedures--(1) radiological count, and (2) autoradiographic measurement. Among the factors studies were--(1) type of material, (2) condition of surface, (3) effect of different types of organisms, (4) effect of various types of organic soils, (5) effect of repeated washings, and (6) effect of soil build-up by repeated soiling and washing. Different eating surfaces studied were dinner plates made of--(1) china, (2) plastic, (3) glass, (4) stainless steel, and (5) aluminum. Experimental procedures and results are given. (RH)