A Comparative Study of Sonic and Mechanical Home Washers

Abstract

FOR CENTURIES, textile fabrics have been laundered by the application of some type of mechanical action in a water medium. Mechanical action has varied from pounding fabrics with rocks in streams to oscillating or twirling fabrics in the modern automatic home or commercial laundry equipment.The need for providing some means of bringing the detergent solution and the cloth undergoing laundering into more intimate and efficient contact than that provided by gross mechanical action, with a greater preservation of the strength of the fabric, has encouraged research workers to study other methods, such as sending acoustical waves through the detergent medium, with results which have given promise of having practical applications.Schilling, Rudnick, Allen, Mack, and Sherrill [2] began studies in this field in 1947, using a highfrequency siren, equipment described by Allen and Rudnick ( 1 ] . These authors were the first to publish numerical data in this country on the subject of sonic and ultrasonic waves as a means of removing soil from textile fabrics. In the work of these in-vestigators, the amount of detergent used was that found previously to be optimum in studies with power laundry machinery. Data were presented to show that 1,000 min. of total washing time and 50 changes of soap and water produced about 80% as much soil removal as 60 min. of exposure in a watersoap medium to an intense sound beam. Moreover, the 60-min. treatment with the siren gave as good or better soil removal than that obtained by three excellent commercial laundries, each using 50 complete washing cycles and a total washing time of 3,500 min.In the spring of 1950, a laboratory model of a small home sonic washing device invented in Australia became available for study in the Ellen H. Richards Institute. The device operated at a considerably lower frequency than was used in the laboratory sonic and ultrasonic studies previously begun in these laboratories, and was described by the inventor as being equal to or superior to the most widely used mechanical home washing machines in soil removal.The possibility of strength conservation and resistance to dimensional change in textile fabrics by the use of acoustical waves suggested a comparative study of these factors, in addition to an evaluation of soil removal with the new instrument in comparison with customary methods of washing. * This is the first report on the sonic washing of rayon fabrics, sponsored by American Viscose Corporation through