Performance of tapping washing in comparison with hand washing and front-loading machine washing for knitted wool sweaters

Wool fiber is widely used for clothing in our daily life due to its excellent physical and mechanical properties. However, in the daily laundry process, wool products can shrink severely by strong mechanical action in a warm and moist environment due to the fiber surface scales. Aiming to overcome the difficulty of washing delicate clothes such as wool and silk, Panasonic Intellectual Property Management Co. Ltd. invented a new washing machine for delicate clothes, based on tapping actions. The washing performance of wool sweaters in tapping washing is compared with that of hand washing and gentle and normal machine washing. The results show that tapping washing always gives wool sweaters the best appearance, dimensional stability and mechanical property up to 10 washing cycles. The changes in appearance and mechanical properties of wool sweaters are mainly due to the rate of felting shrinkage. By comparing the magnitude, duration, number of mechanical actions and direction of the forces acting on the fabric in tapping washing, hand washing and gentle machine washing, it can be concluded that the direction of forces acting on the fabric has a significant effect on wool fabric felting shrinkage, and unidirectional force has less effect on felting shrinkage than multidirectional forces. Tapping washing can give the lowest felting rate to wool samples because the forces in tapping washing on all parts of the fabric have a similar direction.