Chemical and Mechanical Wear of Cotton Fabric in Laundering*

Abstract

International organisations are studying the standardisation of unsoiled cotton test pieces and methods of using them for the determination of chemical damage and mechanical wear in laundering. Of particular importance is the relation between chemical attack, as measured by viscosity or fluidity changes, and the corresponding strength loss. Study of the literature reveals that the available experimental data are far from complete and that published curves differ. In order to clarify the position, loads of test pieces of two different plain–weave cotton fabrics were laundered up to 35 times, without and with hypochlorite bleach, under different conditions, and an attempt was made to find the breaking strength loss corresponding to a given fluidity increase under identical mechanical conditions.It is concluded that, up to a 20 % strength loss, the relation between strength loss and fluidity increase is a linear one, provided that the severity of the chemical attack remains constant; above this value a curve similar to that of Clibbens and Ridge is found. In practice, however, test pieces are examined after a constant number of launderings, usually 25; consequently, low fluidity values correspond to a slow chemical attack, and high values to a rapid chemical attack. Under these conditions a curve is found that is similar to the Delft curve now under consideration for international standardisation, up toa 20% strength loss; above this value it remains similar to the curve of Clibbens and R idge.