STUDIES ON PERMANENT-SET OF WOOLEN FABRIC

The effect of pH of the water upon the crabbing of woolen fabric was investigated. Woolen fabrics were immersed in the water of pH of 7-10.5 for 1 hr at 50°C, which were pressed under the pressures of 0.5-4 kg/cm2 at 100°C for 5-20 min. immediately after being taken out of the water. The pressing was given to a sheet or a pile of 6 fabrics.The lustre, Lr of these fabrics decreases, in general, to Lr′ when they are released for 10 or 20 min. in the steam of 100°C. This decrease of lustre is less the more effectively the fabric is set at the crabbing. So L′r/Lr was measured as an appraisal of the effectiveness of the crabbing and the following results were obtained.(1) The crabbing is most effective when pH of the water is 9.2, when Lr and L′r/Lr are largest.(2) At pH higher than 8, H2S smelled during the pressing and the samples coloured yellowish slightly, It is interesting to note this correspondency of the evolution of H2S and the effect of the crabbing from the standpoint of the mechanism of the chemical setting.