hour and thereafter drawn over ceramic rods heated to a temperature of about 300 u00b0 c this heat treatment was repeatedly carried out alternately on the two sides of the folded length until the folded length was quite dry the heat treated material finally was vigorously washed out and dried in a drier after which the tacking threads were removed the silk material thus treated was found to possess pleated folds which remained quite unaffected after chemical cleaning and also practically unaffected even after washing at 60 u00b0 c and it did not change its appearance even when splashed with water a woollen material was treated in essentially the same manner as in example 1 except that after the first step and before the second step of the process the material was neutralized or oxidized with a bromate solution and then again washed out as before the woollen material was impregnated in the second step of the process with about 3 8 g calculated on the basis of the textile material after treatment had been completed per m 2 of a finely divided pbo frit powder and subsequently in the third stage it was heat treated at 280 u00b0 c in an oven the resultant pleated woollen material showed absolutely no change on chemical cleaning and showed practically no deterioration of the pleating after washing at 60 u00b0 c and subsequent drying in a drum drier an ultramarine blue woollen material was treated in a manner similar to that described in example 2 after the treatment with the keratolytic liquid and subsequent oxidation its colour value appeared a little brighter and after impregnation with the suspension of glazing or frit powder and the subsequent heat treatment this colour tone was maintained even after numerous washes a.