Abstract
Chinese tusser, eri and mulberry silk which were bleached by three different methods were dyed with an acid dye (Orange G), and the amount of dye adsorbed and the colored area of the samples bleached and dyed after bleaching were measured.
The bleached samples showed a decrease in the intensity of coloring, and a large increase in brightness too. The brightness of bleached eri silks was higher than that of mulberry silks un-degummed and degummed by sodium carbonate. In the case of chinese tusser silk which displayed a high intensity of coloring, the rate of increase of brightness by bleaching was very large.
Of the three different bleaching methods, the effect of bleaching by hydrogen peroxide to which oxalic acid and sodium tripolyphosphate had been added was slightly inferior to that of the others.
The amount of dye adsorbed by chinese tusser and eri silk bleached by hydrogen peroxide to which oxalic acid and sodium tripolyphosphate had been added and by sodium hydrosulfate was much larger than that by samples degummed and bleached by hydrogen peroxide to which silicate and sodium tripolyphosphate had been added. It is considered that this effect was associated with the adsorption of H+ during the bleaching treatment.
The brightness of the samples dyed after bleaching was higher than that of dyed samples un-degummed and degummed, even in the case of deep application of the dye.
