Coloration of Cotton with Clay Used for Ryukyuhanezu and Oudo Plaster in Japan

Abstract

The coloration properties of two kinds of clay used for Ryukyuhanezu and Oudo plaster were examined by immersing cotton fabric in a bath containing a slurry of the clay. The clay was ground and sieved to class six, and the particle size distribution measured. The composition of the clay minerals was determined by an SQX analysis and compared with that of the residual clay in the bath after immersing the cotton fabric. It is suggested from the change in composition of the clay that the main SiO2 crystalline component did not adhere to the cotton fibers and that the Fe, Al, S and Ti elements were related to the color. Satisfactory coloration was obtained by repeating three processing cycles of immersing while agitating the fabric in a slurry of 10 g of clay⁄g of fabric at 80°C for 50 minutes, drying the fabric for 24 hours and finally rinsing six times. It was found that several drying processes were very important for coloring the cotton fabric with the clay. Good color fastness properties of the fabric to washing and light was achieved with respective levels of 5 and 6 according to the testing methods of JIS L 0844 and L 0842.