Abstract: An improved mordant solution and process for preparing fibers for dyeing and fixing natural dyes to fibers, particularly but not exclusively cellulose fibers, including cotton and linen, and synthetic fibers, including Rayon.RTM. and Tensel.TM.. The improved natural mordant solution comprises an aqueous solution of alum KAl(SO.sub.4) and soda ash Na.sub.2 CO.sub.3, most preferably an aqueous colloidal suspension of aluminum hydroxide. This mordant solution significantly improves the recognized measurable qualities of naturally dyed fibers, including light and washfastness, without using polluting heavy metal mordants. The improved mordant treatment and natural dye process includes first pretreating the fabric with an aqueous mordant wash, which increases the dye uptake in the dye bath, then treating the fabric with a second aqueous mordant wash, following dyeing, then preferably treating the dyed fabric with a final tannin wash, permanently setting the natural dye in the fibers or fabric.

Abstract: An improved nonpolluting method of dyeing fibers or fabric, including natural cellulose fibers such as cotton or linen, using indigo dye. The improved process includes pretreating the fibers with a mordant solution, preferably a natural nonpolluting mordant solution. The fibers are then treated with a reduced indigo liquor in an inert atmosphere, preferably nitrogen. The indigo is then oxidized by flooding the dyed fabric with cold water. This indigo dye process can be adapted to conventional garment, package and piece dye processes and machinery, which has not been possible with existing indigo dye processes. The improved process results in a more consistent and even dyed material which is color and washfast.