Yarns, threads, cords or fabrics composed of natural or partially cyanoethylated cotton are treated with one of the following: methylamine, ethylamine, dimethylamine, trimethylamine, triethylamine, triethanolamine, ethylene - diamine, diethylene-triamine, 3-isopropoxypropylamine, 3-methoxypropylamine, 3, 31-iminobispropylamine, 3 - dimethylaminopropylamine or 3-isopropylaminopropyland are washed whilst under tension. The amine may be in liquid phase at normal temperature and pressure or in aqueous solution, and the tension may be applied before or during treatment with the amine. The tension may be just below that which would injure the fibres. The washing is effected with water. The treatment improves the tensile strength of the materials. Specifications 732,779 [Group IV(a)], and 767,810 are referred to.
