Method for controlling coloring of fiber

摘要

The present invention provides a method for controlling easily to make deeper-coloring possible in a method for coloring tryptophan-containing fibers by use of tryptophan. The method of the present invention comprises; a first step: a process for treating a fiber which contains tryptophan constitutionally or in which tryptophan is introduced from outside with an acid and an aldehyde compound; and a second step : a process for treating the fiber treated in the first step with an oxidizer in the presence of an acid.