Exhaust dyeing process for sulphur dyes

A process for exhaust dyeing cellulosic fibrous material with a sulphur dye, which process comprises contacting the fibrous material with an aqueous dyebath that contains at least one sulphur dye (S) in at least partially soluble form (S.sub.A) and at least one non-sulphide reducing agent (R), in a closed vessel in which an atmosphere of reduced oxygen level is maintained during exhaustion of the dyebath, subsequently raising the oxygen level of the atmosphere in the vessel by introduction of a gaseous form of oxygen, and then oxidizing in the presence of the raised oxygen level with an oxidizing agent selected from the group consisting of ozone, hydrogen peroxide and oxidizing salts, said atmosphere of reduced oxygen level comprising an inert gas which is nitrogen, a noble gas or carbon dioxide or a mixture of two or more thereof.

A process according to 29 wherein the raising of the oxygen level of the atmosphere in the vessel is effected by introducing air.

A process for exhaust dyeing cellulosic fibrous material with a sulphur dye, which process comprises contacting the fibrous material with an aqueous dyebath that contains at least one sulphur dye (S) in at least partially soluble form (S.sub.A) and at least one non-sulphide reducing agent (R), in a closed vessel in which an atmosphere of reduced oxygen level is maintained during exhaustion of the dyebath, and then oxidizing, said reducing agent (R) being present in a lesser amount than would be required to maintain an equally stable reduction bath under otherwise identical conditions but in an atmosphere having an oxygen level of normal air, said atmosphere of reduced oxygen level comprising an inert gas which is nitrogen, a noble gas or carbon dioxide or a mixture of two or more thereof.