An electrochemical reactor suitable for reducing dye to leucodye, comprises at least four electrolytic cells, wherein the electrolytic cells are provided in the form of at least two stacks of at least two electrolytic cells each such that one stack at a time can be separated for cathode or anode regeneration during suspension preparation.

An electrolytic dye reduction method comprises preparing a catholyte by dispersing a dye in a leucodye comprising electrolyte. In a preferred method the leucodye like leucoindigo is the sole dispersing aid.

The invention relates to a synergistically active composition which comprises a mixture of a sulfinic acid or a salt thereof and ascorbic acid or a salt thereof and the use of the composition as reducing agent. The reducing power of the composition of the invention is significantly higher than the reducing power of the single components.

An electrolytic dye reduction method comprises preparing a catholyte by dispersing a dye in a leucodye comprising electrolyte. In a preferred method the leucodye like leucoindigo is the sole dispersing aid.

Provided is a reduction dyeing method for indigo color using Nesterenkonia sp. KDB2, KDB3 and/or KDB4. The reduction dyeing method is relatively simple, efficient and allows good reproducibility, by using Nesterenkonia sp. KDB2, KDB3 and/or KDB4 bacterial strains instead of a traditional fermentation process which entails poor reproducibility and is exacting and complicated.

A method for dyeing a modacrylic/cellulosic fabric includes the steps of providing a fabric comprising modacrylic fibers and cellulosic fibers. An aqueous vat dye composition comprising water and a vat dye is applied to the fabric to provide a vat dyed modacrylic/cellulosic fabric. The vat dyed modacrylic/cellulosic fabric is dried. The vat dyed modacrylic/cellulosic fabric is then contacted with a reducing agent. The vat dyed modacrylic/cellulosic fabric is then steamed to promote dye penetration into the fibers. The vat dyed modacrylic/cellulosic fabric is then washed in a first wash step with a wash composition comprising water to remove excess vat dye and reducing agent. The vat dyed modacrylic/cellulosic fabric is contacted with an oxidation oxidizing agent. The vat dyed modacrylic/cellulosic fabric is washed in a second wash step to remove excess oxidation agent.

The invention relates to a synergistically active composition which comprises a mixture of a sulfinic acid or a salt thereof and ascorbic acid or a salt thereof and the use of the composition as reducing agent. The reducing power of the composition of the invention is significantly higher than the reducing power of the single components.

Provided is a reduction dyeing method for indigo using Dietzia sp. KDB1. The reduction dyeing method is relatively simple, efficient and allows good reproducibility, by using a Dietzia sp. KDB1 bacterial strain instead of a traditional fermentation process which entails poor reproducibility and is exacting and complicated. The method has the advantage of being able to substantially contribute to the field of dyeing using indigo, as the method can be used not only with natural indigo but also with synthetic indigo and makes it possible to efficiently increase the dye uptake of fabrics, and makes it possible to simplify difficult reducing processes including existing fermentation conditions which are exacting and complicated.

A dyeing apparatus (10) is described which is provided with a single tank (12) comprising: side walls (14); a bottom wall (16), which has a convex outer surface; a first inner partition wall (18) and a second inner partition wall (20), which delimit a dyeing compartment (26) and define respectively a first interspace (28) and a second interspace (30); and at least one mobile and/or removable upper lid (32), which closes the dyeing compartment in a watertight sealed manner. A first hydraulic circuit (34, 36; 38, 40) is designed for circulation of a first process fluid (B), whereas a second fluid circuit (42) is designed for circulation of a second process fluid (N). The first hydraulic circuit comprises first means (34, 36) for entry/exit of the first process fluid, which are designed to feed the first process fluid up to a first predefined filling level (L1) both in the dyeing compartment and in the interspaces, and second means (38, 40) for entry/exit of the first process fluid, which are designed to feed the first process fluid up to a second predefined filling level (L2) both in the dyeing compartment and in the interspaces. The second distance (D2) is greater than the first distance (D1), so that the second predefined filling level (L2) is greater than the first predefined filling level (L1).