A dye discharge composition exhibiting extended shelf life and/or pot life and high suitability for inkjet printing on dyed substrates, is disclosed. The composition comprises a reducing agent such as, for example, a sulfur-based reducing agent, and a chelating agent, such as a sodium salt of a polyamino carboxylic acid chelating agent. Use of the dye discharge composition in combination with a translucent colored composition and an optional opaque underbase composition, for forming an image on a dyed substrate is also disclosed. Processes for inkjet printing of an image on a dyed surface using the dye discharge composition, kits for use in such processes or an ink formulation containing same are also disclosed.

A method for coloring of cellulose in a supercritical CO.sub.2 medium by an uncharged hydrophobic dye, including at least the steps including of: (i) provision of cellulose fibers, (ii) placing the cellulose fibers in the presence of: a) an effective quantity of at least one uncharged mono organo-urea primer of formula RNHCONH.sub.2, where R represents a linear or branched, saturated or unsaturated, hydrocarbon chain possessing at least 3 carbon atoms, or a saturated or unsaturated cyclic hydrocarbon radical, which is bonded directly or via a methylene or ethylene group to a nitrogen atom, and if appropriate substituted under conditions conducive to the forming of a covalent carbamatic bond between the cellulose and the molecules of the organo-urea; and b) at least one hydrophobic dye in a supercritical CO.sub.2 medium, under conditions conducive to the immobilization of the dye on the fibers.