Process for inhibiting crust formation in reduced dye baths

In an aqueous sodium hydrosulfite composition for reducing vat or sulfur dye in an aqueous dye bath solution, comprising greater than about 10 percent by weight sodium dithionite, at least 1 percent sodium sulfite by weight of sodium dithionite, and stabilized by alkali metal hydroxide, the improvement characterized by including in said composition an effective surface crust inhibiting amount of an anionic surfactant selected from the group consisting of alkyl sulfates, alkyl aryl phosphate esters, N-acyl-N-alkyl taurates, .alpha.-olefin sulfonates, alkyl aryl disulfonates, dodecylated oxydibenzene sulfonates, and mixtures thereof, said effective surface crust inhibiting amount being in the range from about 0.002 to about 4.0 percent by weight of said sodium hydrosulfite composition.