A compound that reductively reacts with a colored substance rendering it colorless and/or soluble. Reducing bleaches are considered less destructive to fibers than oxidative bleaches. However, compounds bleached reductively can oxidize in air thus reverting to their prebleach color.
Examples of reducing bleaches include:
sodium borohydride, tetramethylammonium borohydride, tetraethylammonium borohydride, sodium dithionite (sodium hydrosulfite); sodium bisulfite, sodium thiosulfate (Blankit), sodium formaldehydesulfoxylate (Rongalite), titanium trichloride, titanium sulfate