Bleaching is one of the key processes in the production of phase holograms with fine grain silver halide emulsions. This step was widely studied for discontinued Kodak, Agfa, and Ilford emulsions, and most of those results have been optimized with small changes for presently available holographic emulsions. A study of the different bleaching techniques with BB-640 holographic emulsions is presented. Some interesting new features found are the high-diffraction efficiencies achieved with direct rehalogenating bleaching and with reversal bleaching, with higher values and better sensitivities than those of classical fixation-free rehalogenating bleaching. In particular, we have found that the highest diffraction efficiency and the lowest scattering is obtained with AAC developer and reversal bleach R-9, with diffraction efficiency values of 82%.