We analyze the behavior of the diffraction efficiency as a function of the thickness of the relief holographic grating recorded on a phase emulsion composed by rosin and bromophenol blue (BPB) dye. The emulsions thicknesses are mainly due to the rosin quantity deposited on a substrate. We record holographic gratings on each emulsion using the spectral line k = 457 nm of an argon laser, after this we developed the emulsion with a quick process. The diffraction efficiencies for each grating vary from 0.25% to 0.62%.