This paper reports experiments that confirm Belloni (2003) that pre-soaking a silver halide holographic emulsion in a dilute solution of the formate ion (HCO2-) will hypersensitize the emulsion by a factor of 5xs to 10xs, depending on the timing of development post-exposure. The quantum efficiency of the emulsion is effectively 1 in the first case. The extremely fine grain size of the holographic emulsion (Slavich PFG-01) is maintained and holographic image quality is excellent. When combined with a TEA pre-soak the expected TEA color shift is maintained.Appeared in Proceedings volume 10558 SPIE OPTO | 27 january - 1 february 2018. Practical holography xxxii: displays, materials, and applications.