Ewesly / Holographic Formulae / PBQ
30 g Potassium Iodide
15 g Borax
2 g Potassium Dichromate
2 g p-Benzoquinone added just before use.
One litre water
Bleaching time: One and a half times the time it takes to clear.
Temperature: 20C Agitation: Intermittent
Shelf life: Probably not too long after the PBQ is added.
Source: <a href="NickAdvances.PDF" title="The Origins of the Dreaded PBQ" target="_new">N. J. Phillips, A. A. Ward, R. Cullen, D. Porter, "Advances in Holographic Bleaches," Photographic Science and Engineering 24, 120 (1980). </a>