Ewesly / Holographic Formulae / Benign Ferric EDTA

Bleach solution

Original formula

 30 g  Ferric Sulfate

 30 g  di-Sodium EDTA

 30 g  Potassium Bromide

 10 ml Sulfuric Acid (Conc.)

 One litre water

Revised formula

 30 g  Ferric Sodium-EDTA

 30 g  Potassium Bromide

 30 g  Sodium Bisulfate

 One litre water

Processing

Bleaching time: One and a half times the time it takes to clear.

Temperature:  20C              Agitation:  Intermittent

Shelf life:  Possibly years, as long as the plate is well-washed of developer before bleaching to avoid contamination.

Less hazardous to work with than the dreaded PBQ.  Either version of the recipe gives the same result, the choice depending on the price and availability of the ingredients.  Leaving the solution exposed to air (uncovered tray) will extend the lifetime of the oxidizer.

Source:  Nicholas Phillips, "Benign Bleaching for Healthy Holography", holosphere, Volume 14, Number 4, p.21, (1986)