Ewesly / Holographic Formulae / LN-7, Nick's No. 7

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Stock Solution

Lucky Number 7

30 g  Sodium Sulfite
10 g  Ascorbic Acid
 2 g  Chlorohydroquinone
 5 g  Potassium Bromide
10 g  Sodium Metaborate (Kodalk)
60 g  Sodium Carbonate (Anhydrous)
One litre water

Developing time

Three to four minutes for all materials.

Temperature:  22C +- 1C                        Agitation:  Constant

Shelf life

Probably about a month.

The first developer encountered which gave a better signal to noise ratio than CWC2, but with the same brightness.  It doesn't seem to work with Agfa film, but gives the best possible results on plates.  It was the main developer for true-color holography at Lake Forest College circa 1990.  A properly exposed plate will sit in this soup for thirty seconds before any density starts to appear.  It will last all day in a tray, about one week in a full stoppered bottle.


Nicholas J. Phillips, "The Silver Halides - the Workhorse of the Holography Business", Proceedings of the International Symposium on Display Holography, Volume III, 1988, p.35.

I dubbed this soup LN-7 as it was the seventh formula he had published in that paper, and it seemed to lower the noise compared to other developers thanks to the addition of the potassium bromide restrainer, hence Low Noise or Lucky Number 7.