I have the same formula in it's correct metric form from 1931.
Originally Posted by Photo Engineer
One problem with the US Military manuals was that they re-wrote formulae to what for them was more practical avoirdupois measures and quantities.
Nov., 1931 J PHOTOGRAPHIC SENSITOMETRY 701
p-Aminophenol hydrochloride 7.25 g.
Sodium sulphite (anhydrous) 50 g.
Sodium carbonate (anhydrous) 50 g.
Water to 1 litre
The developer was proposed by"Sheppard and Trivelli" as as a standard for Sensitometric testing.
It was adopted as as a standard "Scientific Sensiometric Developer for Arial Photography (8th International Luftbild Congress, Desden 1931)
So here again we have Sheppard working on p-Aminophenol developer at Kodak, 24 years after his work with Mees at Wratten & Wainwright.
This developer actually triggers a clue to Rodinal, all published formulae always use p-Aminophenol hydrochloride when carbonate is present in the developer, this forms the free base in the presence of carbonate and sulphite. While this is the method used to precipitate the free base there's considerable excess carbonate and sulphite which ensures the free base is dissolved in the solution.
So with no carbonate in Rodinal which we know uses the free base and hydroxide to form the phenolate there maybe a significant difference to a substitute formula using p-Aminophenol Hydrochloride.
We know that with PPD type developers the choice of the free base rather than a salt can be critical in some formulae, so it's likely this is why Agaf have never used p-Aminiphenol Hydrochloride in Rodinal.
Maybe p-Aminophenol Hydrochloride doesn't form the phenolate with Hydroxide.
Last edited by Ian Grant; 08-26-2009 at 02:13 AM. Click to view previous post history.