The Boric Anhydride Myth.
Since posting this recipe, I have done some research into the MSDS that I have for the commercially sold `Kodak` D-76 and I have also discussed the MSDS with a photo-chemist. The MSDS is as follows:
Weight % - Component - ( CAS Registry Number).
85-90 Sodium Sulphite (007757-83-7)
1-5 Hydroquinone (000123-31-9)
1-5 Sodium Tetraborate (001330-43-4)
1-5 Bis (4-hydroxy-N-methylanilinium) sulphate (000055-55-0)
< 1 Boric Anhydride (001303-86-2)
< 1 Pentasodium (carboxylatomethyl) iminobis (ethylenenitrilo) tetraacetate
Weight of concentrate = approximately 110 grams/litre.
From the book "Modern Photographic Processing" by Grant Haist, Volume 1:
Borate Alkali's: "Borax,Na2B4O7.10H2O, is the common name for sodium tetraborate, an alkaline compound used in the preparation of low-contrast, fine-grain developers. Borax may be written (NaBO2)2.B2O3, which shows the boric anhydride that limits the alkalinity possible from borax.
Borax acts as a buffer; that is, it maintains a reservoir of alkali but delivers only small quantities of hydroxyl ions at any one time. The alkalinity is maintained relatively unchanged until all of the borax has been neutralised."
It has been mentioned in some threads, that the Eastman Kodak D-76 packaged developer may be closer to D-76d, however, this doesn`t seem to be the case according to the description of borax in Haist`s book and it is probably very close, if not identical to the ORIGINAL formula as published over many, many decades. I wonder if anyone has conducted any test to compare the pH of the commercial EK product with the scratch mixed developer when stored over several weeks or months?
Last edited by Keith Tapscott.; 06-07-2008 at 03:55 PM. Click to view previous post history.