The standard recipe. You know. Not derivatives, modifications. Not D-76b/c/d/x/etc, just D-76. Which is listed on the first link I provided :P
Originally Posted by Ian Grant
Sodium Sulphite 100g/L
Sodium Tetraborate (Borax) 2g/L
Kodak D-76 is still 109g/L the same as the above recipe, so in order to include other ingredients, or increase one, something has to be reduced (ie: probably the Sulfite).
If it is otherwise D-76d.. 2g/L Metol, 5/gL HQ, and 8g/L Borax and 8g/L Boric Acid, logically Sodium Sulphite is 86g/L not 100g/L.
Of course the commercial stuff would also have a chelating agent.. in this case pentetic acid. The MSDS lists Boric Anhydride as the other chemical used, which is dehydrated Boric Acid.
So it should go B2O3 + 3H2O -> 2H3BO3
69.6182g + 3x~18.01528g -> 2x61.83g
Essentially, 1g of Boric Anhydride giving 1.78g of Boric Acid in solution.
Which goes on to form borates in water with the sulphite, altering the in solution formula.
Originally Posted by pierods
The standard formula that I used has 100g/L Sodium Sulphite. I am certain Kodak D-76 has less than that when mixed up in solution.
Logically I highly doubt that Kodak D-76 ends up with less than 75-80g/L of Sodium Sulphite in solution. So I disagree with the fact that amounts above 75-80g/L do not provide any more effect. I am experiencing a very noticeable effect. If theory doesn't match observation, there is something wrong with it.
Given that, and if people are reporting 75g/L D-76 recipe as sharper/grainier than Kodak D-76, logically it's somewhere between the 75g/L and 100g/L value.
Split the difference and it's 87g/L.
If there is 2g/L of Boric Anhydride in Kodak D-76 bag (it still has to add up to 109g/L), that puts Sodium Sulfite at 100g/L in the bag, but in solution, if my calculation is right, that would drop sodium sulfite to 89g/L, and 5.47g/L of Borax Decahydrate equivalency (I think, if my calculation is right).
Last edited by Athiril; 04-11-2013 at 08:50 PM. Click to view previous post history.