Wow; it's been awhile since I posted the formula. Here it is:
Originally Posted by Photo Engineer
Propylene glycol ................. 16 ml
Sodium metaborate 4 mol ..... 2.2 g
Ascorbic acid ..................... 4.5 g
Phenidone ......................... 0.05 g
I find it useful to multiply this formula by 3 and store in a little 64-ml bottle sold by the Formulary. I suggest *not* using a dropper-cap because they let more oxygen in.
Mix everything at about 75C, stirring continuously. Dissolve each ingredient before adding the next, except that Phenidone may be added when most but not all of the ascorbic acid has been dissolved. It only takes a few minutes to dissolve each ingredient. It can be hard to tell if dissolving is complete because there are many tiny bubbles that look like particles of powder. Stop stirring and if they tend to float upward, you're done.
To use, weigh into a beaker at the rates of 22.8 g/L of concentrate and 45 g/L of sodium sulfite, and then add water. Stirring for 3.5 min at 20C will dissolve all the sulfite.
Here are times in minutes at 20C:
These times might change a little as I do some re-testing.
"D316" is a temporary name. I'm thinking of calling it "KF-1" where "KF" means "keep frozen". It stores fine in the freezer, and I'll speculate that it'll last at least two years frozen.
I'm investigating reducing both the metaborate and ascorbic acid. This might allow us to use Dimezone S without crystallization.
EDIT: To put everything in one posting, I should have added the following about the results.
Compared with XTOL, this developer:
* Has the same grain or a hint finer.
* Sharpens a little less.
* Has the same density-curve, but with a slightly higher shoulder, and the toe might be slightly softer, but the difference is so small that it's hard to tell.
Last edited by albada; 01-10-2013 at 08:12 PM. Click to view previous post history.
Reason: Added image-quality results