It's been two weeks, and I've run experiments changing the amount of ascorbic acid in the formula.
Here's an interesting observation. Pat Gainer's article here (http://unblinkingeye.com/Articles/Sy...synergism.html) on synergism has a graph that shows density versus ascorbic acid. It levels off when the ascorbic/phenidone ratio is 80. However, his test-developer was PC-TEA which contains no sulfite. If the developer has sulfite, the graph changes a little, as should be expected. With my developer, I found that activity levels off at a ratio of about 90.
XTOL, after converting chemicals into other equivalents, has a ratio of about 100. So I tried 100 in my dev, producing this formula:
Sodium sulfite ................ 45 g
Sodium metaborate ....... 3.1 g
Ascorbic acid ................. 5 g
Phenidone ..................... 0.05 g (in a 2% solution of PG)
pH = 8.16. For TMY2: 12.25 minutes at 20C.
The resulting H&D curve is an excellent match with XTOL:
The grain looks identical to me in both loupes and neg-scans. The JPEG file-sizes are equal, which objectively says the grain should be the same. Here are samples:
XTOL: 11-29-b8-XTOL.jpg Test-dev: 11-8-b8.jpg
Notice the sharpening in both along the horizontal line near the bottom. Would you say they're sharpening the same amount? You can see the fringes (Mackie lines) from sharpening even in the thumbnails.
Anyway, I wanted to post this as a way of establishing another milestone that says "here is a developer that gives results practically identical to XTOL."
My next steps are (1) mix this as a concentrate in propylene glycol, and (2) add a chelating agent that can chelate iron. That chelating agent might be useful because I noticed that this developer is dilute enough that it does not form precipitate when stored in the refrigerator (unlike XTOL). That means you can store it in the fridge and it'll last three times as long. That got me thinking: You can make more than you need, and refrigerate the rest until it's all consumed.
Comments and ideas are encouraged as always.