Here's a developer I discovered that gives XTOL-quality with D-23 simplicity. Well, almost as simple as D-23. But before I spend any more time testing this, could somebody tell me if this developer is already known? My searches didn't find this formula. It's so simple that I'm thinking that somebody must have already discovered it. Anyway, if your motto is "simple is beautiful", you'll like PC-Sulfite. Here's the 1-liter formula:

Sodium sulfite ................ 90 g
Phenidone ..................... 0.15 g
Ascorbic acid ................. 2.8 g

Target pH = 8.2 (same as XTOL).
Add 15% to XTOL's time as a starting-point.
I've only tested this with Tmax-400 (TMY) using distilled water at 20C. I shot all identical frames on a roll, and developed test-strips at 20C using XTOL and PC-Sulfite. Carefully examining the neg's through 22x loupes, I could scarcely see any difference between them. Same grain and shadow-detail.

PC-Sulfite contains no chelation agents and is not buffered, so its shelf-life will probably be short, even if you use distilled water. So use it shortly after mixing.
I use a 1% solution of phenidone in propylene glycol (PG) because phenidone is slow to dissolve in water.
The chemistry of PC-Sulfite is sufficiently different from XTOL that times might vary significantly from the "add 15%" time-rule above. Test first.
I haven't tried diluting it, but the pH of a sample of diluted PC-Sulfite matches that of diluted XTOL, so I'd expect it'll deliver similar results.

An interesting fact: You can be sloppy about measuring the ascorbic acid. For example, boosting the ascorbic acid will help the phenidone, increasing activity, but will also drop the pH, reducing activity. These effects roughly cancel out. My first test had 3.5g ascorbic acid, and the correct time was about the same as this 2.8g version. I haven't tried reducing ascorbic below 2.8g, but I'd say that being .1 or .2g off in measurement will have negligible effect.

In the DS-10 thread here and here, Photo Engineer (PE) was encouraging me to remove borate from a formula I'm working on due to environmental restrictions, and after doing so, and removing the PG-carrier as well, this is all that was left. It's so simple that I didn't think it could work, but it works great.

Well, did I just re-invent the wheel here? OTOH, if this really is new, then I'll test it some more.

Mark Overton