Okay, this is not like the time I switched the fixer and developer graduates after a morning of photography. I am testing D-23, my standard developer, against Gainer's simplest Vitamin C (sodium carbonate, ascorbic acid, phenidone in alcohol solution) at pushed speeds, i.e., HP5 at E.I. 800 and 1600, for special 35mm and emergency 120 use. Reason: Vit C was too active for regular development when I tried it a couple of years ago, and it occurred to now me to try it for pushing.

I established the times for D-23. Here's what's happened next:

I tested the Vit C first with 35mm and established a 1600 time. I then split two rolls of 120, using two backs, one at each EI, photographing my test subjects on each. Plan: half-roll each at 800 and 1600, 4 separate developments in the two developers for comparisons.

I started development with the 1600 and 800 in D-23; all fine. Then1600 in Vit C at the same time that worked for 35: disaster! -- gross underdevelopment, as in, only high values showing any appreciable density. Developed the 800 half-roll with a similar result.

The 80mm of phenidone solution, mixed a couple of years ago, was stored in 2 40-ml dark bottles, only one slightly used. I tossed that one, even though it had worked for the 35mm, and ran a quick 35mm test with a fresh developer using the other, air-free phenidone bottle. Perfect, so I attributed the 120 problem to the developer. (I found an old post on Photrio mentioning the solution "going" suddenly after long storage. It recommended polyethylene glycol instead, in case anyone's interested.) I mixed all fresh phenidone solution with a new bottle of the recommended 91% alcohol (not Bacardi rocket fuel...)

I exposed another full 120 test roll this morning at 1600 and developed it in a fresh batch of Vit C. I noted that the developer solution was a darkish blue-black when I poured it out of the tank after development. Disaster again: almost no density, except an area in a couple of shots that fell on about Zone X and developed only into about a III density.

I pulled out my 35 again and ran a quick 8-exposure test, developed in another fresh batch: Perfect.

I am about to go up and test a sheet of 4x5, just to prove to myself that I'm not crazy, but wanted to get this off first.

I don't know chemistry. What could it be going on here? I mix 1 quart each time, with care to measuring (which is very simple anyway), temperature control, more-than-adequate volume used for the 120.

could it be the backing coating somehow? Might a pre-soak make a difference? Any experience?