Ascorbate adventures, good and bad
I thought I'd do some experiments win Ascorbic acid; I think I've found every link on the internet. Of course, many were Gainer's or he contributed to others. Since I'm not a big fan of time/temperature, my interests leaned towards divided development or reduced agitation stand development.
So, at the suggestion of Jay de Fuhr (??) I mixed up as follows:
5 g Metol
20 g AA
20 g sodium sulfite (my contribution)
I then added sodium bicarbonate until the fizzing stopped. pH, 8.4.
For my Bath B, I used trisodium phosphate, tech grade, 1/2 tsp in a liter, pH 10.5. I intentionally wanted to try TSP at a low unbuffered rate for two reasons: One is I wanted high density areas to run out of steam, so to speak, and two, TSP doesn't swell gelatin and encourages finer grain (per Haist.)
I developed a roll of TMY-2 at 3 minutes each bath at about 80 degrees. At a glance the frames looked nice, but not special. Well, once I put the loupe on them with a proper light source, I was astounded! Beautiful grain, lots of local contrast. They practically jumped out at me. Whoopee!
Well, I can't duplicate that! I then developed a roll of Arista Premium 100. The shots tended towards muddy like overdevelopment everywhere, lots of fog (more like mud) in the low exposure zones.
I ran test snippets, both of frames and just leader ends, watching the latter develop in the light. The latter always came to a good eyeball Dmax. So I'm thinking the developer had not lost its activity. I also tried a double dose of TSP for pH 11.5.
I gave up and remade the developer. Slight variations: 17.6 g of AA, 4 g of sodium hydroxide. pH, 8.4. With some new test frames, like, dude, all but no development took place! Was my camera off? I'll have to check that. Dear Santa: all I want is the first result I got, all of the time!
Now, let me tell you about my attempts at using ascorbic acid in reduced agitation/stand development. I won't go into a lot of detail (do I hear cheers?) but the bottom line is all I can get is mud. I developed a test frame using my metol/sodium sulfite dilute developer for 60 minutes, looks good. I add a small measured amount of ascorbic acid, I get mud. I took the above developer, diluted it, and got mud. Score, 0-2.
I will double check my two camera's metering, but there are obviously other issues here.
Is this weird or what? What say you?
The two films have different Iodide content I would guess, and the grain sizes are different and .....
Well, you get the picture!
Sounds a bit like overdevelopment in the latter case (Arista) for some reason.
Films are cranky, and there is a definiite science to developing a developer... pun intended.
BTW, it is Jay de Fehr.
Yeah, but........ I think you've seen I'm a fair amateur chemist in these matters. And I know that ascorbates are still somewhat of an inconsistent mystery in practical use. But that no one has picked up on similar issues?
Originally Posted by Photo Engineer
I use several developers that incorporate ascorbates (including Pyrocat M-C, Instant Mytol and PC Glycol). I have found them to be consistent performers.
Originally Posted by Paul Verizzo
1. How did you make your test exposures?
2. Did you include exposure(s) of a step wedge?
3. Did you evaluate your results with a densitometer and a microscope?
4. What film/developer/ test subject did you use as a control?
Nothing quite so scientific, sorry to report. My test exposures are usually just a motor drive blast of my backyard in full sun, which includes a bayou and a boatyard, with a 28mm lens to gather many zones. I know that's a bit of a crap shoot, but as long as each test in the developer is the same, it's a point of reference. I know where to look for low zone and high zone, uh, zones. And what I experienced as described is beyond the need for densitometers!
Originally Posted by T Hoskinson
No, No, and dilute D-76 when I get a new film.
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Addendum: I meant to mention that I then take a few inches of the film that I "blasted" out of doors and develop it. It's just to get a general direction of what the developer is doing.
The ascorbate fooled me for about a month when I thought I had made a two bath phenidone ascorbate developer and I ran this test on a formula similar to that in the original post:
Sodium Ascorbate 22.6g
Water to 1000ml
Sodium Carbonate anh 5g
Water to 1000ml, pH~11.5
Take 20 ml Part A and add to 500 ml Part B.
It developed APX-100 film substantially after 4 min.
What would happen if this Part A and Part B was used as a two bath developer is that development would occur due to 20ml Part A being carried over on the film, tank and reel making the part B an ordinary non-exhausting developer.It would not be a true two bath developer where development occurs in the developer absorbed in the film emulsion.20 ml is a typical amount of carry-over in my tank.
I wonder if this development in carry-over is occurring with the developer formula given in the original post.
Numerous years ago the idea of using D-23 as part A of a two bath developer with a borax solution as B became a sort of fad. I thought it was miraculous until I got the necessary tools to make H&D curves. I found there was not a nickel's worth of difference in curve shape between D-23 and the 2-bath version.
If you use p-aminophenol base or phenidone in place of the Metol, you can use propylene glycol as solvent for part A. You can experiment with various activators for part B, including triethanol amine (TEA), sodium metaborate (part B of PMK works well), carbonate, etc. There is less chance of change of part A with time if you use glycol or glycerol as the solvent. Whatever you get the first time is more likely to be repeatable. A modicum of KBr may help keep the fog away. I would say, however, that it's not a good idea to reuse the part B in any case.
I used to use d-23 with metaborate as a B bath. It supported the shadows on minus development and I have the curves to prove it. That was a while ago but if films now are so thin it nolonger works then two bath developers don't have a snowball's chance in you know where. A two bath requires alot more developement to take place in the B than d-23 did.
Was it better than just plain D-23? I did a direct comparison years ago. Haven't bothered with the two bath since.