PC-Sulfite: A simple developer giving XTOL-quality
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:
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.
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.
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.
Great! Any idea what the conversion to Dimezone-S would be since I have that on hand....
Mark, I would strongly recommend against this formula as a practical formula. Despite your observation, formula like this is very intolerant of small errors and performance will be very much variable in practical situations. You are getting into roads that careful chemists avoid.
Borates are very useful buffering agents. There are some known downsides, and I wouldn't use it unless there is a good reason to do so. But any chemical ingredient that has any useful property has good and bad aspects. If you remove the buffering capacity and alkaline agent (borates) from your formula, you must balance with something else. You have to weigh risks and benefits of using each and all ingredients that go into formula and make a rational judgment.
Yes, an error of just a few hundreths of a gram of the phenidone will cause a substantial change. But an error of a gram of sulfite will make no perceivable difference, and I've verified robustness in the ascorbic acid. Further testing is needed to gauge sensitivity to type of water (if distilled/DI isn't used), temperature, dilution, and film-type.
Originally Posted by Ryuji
And I forgot to mention this recommendation: Dissolve the sulfite first, so it'll scavenge the dissolved oxygen.
I suggest 0.2 g of dimezone-S, because that's what XTOL uses. Others have changed this to 0.15 g of phenidone in XTOL-like formulae, so 0.2 g dimezone-s should be very close.
Originally Posted by RidingWaves
This formula is not robust against the errors made in the quantity of ascorbic acid. If you don't accept my knowledge on this topic, you should at least run somewhat decent sensitometric test, and report pH of each solution with varying amounts of ascorbic acid used.
Originally Posted by albada
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Yes. Changing the ascorbic acid will change pH. Yet I just re-examined my negatives developed with 3.5g and 2.8g of AA. Their densities are practically identical. But 3.5 vs 2.8 would be a 25% measurement-error. With the virtually the same results. That's robustness.
Originally Posted by Ryuji
Here are the pH's I measured:
3.5 g of AA: pH 8.21Notice that XTOL is well above 8.20. I thought my meter was reading high, but I did a two-point calibration, and it passes the Borax-test. Methinks that Kodak boosted the pH a little after filing the patent.
2.8 g of AA: pH 8.33
Ryuji, when testing DS-10, you noticed that some 100-speed films develop poorly below pH 8.2. I suspect that Kodak observed the same thing late in the game, and boosted pH to give themselves more pH-headroom. Either that or my meter's defective.
Yes, I think Kodak boosted it when they shifted the packaging way back when it first came out, I never could get a decent neg from Tmax 100. Now its not the case....
Just wanted to ask about Phenidone, since more and more esoteric names for this has started to fly:
I have phenidone from Photograpic Formulary
Cat no 10-0870
CAS no 92-43-3
I have done some searching:
- Dimezone (4,4 Dimethyl 1 Phenyl 3 Pyrazolidone)
- Dimezone S (4 HydroxyMethyl 4 Methyl 1 Phenyl 3 Pyrazolidone)
- Phenidone A (1 Phenyl 3 Pyrazolidone)
- Phenidone B (4 Methyl 1 Phenyl Pyrazolidone)
Dimezone S is almost as active as the original
Phenidone but with lower level of fog.
?Name? Dimezone, Phenidone D
Phenidone-A : 162.19
Dimezone, or phenidone-D : 190.24
Dimezone-S : 206.24
To me it seems obvious it is very important to know what type of Phenidone one has, and adjust the recipes for this, if comparing notes shall serve any meaningful purpose at all.
I just checked the CAS-number on my packet of phenidone from PhotoFormulary. It's the same as yours, 92-43-3. So that's what was used in PC-Sulfite.
Originally Posted by analog what is that?
Thank you Mark.
I have also another type of Phenidone here, or rather Dimenzione, but don't have the CAS number handy, will get back with that.
Hopefully the others here will also submit their CAS numbers, so we are sure we don't talk past each other and comparing apples with oranges......
PS looking at my notes, could this be the CAS number for Dimezione, and if thats the case, WHAT type Dimenzione exactly :
Last edited by analog what is that?; 12-30-2011 at 09:40 AM. Click to view previous post history.
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