Comprehensive Anti-Fog Comparison

[bendytwin]

For the benefit of all, I want to conduct a side-by-side controlled comparison of anti-fog agents on extravagantly expired black-and-white film.

My motivation and context: I love hand-developing very expired black-and-white stock with my students. It provides an opportunity to engage with multiple aspects of hand processing, and is recuperative of materials that would otherwise go unused. I'm quite familiar with using KBr and benzotriazole on both expired paper and film. When manageable, I am using 50yr+ expired 16mm as camera stock, often rated down to single-digit ISO, pull-processed with anti-fog. But for stock that is too fogged for this purpose, I'm using it as PRINT stock in a contact printer, with a program to expose per-frame as long as needed to counteract the anti-fog speed loss. This opens up a lot of possibilities.

Here is a list of anti-fog agents I want to compare side-by-side and together in different combinations, keeping developer and film the same:

1. Potassium bromide
2. Benzotriazole
3. Kodak Anti-Foggant AF-2000 (used in ECN-2 at 5mL/L)
4. Kodak Anti-Fog #2 6-Nitrobenzimidazole Nitrate CAS 27896-84-0
5. Kodak Anti-Fog #5 5-Methylbenzotriazole CAS 136-85-6
6. Kodak Anti-Fog #6 3-Methylbenzothiazolium p-Toluenesulfonate CAS 6112-39-6
7. Kodak Anti-Fog #9 3,5-Dinitrobenzoic Acid CAS 99-34-3
8. "Phenyl Mercapto Tetrazole" or PMT, purchasable as Bellini Anti-Fog (1-Phenyl-5-mercaptotetrazole)

Of that list, I've got plenty of KBr, BTAZ, and AF-2000, and I can get the PMT from Freestyle as Bellini Anti-Fog. But I am lacking the rest and have never seen them readily available. Would anyone have a small amount of Kodak Anti-Fog #s 2/5/6/9 they can send me to experiment? Please feel free to message me or reply to this thread. If this list is incomplete from obtainable anti-fog agents I'd also like to know.

Several questions, some expansive and some specific, as I plan out the comparison
1) Anyone have experience using AF-2000 with black-and-white developers? What's its effectiveness?
2) Are the above anti-fog agents are "synergistic" with each other? (from experience it feels like KBr and BTAZ together are more effective than just higher doses of either alone)
3) How do different anti-fog agents interact differently with different developing agents? For my purposes, I am most interested in using it with D19 (metol/hydroquinone) for reversal, and in Xtol for processing as black-and-white negative.

Picture of a big stack of recently acquired 2498 Kodak RAR stock expired June 1981, and some 2475 Kodak Recording Film expired December 1979... from the near-opaque fog level it's apparently been baking in some forlorn military warehouse for most of the time since then.

 

[bendytwin]

Well, while I still don't have much of the above list, I was able to acquire some of the PMT as Bellini Anti-Fog. Not-entirely-objectively from my first tests, I think it works really well and synergistically with benzotriazole. Attempting to dial in an anti-fog / exposure / development regimen for the stock below got a lot easier with the Bellini addition. This is my first time using PMT.

Here's a successful development from today. Kodachrome II in 16mm, expired Feb 1973, rated at ISO .2
(yes, that's 2 1/3 stops below ISO 1)

Developed 4min @ 74.5F reversal as follows, in a heavy anti-fog developer:
2L D19 pH 10.4 + the following:

5g/L ammonium thiocyanate
90mL/L Potassium bromide 10%
180mL/L Benzotriazole 1%
20mL/L Bellini anti-fog
.5 gram/L extra hydroquinone (an old thread by David Lyga was helpful on this addition counteracting the contrast loss)
5mL/L potassium iodide .1%

Remjet was removed before development. Bleach was potassium dichromate, 2nd dev was plain D19.

Without the above anti-fog addition, a clip test of this film would go opaque black in about 30 seconds in total darkness.

I'd like to continue my comparison with more controlled examples. If anyone has any Kodak Anti-Fog #2, #5, #6, or #9, please message me.

 

[loccdor]

While I have nothing technical to contribute, allow me to say that I find what you are doing quite awesome!

 

[Disconnekt]

Not Kodak, but Flick Film released a "Fog off" that on the MSDS says the chemical name is "Benzotriazole / 1,2,3-Benzotriazole / 1,2-Aminozophenylene / 1H-Benzotrazole", the only place I know of in the US that has it on their site is Freestyle (here https://www.freestylephoto.com/301950-Flic-Film-Fog-Off-500ml)

 

[lamerko]

180mL/L Benzotriazole 1%?!! I really wonder how anything came out at all...
How did you shoot it at ISO .2?

 

[bendytwin]

Thanks loccdor, that means a lot to me. Sometimes when more failure than success happens, I just want to foreswear shooting expired stock ever again... but it always draws me back.
Thanks as well Disconnekt -- that looks like straight-up 1% benzotriazole. Glad to see it being sold ready-made so more paper & film can be resuscitated by people who don't want to mix from powder.

lamerko, it was a relatively sunny day yesterday, but even with a passing cloud, f/1.4 at 1/80th on a Bolex was plenty of light. On really sunny days, wide open, the EV is high enough you can even have a couple more stops to spare.

 

[bernard_L]

Very interesting to me! For two reasons:

• See : https://www.photrio.com/forum/threa...de-rc-deluxe-and-sparkling-highlights.213236/
• I was given some Kodak HIE, stored x?? years at room temperature. I tested with a few frames, at nominal, 2x, and 4x recommended (Kodak) exposure, and just got a hint of an image behind a strong fog. Seeing your promising results, I'll have another go with strong doses of anti-fog

I have KBr, Benzotriazole, and PMT in the form of Moersch Finisher Blue. Following your report, I'll add all three to the film developer for HIE.

Not-entirely-objectively from my first tests, I think it works really well and synergistically with benzotriazole.

I did note that you were prudent not making unfounded claims, but that looks encouraging; could you be a little more specific? I'll try to combine both. Looks like you can cut the fog but preserve the photon-generated image.
I'll stay tuned.

 

[Rudeofus]

This will certainly be an interesting test, but as you probably know: not all restrainers are born equal or differentiate themselves only by their pKa with silver. If you, for instance, look at Potassium Bromide, it initially restrains more and more, until it turns into a silver solvent. There is also a restrainer in your list PMT, which is by orders of magnitude stronger than bromides, so the comparison could become difficult. Ammonium Thiocyanate will be a restrainer at very low levels, only to turn into a powerful silver solvent at higher amounts.

If you can force yourself to stick to the main stated goal of your setup "which restrainer keeps fog of long expired film in check?", and pursue this goal with a single stock of film, then we may well learn something very valuable from this test.

Regarding getting this stuff: it would definitely be worth the effort to get in touch with the folks at Formulary and Artcraft, since they may have access to some chems even if they don't list them on their page.