Measuring tiny quantities of Phenidone and Potassium Bromide

So I have gotten this Mytol recipe to work as a stock solution really well for both FP4+ and HP5+. XTOL stock development times gave a bit more density and contrast than I wanted for FP4+ shot at 125, and were dead on for HP5+ shot at 400, but the images came out great on both rolls.

I went ahead and made up several "capsules" of pre-measured ingredients. The recipe for 250ml of stock solution is as follows:

• 15g of Sodium Sulfite (anhydrous)
• 0.35g of Borax
• 1.4g of Washing Soda (sodium carbonate monohydrate)
• 2.875g of Ascorbic Acid (vitamin C)
• 1.5ml of Phenidone solution (2.5% Phenidone in 99% isopropyl alcohol)

I keep the first three ingredients in a small plastic container as they are all alkaline. The ascorbic acid is kept separate from the alkaline ingredients in a different plastic container. The Phenidone solution is kept in a tiny glass vial. All three are combined and completely dissolved into distilled water immediately before use developing a roll of film, and this 250ml of developer is used one-shot.

A few days after making up 6 such "capsules," I used one to develop a roll of HP5+ with excellent results.

Out of curiosity I wanted to run a few films through using a 1:1 dilution to see if I liked it any better. Expected slightly increased grain, sharpness, and film speed. The roll of HP5+ I just souped came out completely, 100% blank. Not a camera problem, I had no edge markings either. Zero density anywhere. Developer completely dead.

As a sanity check I grabbed another capsule and mixed it into 500ml of water, then tossed a film clipping into it in room light for 12 minutes (same dev time as the roll that just failed). If the clipping darkened at all, it was imperceptible to my eyes.

Any theories what could have killed my developer? My best guess at this point is the Phenidone oxidized. I made the 2.5% solution with a nearly empty bottle of 99% isopropyl alcohol I had on hand that's probably 2-3 years old. Perhaps it had a higher water content than 1% due to evaporation, and that gave my Phenidone a very short shelf life? Beyond that I can't fathom. Dry ingredients that are this new and have been stored dry in a non-reactive PLA plastic container shouldn't be having any problems.

I'll try mixing some fresh Phenidone in new propylene glycol instead of old IPA and see if that will blacken a film clipping. But if anyone sees errors in my measurements or process, or has other theories what might have happened here, I'm all ears.

Update: After a few tests, I have confirmed it was indeed my Phenidone solution going bad. Most likely the IPA I mixed it up in was just way less than 99% concentrated due to age, which I guess would mean it contained a lot more water by volume than I thought. I mixed up a new 2.5% solution of Phenidone in propylene glycol this time and tested it with my last capsule of dry ingredients, and a snip of film went black quickly in there under room light, even at 1:1 Mytol dilution.

Here's hoping these new capsules don't run into a similar problem. But next time I'm about to commit a roll to Mytol that has been waiting for final mix-up for more than a week or so, I'm going to do a clip test before souping the real deal

BHuij said:

Here's hoping these new capsules don't run into a similar problem. But next time I'm about to commit a roll to Mytol that has been waiting for final mix-up for more than a week or so, I'm going to do a clip test before souping the real deal

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Indeed. It's wise to do a leader-test even with developer you're sure of. I don't trust any developer, even fresh.

Mark

Rudeofus said:

PS: my stash of powdered Phenidone is many years old and just keeps going. Don't worry too much about its shelf life.

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Strange, how did you manage that?
Mine lost power after about 5 years, although I bought it at an reliable and reputable supplier...

Philippe-Georges said:

Strange, how did you manage that?
Mine lost power after about 5 years, although I bought it at an reliable and reputable supplier...

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I don't remember doing anything specific. How did you establish the "lost power" fact: by discoloration, by "didn't develop any longer", or through precise measurements?

Philippe-Georges said:

Strange, how did you manage that?
Mine lost power after about 5 years, although I bought it at an reliable and reputable supplier...

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I bought mine 9 years ago, from an eBay seller from Poland. It works perfectly fine, I mixed some ID62 a month ago. It looks yellow and it might have been slightly lighter in colour when I bought it. Any 1% solutions I've mixed in propylene glycol keep very well.

BHuij said:

My best guess at this point is the Phenidone oxidized.

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This should be fairly easy to verify, since the Phenidone solution should have been quite severely discolored if it's oxidized, at least AFAIK. My phenidone stock in glycol goes pale yellow after some time (a year or so) in a half-full bottle. By that time, it still performs like new. I imagine that a 'dead' stock would have to be dark brown or black.

Also good experiences here with keeping dry phenidone. It doesn't seem to go bad very easily at all.

Rudeofus said:

I don't remember doing anything specific. How did you establish the "lost power" fact: by discoloration, by "didn't develop any longer", or through precise measurements?

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Well, the negatives got thinner and thinner, regardless elongating the developing time...
The Phenidone-A was diluted in isopropanol alcohol to 1%.
The colour of the Phenidone powder, kept in the dark, was slightly yellow-brown.
Now, I bought fresh Phenidone-S, from Bellini, and mixed a 1% dilution in Glycerine EF3 97% I got from the pharmacist.

Philippe-Georges said:

The colour of the Phenidone powder, kept in the dark, was slightly yellow-brown.

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Mine is either white and slightly flaky (from one supplier) or a very fine, pale yellow powder (another supplier). Both have been unchanged for years now.

The oxidized Phenidone I had in alcohol was kinda blackish. More to the point, it didn’t develop anything anymore.

The new stuff in glycol is amber colored although it’s a slightly stronger 2.5% solution.

The dry stuff is very pale straw/tan colored and a very fine powder. But it’s only a couple of months old at this point.

BHuij said:

The oxidized Phenidone I had in alcohol was kinda blackish.

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That's what I would have expected, indeed. Sounds like the alcohol solution wasn't as water-free as it should have been.
I tried an ethanol solution of phenidone once too, but found it oxidized far quicker than a glycol version. I stuck with the latter ever since.

Yeah If I'm honest, the alcohol was the product of impatience and nothing else. The glycol I ordered was delayed in shipping and I had everything else I needed to make Mytol, so I just mixed up the Phenidone in what I had on hand. It worked for immediate use, it worked a few days later, and it probably died shortly thereafter. I'm all switched over to glycol now and have new capsules made up that should store much better haha.

The Isopropyl Alcohol I used was rather pure, ≥ 99,7%, FFC,FG, CAS 67-63-0 from MERCK, hardly any water in it.
But I do agree that Glycerine is a better option, I hope at least...

Posting more updates here in case someone wanting to tinker with Mytol stumbles upon this thread somewhere down the line.

I just souped a roll of HP5+ in Mytol 1:1 and got excellent results. As expected, it is slightly grainier than HP5+ in Stock dilution. I hoped it would be a bit sharper and maybe give a bit more film speed too. I think it did give me an extra third stop or maybe two (EI 500 or 640). I'll check densities on my calibration frames when I get a minute. But I think I prefer the overall look of Stock. My scanner at 4000 DPI isn't grabbing any more actual resolution/detail/sharpness from the 1:1 roll, and it is getting more grain. So I think I'll standardize on Stock and keep 1:1 in my back pocket if I ever need the absolute most film speed I can get. Although I suspect if I need more than 400 at any point, I should probably just buy a faster film. Or get some Diafine. At any rate, true box speed from HP5+ is a luxury I haven't ever had with rotary processing in HC-110

Still will do some tests with FP4+ in 1:1 and Delta 100 in both Stock and 1:1.

I suppose a few pictures are worth a few thousand words.

HP5+ @ EI 400 in Mytol Stock with 100% crop:


HP5+ @ EI 500 in Mytol 1:1 with 100% crop:

I am surprised, that HP5+ in a 4000dpi scan looks no grainier than that. Are you 100% sure, that your scanner software didn't perform some magic here? A 4000dpi scan like that would give you a decent 13x enlargement, probably more, and HP5+ is not known to do that well.

I don't usually scan my negatives, so I couldn't tell you much other than that I'm using a Nikon Coolscan 4000 with Vuescan, I've turned off all the automatic stuff like grain reduction or JPG processing or profiles, and... well, Mytol has been pretty impressive stuff so far. There's definitely more grain in the HP5+ scans than my FP4+ ones (unsurprisingly).

That said, when I do want to digitize something I shot on B&W film, I will usually make an 8x10 silver gelatin print, and scan that on my flatbed. Seems like much less room for error in the scan that way, and it's much easier to get it to look on the screen the way it looks on the paper. And when I do this, the grain is sharper than when I scan the negative. So the Coolscan optical system is imperfect, and probably masking some amount of grain, even at 4000 DPI.