New film developer idea (all powder!)

Ryuji said:

Maybe I'll give out a limited number of samples, but for that, I'll have to think about how to package and ship...

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albada said:

In my previous job, our products were subjected to "four corners testing": low/high temperature and low/high humidity. For a developer, the worst corner is probably hot-and-humid, and the south-east USA provides plenty of both.

So it would be interesting to test this in an area like Florida. A good test would be to have the tester keep the jar in the garage (no A/C), and open/close the jar once a week. If the powder keeps much of its activity after a year of that, it's solid!

Mark Overton

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Ryuji said:

I’m setting up a film processing station in my new commercial photo studio. I think I’m going back to all powder formulation, like I used to with DS-1 and DS-2. For small scale film processing, powder formulation offers more advantages than liquid concentrates, including long keeping properties. I’d rather weigh powder mix than viscous stock.

I’d probably formulate like this:

Part A:
ascorbic acid
Phenidone (or Dimezone S)
one or more water soluble polymers (cellulose derivatives, vinyl derivatives, and of course polyvinylpyrrolidone) and/or sugar alcohols (sorbitol, xylitol, etc).
any other additives

Part B:
sodium sulfite
borax
developer stabilizer additive

The only tricky part here is how to ensure uniform mix and prevent segregation in Part A. I think one or more water soluble polymers with suitable molecular weight and particle size can be used to “dilute” Phenidone first, wherein the Phenidone and polymer form cohesive aggregates. This is then mixed with the rest of ingredients in Part A. With this level of care in formulation, it is okay to just stir the jar before use.

Some of the water soluble polymers are actually known to improve image quality. Viscous developers are known to increase accutance and reduce granularity, although incompatible with spiral tank processing. I’m probably going to use polymers that are not viscous for this project, but something that has other effects, such as lower fog level and cleaner highlights. In the past, I experimented using several kinds of polymers in liquid concentrate stocks, but these polymers do not dissolve well in a concentrated sulfite solution. So, I often had to add them to the working solution. Powder formulation can just solve that problem altogether.

Another advantage of powder formulation is that we don’t need glycols and other solvents, and don’t need to handle viscous liquids. About the only and small negative is that I have to give up my favorite ethanolamine mix and go back to Borax.

If this approach works, I think it’s just a matter of stirring powder mix A in a jar, take 6 grams, take 50g of B, dissolve in a liter of cold tap water, adjust the temperature and it’s ready to go. (Numbers are just made up but they are realistic range.) This will be easier to dissolve than D-76 (stuff will dissolve while loading films into tank). I’d probably keep mix A in a vacuum jar to prevent moisture caking and oxidation.

Added bonus is that I can have a Part C, which can be used in place of Part B, to make a different developer. I’m most likely making Part B for fine grain (400+ speed films) and Part C for accutance (100 speed films), just like what I used to do with DS-1 and DS-2.

What do you guys think?

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Ryuji said:

The base unit is an induction based charger that sends the electric power to the handset without any exposed contact.

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