Photographic Chemistry Madness

Heyo! I'm a home photochemist ;*
I'm working on a lot of stuff, including my own silver photosensitive emulsion, but for now I'm willing to offer my help to anyone new to the field, especially with chemical bath recipes ~anything from partially or fully dissolving individual color layers in color film to dyeing photographic prints and lifting the emulsion from a broken glass plate~ and some general tips, especially since I specialize in old, expired film,,
Feel free to ask me anything!

[Edited on 2-20-2025 by Texium]

Quote: Originally posted by woelen

I also have done photography, combined with chemistry. On my website, there is some info on toning and developers. The toning part may be interesting for you. I also developed a yellow and green toner, based on vanadium, using the easy to obtain potteries V2O5. https://woelen.homescience.net/science/photo/toners/index.ht...

Quote: Originally posted by j_sum1

Nice topic. Somehow overlooked in this era of digital photography. People forget just how clever photographic chemistry is. There was an Aussie member (no longer active) who posted some interesting stuff on cyanotypes a while back and had some really interesting examples of his work -- using gallic acid in the process. He was kind enough to send me some of his chems. I still have some half finished projects as a result. I should get back to it. (But it won't happen this weekend.)

Phenosafranine synthesis and desensitization of panchromatic film

Heya! Below this message I attached an image of a ~probably correct~ synthesis of probably the simplest to make photographic desensitizer. As you can see, most of the path is just making 4-phenylenediamine which is a developer, so if you have it on hand feel free to go ahead with it. Desensitification can be achieved with concentrations as low as 0.005%, so you don't need much, and it can be used as a prewash or in the developer itself. As for the effects, it allows you to work on panchromatic emulsions on film and glass under normal darkroom light, so it can come pretty handy when you were shooting by feel ;)

Quote: Originally posted by chempyre235

Looks like a straightforward synthesis. For academic purposes, do you know how the o- and p- nitroacetanilides are separated, @NotANumber? It seems like this could present some problems, though I don't have experience with this. I thought of a possible route to p-phenylenediamine with terephthalic acid (from PET plastic) as the starting material: Neutralization to the ammonium salt; thermolysis to the amide; Hoffmann rearrangement to the diamine. (Can NaOCl be used?) I'd certainly like to know some thoughts of more experienced chemists on the viability and issues with this route.

They're separated pretty easily as o-nitroacetanilide is insoluble in alcohol :]
I took some time to write down the entire procedure, the second paragraph is theoretical for now, the first one is from two procedures given by Vogel

Quote: Originally posted by NotANumber

Heya! Below this message I attached an image of a ~probably correct~ synthesis of probably the simplest to make photographic desensitizer. As you can see, most of the path is just making 4-phenylenediamine which is a developer, so if you have it on hand feel free to go ahead with it. Desensitification can be achieved with concentrations as low as 0.005%, so you don't need much, and it can be used as a prewash or in the developer itself. As for the effects, it allows you to work on panchromatic emulsions on film and glass under normal darkroom light, so it can come pretty handy when you were shooting by feel

Quote: Originally posted by Texium

It's unclear to me how you are planning to get from the 4-nitroacetanilide to p-phenylenediamine. In your drawn out plan, you show 4-nitroacetanilide being reduced with iron to 4-amino-N-ethylaniline, then reacting that with water to yield p-phenylenediamine. Neither of those reactions should happen. Iron reduction of 4-nitroacetanilide should yield 4-aminoacetanilide. The amide will not be reduced. And the reduction may take more than an hour, as those heterogeneous metal reactions can vary in rate depending on the quality and surface area of your metal. It would be best to follow by TLC to determine when the reaction is complete, rather than assuming it's done after an hour. From there, you should be able to hydrolyze the amide by refluxing in aqueous HCl.

I read this in pop-sci and I haven't found any more information about this developer, does anyone know anything?

Quote: Originally posted by pneumatician

I read this in pop-sci and I haven't found any more information about this developer, does anyone know anything?

In general, this kind of development in rarely used, but pretty easy to conduct. The way it usually works is that the amount of developer soaked into the emulsion is ~about~ enough to fully develop around 1/3rd of the silver, making it very hard to overdevelop due to the fact that pretty much all of it is used up in the process. The downside is that if the entire roll contains a lot of bright areas, it'll come out slightly underdeveloped, but usually in normal photography it evens out.

As for the process described it differs in a way that instead of using an activating solution it uses air. If I had to hazard a guess, the developing agent could something easily oxidized, like unstabilized N,methyl-4-aminophenol sulphate or 2,4-diaminophenol sulphate coupled with urea to increase the in-emulsion perfusion. Alternatively, it could be low alkaline hydroquinone set up to overdevelop. As the reduction of silver halides to silver metal oxidizes the DA alongside oxygen from air, it decreases the developer activity, meaning that the less exposed negative the longer it's developed for before the DA gets fully oxidized. Pure HQ is an extremely high contrast developer, but as it's used up, the low-light areas get darker and darker lessening the effect. All of that is of course pure conjecture

But like I said, in my opinion it's probably a mix of hydroquinone, sodium tetraborate decahydrate, urea and sodium bromide to limit the fog alongside a tiny amount of sodium sulfite to limit the oxidation of the stock solution in storage