D-85 with formalin

[River Mantis]

This is the recipe of D-85 developer as found here. Part B is basically a common 37% formalin with addition of sulphite and bisulphite. So the question is, what's the role of these additions in part B and what if I just skip them and use pure formalin as part B and maybe adjust the sulphite content of part A to stoichiometrically match the amount of formaldehyde?

Solution A

• Water at 125° F — 500 ml
• Sodium sulphite — 36.5 g
• Boric acid crystals — 9.4 g
• Hydroquinone — 28 g
• Potassium bromide — 2 g
• Water to make 1 litre

Solution B

• Water at 90 ° F — 500 ml
• Sodium bisulphite* — 11 g
• Sodium sulphite — 1 g
• Paraformaldehyde — 37.5 g
• Water to make 1 litre

 

[Andrew O'Neill]

...or you could just use Acetone instead, as indicated in the formula. They raise the pH and act as the accelerator for the developer. Is that a Lith developer?

 

[koraks]

They raise the pH and act as the accelerator for the developer.

Yup, as also recently discussed here: https://www.photrio.com/forum/threads/msa-o-n-january-2024-decks.203932/page-2#post-2764171
@Don_ih has been experimenting with acetone/sulfite as the activator in developer, cf. Bishop's developer.

For lith developers specifically there's a thread here that's worthwhile having a look at: https://www.photrio.com/forum/threads/lith-developer-formulation-question.102948/

In my experiments with lith developers, I never found to be much magic in the actual developer, as long as it's (very) low in sulfite and only uses hydroquinone as the developing agent. I ended up mostly using a spin on Ryuji Suzuki's lith developer because it was super simple, cheap to make and very effective. Regardless of the developer used, what matters most is the combination of exposure and development, with massive exposure and very, very slight development giving the most dramatic (contrast, color/hue) results.

Paper of course plays a major part, too. Lots about this to be found online.

What did matter (a lot) was the amount and type of restrainer; large quantities of chloride gave pretty pink hues while bromide tends more towards yellow, at least on Fomatone paper. Another 'trick' that has a lot of impact is to use a 2-bath development approach with one bath being a developer consisting only of metol with very little or no activator and maybe only a bit of sulfite (I'd have to go back and check my notes). This will bring out a very light, low-contrast, colorful 'base' image on top of which you can develop a lith/infectious image.

Toning of course makes a dramatic difference; it's very powerful.

There's a couple more tricks along these routes; most of what I experimented with, I gleaned from Moersch' range of lith developers and adjuvants. By rooting in the documentation and SDS of those products, I was able to reconstruct a couple of interesting things.

My suggestion would be to look into these directions and not waste too much time on the formaldehyde/acetone thing. It's mostly just a very roundabout way to do something that's more easily done with more regular chemistry. I.e. hydroquinone, a tiny pinch of sulfite (<2g/l), some bromide or chloride (potassium or sodium; the ammonium salts tend to fog) and some (sodium or potassium) hydroxide or carbonate as an activator.

 

[Don_ih]

@Don_ih has been experimenting with acetone/sulfite as the activator in developer, cf. Bishop's developer.

I've been trying to get a continuous tone developer that can be "tuned" to whatever film I'm using to get the results I want. What I've managed thus far doesn't give results as good as Mytol.
I did mix up a lith developer using acetone (can't recall which one) and it didn't really work for me.