POTA developer resulted in almost completely transparent negatives.

tomtomgps · Oct 2, 2024

Hi,

I tried POTA for the first time a few days back with Aviphot 80 (Rollei Retro 80s) exposed at iso 40. My negatives turned out almost transparent.
Has anyone encountered a similar issue ? I'm trying to understand what went wrong. I read that phenidone was prone to oxidation, if I accidentally
poured phenidone in the water before sodium sulfite could that be the reason ?

Any help would be appreciated
Thomas

lamerko · Oct 2, 2024

It is true that Phenidone oxidizes relatively quickly, but not that much. In fact, the recommendation for some sulfite in the beginning is for metol/elon.
Remember that phenidone is usually used in combination with another developing agent. Despite the large amount, you lose about 1 stop of film speed with this developer.
What could go wrong:
- your phenidone has been oxidized as a powder (it turns dark);
- you failed to dissolve it completely - phenidone is difficult to dissolve in water. That's why it's good to "help" him with a solvent - alcohol, glycol...
- you have a problem with sulfite - oxidized to sulfate or confused with sulfate;
- pH too low - sometimes tap water can play bad pH tricks.

tomtomgps · Oct 2, 2024

ok good thing I asked, I just realized I confused sulfite with sulfate
Thank you for your answer

qqphot · Oct 2, 2024

this is what has happened every time I've tried POTA as well.

Romanko · Oct 3, 2024

POTA must be used immediately after mixing, it loses its activity very quickly.
I had good results with Technical Pan developed in Barry Thornton's Two Bath developer. Technical Pan is also a high contrast film somewhat similar to Aviphot (but slower).
And yes, it has to be sulfite not sulfate. It works as accelerator and preservative.

koraks · Oct 3, 2024

tomtomgps said:
I just realized I confused sulfite with sulfate

That explains it; good catch @lamerko !

Don_ih · Oct 3, 2024

Also, it is very important to put the sulfite first. If you add phenidone to tap water, the water will immediately turn nearly brown as the oxygen dissolved in it ruins the phenidone.

tomtomgps · Oct 3, 2024

Ok so I bought sodium sulfite this time. I will develop a new roll this weekend and post the results.

Don_ih · Oct 3, 2024

Throw away the sodium sulfate.

Also, why do you want to use POTA for Aviphot 80? Regular developers (like D76 or Rodinal) can get perfectly good results.

POTA developer resulted in almost completely transparent negatives.

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