POTA developer resulted in almost completely transparent negatives.

[tomtomgps]

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]

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]

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

 

[qqphot]

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

 

[Romanko]

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]

I just realized I confused sulfite with sulfate

That explains it; good catch @lamerko !

 

[Don_ih]

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]

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

 

[Don_ih]

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.