Could I replace the sodium sulfite in POTA with ascorbic acid and sodium carbonate for higher accutance ?

[tomtomgps]

I know nothing in terms of developers. I read that sodium sulfite dissolves grain. Can I modify POTA for more accutance ? I do not care about being able to store the developer fr a long time.

 

[Andrew O'Neill]

I always thought that POTA gave pretty decent sharpness, since semi-stand is usually given. You could try a tiny addition of Sodium Hydroxide. I've done this with D-23.

 

[koraks]

Can I modify POTA for more accutance

Maybe, but adding ascorbate + carbonate will make it into an XTOL-like developer - so no longer the very mild activity of POTA. In fact, if you keep the large amount of phenidone, it'll become VERY active also due to the higher pH of the carbonate. Moreover, because you're removing the sulfite, the shelf life will effectively become zero: the ascorbate will oxidize virtually instantly. This will cause dichroic fog/discoloration on the film.

Why not do the obvious and pick a different developer to begin with? One that just better suits your needs?

 

[Alan Johnson]

See chapter 11 of The Film Developing Cookbook 2020 by Anchell and and Troop for a multi page survey of options for developing document films.

 

[relistan]

Like @koraks said, even a tiny amount of ascorbic acid will vastly transform the nature of the developer because ascorbic acid is superadditive with phenidone.

 

[lamerko]

Moreover, because you're removing the sulfite, the shelf life will effectively become zero: the ascorbate will oxidize virtually instantly. This will cause dichroic fog/discoloration on the film.

Is this true for all developing agents like phenidone? If so, then that's my major fail with H&W!

 

[koraks]

I couldn't say; I just noticed it with ascorbate in an alkaline solution. It goes off pretty much instantly without any sulfite present to save it.