Thursday, September 15, 2011

Phenidone-C Divided Developer - Strangeness

I've been toying with the idea of a Phenidone-C divided developer akin to divided D-76 or Diafine.  Based on my experience with Phenidone-C so far, I propose the following formula:

Part A
Ascorbic Acid - 80g
Sodium Bicarbonate - 60g
Water - 750mL (make sure all is dissolved and effervescence stops)
Phenidone - 1g
Water to make 1L

Part B
Sodium Hydroxide - 1.45g
Borax - 6.92g
Water to make 1L

Agitate for 5 mins in part A then 5 mins in part B.

I did a quick test with the recipe scaled down to 100mL and use film clips to get an indication of activity.  What I expected to happen and what actually happened really surprised me.  I expected there to be no visible evidence of development in part A while the ascorbate + phenidone soaked into the emulsion and expected all the development to be visible when in part B.  To my surprise, after about 1 min in part A I noticed a slight darkening of the film and after two mins it was nearly black.  I thought I was going nuts here as everything I read and experienced showed that you need a higher pH to get decent activity out of Phenidone-C.  The time in part A is within range of a normal 8-10 min developer.  I thought I may have contaminated part A and increased the pH so I checked it with a calibrated meter and it showed 7.2 ... about what I expected being near neutral.  Now this is confusing ... ascorbate developing at a pH of 7.2?  I still don't believe it but I ran the same test 3 times with the same result.  I have no idea what's going on here and cannot explain it.  On the plus side I'm thinking with the really low pH this very concentrated phenidone-c-bicarbonate mix could be an extremely fine grained re-usable developer.

On one hand this really complicates my idea for a two part phenidone-c developer but on the other hand I may have stumbled across a new unexpected developer.

Next step is to actually process film instead of test clips to see real world results.  I propose two initial tests, one with just part A for 8 mins and one with part A for 2 mins and part B for 6 mins.


  1. both 100g of ascorbic acid and 1g of phenidone is a crap load. and you only need high pH for the ascorbate to be an active developer, otherwise it just regenerates phenidone continuously while phenidone develops.

    Reduce the pH to 6, less ascorbic acid, less bicarb

    1. Can you substantiate that in any way Dan?
      Links? pictures? discussion?

  2. I had tried last week.
    phenidone 0.25g+ Sodium ascorbate3g to make 500ml
    Sodium metaborate 7.5g to make 500ml

    Film: Eastman Doulbe-X 5222 @EI250

    A:2.5min agitation

    I think it worked, just for your reference.