I've been tweaking my phenidone/c developers recently and learned a few interesting things so I thought I would share. Here are some quick points:
- The amount of phenidone is directly proportional to developer activity. Using PCB (19g borax + 6g ascorbic acid + 0.15g phenidone + water to 1L) as an example, reducing the phenidone from 0.15g/L to 0.1g/L makes a huge difference in developer activity.
- The more phendone/c you have, the lower pH you need for active development. I discovered that with enough phenidone/c you can have very active development at a pH of 7.2. On the other extreme, you can use ridiculously small quantities of phenidone/c (e.g. PCM uses 0.8g/L ascorbic acid + 0.02g/L phenidone) but increase pH for similar activity. This means you can adjust the activity of phenidone/c developers either by varying the pH or the amount of ingredients.
- More vit-c doesn't make much difference in activity but does extend shelf life. For example, using ascorbic acid at 4g/L vs 8g/L shows no discernable difference in activity but makes a re-usable developer last longer.
- pH does not affect grain very much. Grain from developers at pH 8.4 and 9.6 look very similar. This is based on observations with a scanner and RC prints.
- Stand development doesn't work the way we think. Testing showed no significant difference between full stand development (60s initial continuous only) vs minimal agitation (60s initial continuous, 10s every 5 mins) except for time when using a very dilute developer (PCM). Agitation more frequent than 5 mins showed more highlight development and increased contrast.
- You really don't need much potassium bromide. Even without potassium bromide, fog is minimal (most won't notice it), but adding 0.04g/L clears it up with no effect on developer activity.
If you like to concoct developers as I do I hope you find this useful.