Home-brew C41 Chemistry - CD1
Recently, I came across a substantial amount of what I later discovered to be CD-1/T22/TSS. Most of the formulas that use it are for super fine grain developers, of the A49-type. A few Russian books referred to it as a color developing agent, giving formulas for the old ORWOCOLOR films. Now, as much as I enjoy the convenience of dropping off my color-neg films at the photolab and getting results the next day, I wanted to give home processing a try. :p
I have developed C41 films in RA-4 chemistry before, with enjoyable results (color were right, but the base had a green cast, presumably developer carry-over into the blix, I was happy, provided that I had no idea what I was doing :D )
I read the several threads on CD-1 as a color developer, and before going further, I am aware of the dye instability issues, the lack of saturation, and color balance offset. What follows is just my experience in formulating a C41 developer with the chemicals I have available (CD-1 goes at the price of p-aminophenol in Sigma Aldrich).
My first tests gave mixed results. My lacking knowledge in organic and photographic chemistry led me to believe that I had to include several developing agents besides CD-1. So I began with a 100g/l sulfite concentration ( 50x that of C-41 developer), 2g CD1, "some" Na carbonate, TEA, 1g pAP, 0.1g phenidone. The developer gave a pale color image, lacking in blue and green dyes, but color noetheless :) I switched various developing agents, producing the same results.
When I learned about the dye-formation inhibiting qualities of sulfite, I dropped the concentration to 2g/l. I also removed some of the chemicals that seemed to have little effect on development. What I was left with was sulfite, CD-1, KBr, and Na Carbonate, which gave full color rendition, albeit a bit pale and reminding of a hand-colored black-and white image.
Most, if not all, color developers include hydroxylamine in the form of the sulfite or HCl salt. Well, I don't have the compound, nor could I find it locally, so I was a preservative/stabilizer short in my formulas. The life of the developer was approx. 30min at 30C. Perusing patents by Kodak/Heist, I found that hydroquinone, gallic acid, pyrocatechol, and other hydroxybenzenes could be used to protect the hydroxylamine in the developer, so I reasoned that they could possibly act as a substitute. Unfortunately, even at 400mg/l, they acted as developing agents, and although they lengthened the life of the dev, it was an inappreciable change.
Patric Gainer's work on ascorbate as a preservative led me to my current formulation. I substituted ascorbic acid for the hydroxylamine at a concentration of 0.5g/l. This proved to be sufficient to extend the life of the developer to the point that after 12h in an open container at 30C, with occasional introduction of air and development of 2 rolls-equivalent of 135/36 color negative film left the developer in a light-rosy color, without turbulence or any precipitation.
Well, you'll excuse my verbosity :D, I hope I haven't been a bore; I just wanted to share the results of a CD-1 color negative developer, in which the developing agent is the only thing that's hard to find. If anyone is interested, I will post the formula and further details :)
Attached is an Epson V700 scan of a 35mm negative on Fuji Superia 200, shot at box speed, developed in my formulation, bleached in a ferricyanide-chloride bleach, fixed in a rapid (TF-3 like) fixer. Auto color adjustment in-scanner, slightly contrasty to show more color intensity, but the negative has detail preserved everywhere.
The shot is grainy and has color leeched on the left, owing to sloppy work :)
My brother as a prisoner of his sibling's experimental rages :D