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.
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 )
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 , 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
Last edited by Nikola Dulgiarov; 05-19-2013 at 12:55 PM. Click to view previous post history.
One of the reasons why Kodak went to CD-4 was the higher risk of skin allergy with the developing agents CD-1, CD-2 and CD-3. Of these CD-1 is the worst in terms of allergic reaction and cross-sensitivity.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.
~Antoine de Saint-Exupery
That is true, the package I have comes with a dire warning of skin toxicity. Once again, I try to follow all safety procedures and ensure minimal exposure. After all, I also use cyanide for fixing my ambrotypes. Treat chemicals with respect and nothing bad will come forth.
The reason I did this with CD-1 is that it's still available, at a reasonable price. CD-2 is also available, at 3x the price.
CD-1 is superadditive with Ascorbic Acid. As result we have less color and more bw. I was try this combo and reject it.
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Might make an excellent fine grain B&W developer though, it's worth a try. This is an area that's been neglected although Johnsons (Meritol), Agfa Atomal and May & Baker Promicrol usesimilar approaches.
Originally Posted by Relayer
CD1 lacks a 3-Methyl group. This group twists the resulting dye bond out of alignment and serves two purposes.
1. The twist adjusts the hues of the dyes, and the couplers were chosen to optimize the dyes with the twist. Without the twist, the dye hues are just a bit off.
2. The Methy group, combined with the twist blocks attack by oxygen and thus adds dye stability to the final dye that forms.
3. CD-4 is far less likely to cause allergic reactions and is as active as CD1. CD3 and CD6 are also unlikely to cause skin problems, but CD3 is much less reactive. CD6 is about as reactive as CD4.
Relayer, what I have seen with ascorbic acid is that added at concentrations of 350-500mg/l, it serves primarily to prevent oxidation and doesn't affect silver reduction. Of course, hydroxylamine H2SO4 or HCl would be the preferred agent, but I don't have it. The formula seems to work and produces a color image, so I'm happy
Ian, I have seen fine-grain developer formulas with CD-1, also some formula substitutes for developers like Tetenal Emofin include it. It would be interesting to see how ascorbic acid works in synergy with CD-1, possibly giving a speed boost, I haven't tried it.
PE, I have read the other threads on CD-1, and I'm aware of the implications of using it as a developing agent; however, it is readily available in Bulgaria, whilst CD2-6 are hard to come by. In the end, C-41 and RA-4 chemistry is sold even in the local photo store.
Just giving you some chemistry there! I understand.
CD3 was known internally as D2W or D2 modified by Weissberger. Remember hearing about him here?
from theory: oxidized form of color dev. agent forms a dye. any antioxidants such as sulfite, HAS, AA recovery CD and decrease dye forming. ideal color developer must be without any sulfite/HAS )) but this is impossible because short live. so level of any antioxidant must be low as possible.
Originally Posted by Nikola Dulgiarov
other way - one shot dev. it can be easy formulated without HAS and with low amount of sulfite.
some my experiment with CD-1 super fine-grain dev here:
Originally Posted by Nikola Dulgiarov