Grant Haist was a researcher at Kodak and knew his stuff well.Ĭ-41 CD is well buffered - unless you have crazy water supply, pH should work with tap water as well as deionized water The C-42 formula has been published by Grant Haist, whom we can trust more than five people here including me singing high praises. I am very sorry for the prolongation, God bless you all. Kodak's crystallization fluid, where photoflo or MX12 is not available in the Egyptian market, is there an acceptable alternative?ġ0 - Finally - how many rolls of film that can be developed a quantity of one liter of that formula. What is the optimal formula for the Bleach / Fixer solution - or Bleach separately and the Separate Fixer, which is the optimal formula, whether they are combined with one or two solutions.ĩ - Also what is the optimal Stabilizer formula that does not depend on ![]() 6 The page here is two formulas, which is the final version of the experiment?ħ- What about the modified C27 formula - did it really prove useless?Ĩ. How much temperature should the installation process take?Ĥ- What is the temperature of the process?ĥ-Is that process really considered C42 - or to what extent are they really close? Have you proven successful and effective?Ģ - PH - = 10 - Question: Will the figure differ if I use deionized water?ģ. If you allow me, I have some inquiries about this. I am very embarrassed because of the many questions - I hope you do not get upset with me ![]() Any idea how long such an aqueous concentrate might last? In fact, I suspect the resulting stock solution would last a few weeks if the HAS and DTPA were present in the aqueous concentrate. One would mix both and use them one shot. I wonder if it would be feasible to split this developer into two long-lasting concentrates? One would be aqueous, and the other would contain CD-4 in an organic solvent such as propylene glycol. This tells me that the HAS can be omitted if the CD-4 is mixed and used within a few hours. ![]() The patent describes what happens if the HAS (an antioxidant) is omitted: After 24 hours at 57.5C, density drops 2.47%. There are small differences from RPC's formula, which he stated is a modification of the above formula. For the record, here's the one-litre formula from patent 5827635 referred to above. RPC: Thanks for posting the patent-number. In my experience the mask color seems to more closely match Kodak C-41 negs than the developer you mentioned and required less pH adjustment.Īnother poster on APUG, Stefan4u has posted a formula he concocted he calls C-27 which I have not tried but other APUG members have and claim it works very well. I have found an alternate formula from a patent: I never tried sulfuric acid to adjust the pH but it is better to use 28% or glacial acetic acid instead of white vinegar, that is what I use now, as it took me a lot of white vinegar to adjust it and that causes a slight dilution of the developer. The results I got were mine, yours and other's experiences may differ. Formulations aren't usually exact, pH-wise, as water pH may vary, even distilled, which I use, unless corrected for in the formula. I am no chemist, just a darkroom enthusiast but in response to your pH question, it is common practise to adjust the pH of color formulas to adjust for contrast and parallel curves. I never new the ultimate source of that formula, I think I found it on the Gerald Koch post you mentioned. ![]() Why did Kodak publish a formula that gives the wrong pH? Or did Haist publish it with an error? Or is antical #3 a strong acid so that omitting it (as RPC did) causes this large pH-shift? For that matter, does anyone have information on the C-42 process? My internet search turned up nothing. See this thread: (there was a url link here which no longer exists) Add potassium hydroxide (10%) or sulfuric acid (10%) to adjust pH.Įxcept for insignificant rounding differences, the formula above is identical to the "official" C-41 formula posted by Gerald Koch (there was a url link here which no longer exists).Īlthough the pH should be 10.00, RPC reports that the pH comes out to 10.4-10.5, and that he adds white vinegar to adjust pH.
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