Color processing bleach
PE has noted a couple of times that blixes are ineffective at removing the silver from color films, and that separate bleach and fix are really needed for color film processing. I used the Tetnal 3 solution E-6 process a few times a few years ago, and I could definitely see what he means. There was pronounced added density. (This is quite evident in the pre-exposed markings along the edges of the film, which are often invisible when processed in the Tetnal chemicals but are clear with the Kodak 6 solution kit.)
These days the only kits readily available for either E-6 or C-41 use blix. Has the blix been changed and improved enough to correct the previous problem? If not, can a simple bleach be used ahead of the blix to correct the problem?
Not AFAIK! Still the same old blixes and the same old problems.
consider a mix from scratch rehalogenating bleach so that all residual silver is removed in the subsequent fix step.
C-22 while not as environmentally friendly, in small quanities works well.
80g of pottasium ferricyanide and 20g of potassium bromide per litre.
2.5' at 38C 30' agitiation used to do fine for me.
I replenished 45mL per 80 sq in, and when 1l of replenisher used, would HHW dispose of the resulting 2L of worked and overflow. I may have been able to stretch it longer, but why risk it.
Once my find of 10L of e-6 bleach concentrate, found for free at the reuse shelf on one trip to the HHW drop off depot, runs out, I will be back to c-22 bleach for my c-41 and e-6 work.
my real name, imagine that.
A few companies have made excellent Blixes, Photocolor in particular. Used correctly Tetenal products are also excellent and they have a very long history which predated Kodak by decades and they always made/make excellent products.
There's good blixes and very iffy (not so good) and you need to be aware, blixes neeed regeneration in a part filled bottle plenty of agitation get more oxygen in . . . . . .
Lets look at it this way.....
Bleach III for C41 is used as is. No dilution. That is extreme but is usable for an illustration.
Now, Imagine a fix that is the same, requiring no dilution for use.
If you mix them together, you are diluting them 1:1 with each other and you slow things down.
This is an extreme example of the case. What really emphasizes this is when you surround the silver metal with dye clouds and when the silver has all kinds of "grunge" on the surface that must be scrubbed off before it can be bleached.
Analysis shows that out of the 300 mg or so per square foot, less than 10 mg per square foot should remain in order to get good grain and color. The leftover silver metal adds to grain and also darkens color. The OP has pointed that out to us. Well, in E6 you can also see a slight distortion in whites due to silver and silver sulfide.
Mike is correct, in that ferricyanide does a good job removing silver metal. However, IDK if current dyes are tested for image stability with ferricyanide. It is a strong oxidant. Oxidants are bad for some dyes.
I am, however, speaking from the POV of one who ran image stability and bleaching/blixing tests for over 5 years, and who took the ICIS short course in image stability.
In the long run, if you are happy, why worry?
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They were not interchangable. C-22 developer operated at 75 degrees F and C-41 at 100. C-41 emulsions are hardened and can withstand the high temperature, C-22 films cannot. Development times radically differed. But I believe the bleach and fixer are interchangable except for possible dye stabilty issues PE mentioned.
The film: C41, 2 equivalent couplers, FeEDTA bleach, Non Formalin hardener, no benzyl alcohol, no ferricyanide, Ammonium Hypo near neutral bleach, and etc. The list goes on including DIR couplers and high iodide emulsions. In no way were C22 and C41 compatible except for minor items.
I always heard that C22 was rather liberal, whereas C41 takes a much more conservative approach to development
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
I tested Unicolor E6 six bath versus three bath when the three bath came out and actually preferred, very slightly, the results from the three bath. But that was so long ago I couldn't tell you any more about why, just that I settled on the three bath. I didn't have any visible problems with it, and went through a couple of one gallon kits back when I was doing E6.
Weren't there concerns about the permanence of film developed in the three bath stuff versus six? I can't say anything about that. I have some slides from those days which look ok (and none that seem badly faded as far as I recall, but I don't have all of them by any stretch) but I didn't mark them as to which process I used so now I've no idea which are which.
Matt, I am not sure what you mean. Can you elaborate?
Roger, the 3 bath kit has no stabilizer or final rinse so there may be problems. Both Kodak and Fuji use some form of final stabilization along with a type of photo flo.
And yes, C41 color neg was a re-invention of color film from the ground up. E6 did not change as much but it was still a rather large leap forward.