Well, I'll try to answer as much as I can.
1. Kodak and Fuji cross license meaning they make identical kits. This results in the ability to use either film in either process. The dyes formed are different though, but the balance remains the same. Kodak adjust color paper sensitivity to account for both types of dyes, but AFAIK (and reports here seem to bear this out) Fuji does not.
2. Some kits are better than others. A blix is an oxidiant and reductant mixture that begins to spoil the minute the parts are mixed. Therefore, a single part kit, mixed at the plant will begin spoiling. Of course there are ways around this, and I would have to see the MSDS to even attempt to say whether any company has come close. I know that we solved the problem, but never used it at EK.
3. Powder kits are weak due to the fact that Ammonium Ferric EDTA is not available as a solid, nor is there a good source of solid Ammonium Thiosulfate which does not turn into slush rapidly. Some companies sell it, but it is very expensive. So, powder kits are sodium based and thus much weaker and slower than the ammonium kits. HINT: this is why Kodak went to liquid kits for blix, bleach and (years ago) fix. Ammonium salts are better!
4. If you make a bleach and a fix, these solutions can be as much as 50% more concentrated than when you mix the two into a blix. This is why most film blixes fail. They are more dilute. Here is an example. Let us say we have 50% solutions of ammonium hypo and ammonium ferric EDTA and mix them. They are now 25%. If we used them individually as is, they would be 50%. Now, this is for illustration only, but should give you an idea of the problem. And, often, using with longer times just does not work! It has to do with solvation of silver particles encapsulated within a big glob of dye and coupler. I have watched motion picture photo micrography of this process. It can leave up to 10% or so of the silver behind degrading color and increasing grain.
5. Some of you pay a premium for using an RA - Room Temperature kit. Well, in fact, RA chemistry can be used with Endura at room temperature all by itself. Interestingly, back in the 90s, these kits used formulas published by Pat Dignan to achieve this. To do it, they used CD-4 in place of CD-3. This causes broader dyes which give muddier colors and also gives significantly worse dye stability with color paper dyes (not with authentic C-41 dyes though). This is just a fact of chemistry and nothing inherent in C41 vs RA or EP3 or whatever process. I talked to Pat about that, and he retracted his Rapid Access formulas that used CD-4. However, if you see a color paper kit using CD-4, it will yield very inferior results.
As an added item, the Photospeed MSDS does list HQMS-K salt. But, I caution you that other ingredients not listed may or may not be present and therefore may or may not be present but necessary for proper operation and that is the problem with an MSDS. Some of the proper ingredients are present in a high enough concentration to require listing and I don't see them. Are they somehow not on the list due to laws pertaining where the MSDS is filed? IDK. So, I can feel good and bad at the same time. Missing from the sheet for example is the citrazinic acid in the color developer, the phosphate buffer (required in many countries), and the auxiliary developer in the first developer.
Make of it what you wish. I don't care what chemistry or formulation you use. I'm merely putting up information gleaned from my experiences.
Last edited by Photo Engineer; 07-27-2009 at 02:39 PM. Click to view previous post history.
Keith, I think part of the problem was smaller US companies tried to emulate the simplicity of the Photocolor products, but they didn't have photo-chemists skilled enough to do it.
Tetenal did have the photo-chemists, so their products reflect this.
The smaller US companies did have some excellent chemists, hired away from Kodak. Some came from GAF. These companies advertized in the Rochester Newspapers at the time and set up a group to do R&D.
Originally Posted by Ian Grant
At the time though they got no takers from Kodak except for a few from the plant or Photo Tech who worked on B&W and had done no color work AFAIK.
When our patent for a film blix issued, several of us were contacted by these companies. We turned them down.
In the UK I think things differed due to particularly good degree courses specialising in Photo-chemistry, at the University of London. Many Kodak & Ilford researchers passed through, including Mees, but others equally as able went to smaller companies.
PE and Ian Thanks for the answers. There are some imponderables still which may have to remain there forever but I note that at EK the blix problem was solved but just never implemented. Could it be that it was also solved at Tetenal as Ian has said or solved to the extent that any differences might take many years to manifest themselves?
I don't know how long the present Tetenal formulation for C41 blix has been in use but knowing the potential issue involving blix you'd imagine that tetenal research chemists would either have tried accelerated tests to ascertain negative longevity and re-printability before launch or even set aside films which had been processed in both blix and separate bleach and fix since launch of its blix kits and would have periodically done test prints from both sets of negs to monitor differences, if any, over say 1 year, 5 years 10 years etc
If Tetenal blix remains as good as or almost so as separate bleach and fix then the question remains why bother with separate chemicals and might the answer lie in the economics of large scale processing whereby blix is cheaper and easier for small scale amateur use but more expensive and not as convenient for large scale use such as even Jobos running on a small commercial scale or modern mini-lab production.
In any commercial process as in money the saying the "good drives out the bad" usually applies and if blix was still demonstrably and appreciably inferior then you'd imagine that Tetenal woud have quietly dropped the blix kits and turned its attention to producing small bleach and fix kits for the small scale amateur. Could it be that in the final analysis that blix may be very marginally inferior but from a marketing point of view a blix kits for the smallscale user has certain advantages such as smaller boxes, less complexity and quicker so overall its more convenient.
Looking at the Tetenal blix kit, I'd say it wins on all three aspects just mentioned and cynically or otherwise, the Tetenal marketing people might have calculated that few colour negs are ever going to be dug out and reprinted in the number of years in the future that it would take for the differences to begin to show.
Just a little thinking aloud on my part
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The unfortunate thing in this whole discussion is the near impossibility of getting Kodak C-41 kits of reasonable size in a reasonable manner in the US. I wish they just sold a small kit for home users. I don't really want to $150 to get enough bleach to make 50 gallons. Even if I did, I don't know where to order it from that will actually ship it...
The 5 litre Fujihunt C-41 kit is excellent value at £32. The Tetenal kit is £40.
UK retailers split Kodak minilab kits and they are very cheap
Alas, I have not found a US retailer who will do this.
Firstoff, we have RIT here with an excellent photographic chemistry course. In fact, the Japanese sent their students here for years until comparable courses were set up at Chiba university. The courses here, according to an undersecretary of photoscience in Japan, were excellent, but the Japaneese surpassed that in the late 80s turning out the equivalent of 25 PhD photochemists per year. RIT never went above the MS program. Today, most of them are out on the street, having been laid off!
As for the blix stability question, this has come up several times on APUG. People complain about the single part blix being cloudy or having a heavy precipitate and a sulfur odor. It is not my province to convince you, read those posts for yourself. This problem is not unknown and therefore not solved. I would not suggest a single part blix even though we could make one. It would still be poised on the edge of decomposition in one way or another I think. I have made compromises. Super Universal Fix VIII will work with Ammonium Ferric EDTA to make a usable film blix. Even so, it does not go all the way in providing the ability to keep as a single part kit.
As for those who have seen good results with these kits or formulations, you usually only look at single results and not comparisons. It is here that I have done work that most have not. Making direct comparisons way back when I did that sort of stuff showed the differences to be real and visible even though the "other formulas" by themselves looked quite good.