C41 Fixer

highscore

Hi everyone. ? ? ? I don’t want to use a bleach-fixer in the C41 process, but separate baths instead. ? As the fixer must not be acidic during colour development. ? In my search for suitable fixers, I have so far only come across the MOERSCH Alkaline Fixer ATS. ? As well as the ROLLEI RXN Fix Neutral Fixer, which I use as standard in black-and-white development anyway. ? Can I stick with my current fixer (RXN) or do I need to add a second fixer to my shelf? Or should I switch fixers altogether? I’d obviously prefer to have just one on the shelf. ? Are there any other suitable fixers that I haven’t found yet? ? ? ? Thanks ? High score ? ? ? ?

jonny

Hi, You need a fixer specifically formulated for C41! As far as I know, neutral B&W fixers aren’t suitable for C41, as they lack certain additives. Conversely, however, you can certainly use C41 fixer for B&W, so if you only want to stock up on one type of fixer. C41 fixer is usually quite cheap too; for example, Kodak Flexicolor RA 2x10 litres for around €35. I’d be happy to give you the supplier’s details via private message. For black-and-white film, perform dilution of the solution at a ratio of 1:3; for paper, perform dilution at a ratio of 1:9. C41 is used undiluted, of course. But if you’re using paper, don’t forget the stop bath! Best regards, Jo

Wolfgg

Hello, SW fixers are too acidic for C41. The pH must be above 6.5; you could try ‘raising’ the pH of an existing SW fixer using NaOH. Otherwise, it would make sense to prepare your own from raw chemicals (depending on the formula, this requires only 3–4 chemicals). Regards, Wolfgang €

GeorgK

I’ve never really had any problems with ‘standard’ neutral fixers like RXN, for example. Nor do I believe that a slightly acidic fixer (just below pH=7) does much harm – what impact would the stop bath have then? In any case, the films clear up quite quickly, if only because you’re working at an elevated temperature (it doesn’t have to be 37.8°C during fixing, but around 30°C makes a difference). The special ‘miracle fixers’ are probably due to the specific conditions in a large-scale C41 lab (speed, shelf life). ? It can’t be any worse than that ‘Blix’ rubbish (unreliable, poor shelf life, expensive, an ecological nightmare) anyway. ? G.

jonny

Here are the facts again for your reference: € € Color processing myths dispelled € By Rowland Mowrey [...] € 10. Colour fixers are different / the same as B&W fixers. Fact: [...] Colour fixers are usually pH 6–7 solutions of ammonium hypo with ammonium sulphite added for stability, and sometimes they contain accelerators to assist in silver removal. Remember, in colour, one roll of film is roughly equivalent to three rolls of B&W because of the three layers, plus you are removing every bit of silver (you hope). Also, that silver is held in place by heavy doses of DIR coupler residues and other image-enhancing chemicals. So... you take a guess. Which is more complex? Colour fixers are a bit more complex. A simple fixer will work, but you have to leave the film in the fixer for about twice as long to remove the silver halide. AND... all colour fixers are unhardened. So never use a hardened fixer or a strongly acidic or basic fixer on colour films unless you want to ruin your images or at least seriously distort them. € I hope that answers the questions raised here. I will continue to use C41 fixers for fixing colour films in future, especially as I see no economic advantage over black-and-white fixers. But of course, everyone is free to do as they please.

grommi

I’ve always used black-and-white fixers for colour films as well, and I’ve never had the slightest problem. The clearing times are sometimes considerably shorter than those for black-and-white films, as the silver content in colour films is very low. If you rinse thoroughly between steps after the Bleach bath, I believe you can fix both black-and-white and colour films in the same working solution – you just have to make sure you don’t carry any bleach over. The bleach bath is extremely acidic, so why shouldn’t you use an acidic fixer? I’ve had no problems with this either, even after processing hundreds of films. “But of course, everyone can do as they please.” € Speaking of rinsing between stages. The C-41 process was designed for machine development without a fresh water supply. In my opinion, this has given rise to many myths. If you rinse between stages at home after every bath, everything becomes much simpler and, in my opinion, better.

jonny

I’ve always used black-and-white fixers for colour films as well and have never had the slightest problem. The clearing times are sometimes considerably shorter than those for black-and-white films, as the silver content of colour films is very low. If you rinse thoroughly between stages after the Bleach bath, I believe you can fix black-and-white and colour films in the same working solution; you just have to make sure no bleach is carried over. The Bleach bath is extremely acidic, so why shouldn’t you use an acidic fixer? I’ve had no problems with this either, even after developing hundreds of films. “But of course, everyone can do as they please.” … Speaking of rinsing between baths. The C-41 process was designed for machine development without a fresh water supply. In my opinion, this has given rise to many myths. If you rinse between baths at home after each stage, everything becomes much simpler and, in my opinion, better.

Grommi, the quote above is from Ron Mowrey, a chemist and retired engineer who helped develop the C-41 process at Kodak back in the day. Not only does he possess insights into the chemistry of the process that you or I completely lack, but his name also appears on one or two relevant patents. You are perfectly entitled to argue here that your method works for you and your requirements – no objection. But please don’t try to tell us here that the man actually has no idea...

grommi

But please don’t try to tell us that the man actually has no idea... ?

Why so hostile? I didn’t say that at all, nor was that my intention. The standard C-41 process was developed for fast and reliable processing. Of course, in a minilab – the sort that used to be found in every large supermarket and was often operated by a semi-skilled assistant – all process specifications should be strictly adhered to. That naturally includes the fixer used. In a home lab, at room temperature and in the can, there is much greater flexibility and the results can even turn out better than in a commercial lab, which always has to operate with a focus on maximising output. Applying these rigid rules to the home lab contributes significantly, in my opinion, to the creation of ‘myths’. ? “You are perfectly entitled to argue here that it works for you and your requirements even using your method,” Meaning that, given my (modest?) requirements, I can actually use a black-and-white fixer that is unsuitable? ? C-41 development at home is really very simple. I mix my colour developing agent myself from raw chemicals; the working solution lasts significantly longer than with ready-made products. I develop at room temperature, fix with black-and-white fixer and do not use a stabilising bath but rinse thoroughly. The resulting negatives need not shy away from comparison with professionally developed negatives.

HGR

Grommi, I like that! Could you quickly list the raw chemicals needed? Or give me a reference? I’ve got water and black-and-white fixer, and I’d be happy to give it a go! € Best regards € Hans-Gerd

Wolfgg

Grommi: But you surely know that the consequences of deviating from Kodak’s specifications can only become apparent years later. For example, in the form of colorants that fade away ‘a bit sooner than promised’. Around 1975, I also experimented a bit with the chemistry. I can’t say for certain whether it’s related, but some Kodak films from that time are now in such a state that it’s not even worth scanning them. The magenta layer has completely disappeared. The man from Rochester is being cautious for good reason. I’ve also studied his posts on Apug many times. Incidentally, the bleach also has a pH of around 6.5, so it is by no means very acidic. The most acidic C41 bath for home users is likely to be the 1% acetic acid stop bath. My only ‘independence’ today is the formalin-containing final bath, which the faint-hearted have done away with. Even with E6, it’s good life insurance for the gelatin and everything in it. Hans-Gerd: http://www.fotolaborinfo.de/fotolabor/fcnans.htm Regards, Wolfgang €

grommi

Grommi, I like that! Could you quickly list the raw chemicals needed? Or give a reference? I’ve got water and black-and-white fixer, and I’d be happy to give it a go! € Best regards € Hans-Gerd

Sure, see here, including processing instructions and example images: € http://www.filmwasters.com/forum/index.php?topic=8224.0 € I got the recipe from APUG and it’s more or less approved by “photoengeneer”, also a former Kodak employee. I can’t find the original APUG thread at the moment. € By the way, the Bleach bath is available as a liquid concentrate (unfortunately not from the host) and lasts forever. You can regenerate the working solution by shaking it to introduce atmospheric oxygen, until there is too much dilution due to carry-over from the bath.

grommi

Incidentally, the bleaching solution also has a pH of around 6.5, so it is by no means very acidic. The most acidic C41 bath used by home users is likely to be the 1% acetic acid stop bath.

I’ve just measured the pH of my ready-made Bleach bath, prepared according to the instructions: pH 4.0 € Admittedly, that’s not as acidic as your acetic acid stop bath (pH approx. 3?), but my SW fixer, prepared according to the instructions, is not as acidic as the Bleach bath at pH 4.7. And I don’t use an acidic stop bath, but water. € So much from me on the subject of ‘myths’.

Wolfgg

Hello Grommi, A pH of 4 in the bleach-fixer does seem a bit odd to me, because if the pH in the bleach-fixer or fixer is below about 5.5, some of the cyan dye may be converted into what is known as leucocyan, i.e. a colourless cyan. This results in a lack of final density in the cyan channel. This applies to C41 and E6. But perhaps the inventor of the bleach has compensated for this effect in some other way. Here are two quick links: http://motion.kodak.com/uploadedfiles/motion/US_plugins_acrobat_en_motion_support_processing_h333.pdf http://photo.net/film-and-processing-forum/00dXUt Just a heads-up about the pitfalls that can arise with ‘DIY’ processes. Regards, Wolfgang

grommi

Here are two quick links: http://motion.kodak.com/uploadedfiles/motion/US_plugins_acrobat_en_motion_support_processing_h333.pdf http://photo.net/film-and-processing-forum/00dXUt

From the second link: “Again I point out that modern films are not as prone to a leuco-cyan dye condition. If your film should show signs – you can re-fix in a fixer with pH 6.5”. ? As mentioned above, I haven’t had any problems with colour shifts so far. I keep reading that people have problems with colour-accurate scanning of colour negative film. These problems are completely foreign to me, whether developed by an external lab or at home using ‘my’ method. However, I haven’t yet tried this with any film from 1972. That was the year the C-41 process was introduced. ? PS: perhaps the manufacturer of the Bleach bath had a reason for setting the pH to 4. It is, in fact, only slightly acidic and not extreme, as I mistakenly stated above. Since C-41 also has to run on machines without washing between baths, a slightly acidic Bleach bath would have advantages, provided it has no visible effect on the colorants. This is, of course, speculation. In my opinion, what matters is the ‘end result’. ? Bleach bath is still available as a 1-litre concentrate (remaining stock?), but I can’t find any colour fixer in 1-litre containers, only bleach-fix. However, neutral black-and-white fixers have been available for a long time, and they don’t cost any more than the acidic ones. Anyone who needs a new fixer and also wants to develop colour with separate baths – for which there are, of course, good reasons – can use this one.

highscore

Hi everyone, Thank you very much for the detailed discussion. Let me make an abstract of things for myself. Of course, a fixer manufactured for C41 is best. The pH value of a chosen fixer should be > 6.5. Facts According to the data sheet, the Mörsch ATS fixer has a pH of 7.8. In the solution, the pH is 7.5–8. The RXN has a pH of 6.6. According to our landlord, the pH value in the solution here is 6.9–7. Conclusion (for me) Both fixers can be used. Highscore