Cloudy F-24

[chris_raney1]

<p>I've been mixing F-24, non-hardening fixer as a second bath in conjunction with pre-packaged F-5 for my fiber paper for some time now. I often test the effectiveness of the F-24 by using using it to fix a test strip for about 30 seconds, whereupon I pull it out, drain and rinse it and expose it to strong light. Days later there's no obvious degradation of the image, so I'm reasonably assured the archival nature of my full fixing sequence should be adequate (ask me in a century). </p>

<p>But I still don't know why this stuff goes cloudy on me. Kodak's F-5 is terribly milky when it's mixed, but then it settles down the next day to a delightfully clear mixture. But since I make only a few prints on weekends I often filter and pour my fixers back into their respective brown glass, gallon jugs for use next time. The F-5 remains clear, but the F-24 (made from scratch according to Hoyle: Anchell's recipe in the Darkroom Cookbook) turns into what appears to be weak dishwater even after only a handful of prints.</p>

<p>I searched the archives on this site and back in '05 there was this same complaint. The solution proffered to the questioner was to add a bit of acid to the mixture. But duh...this is a non-hardening fixer, after all. The sulfite and the bifulsite play the role of preservatives, so I believe. Is this cloudiness an indicator this solution is degrading, as would a straight sodium thiosulfate solution? This chemical is too much of a hassle to make to declare it a use-and-dump elixir.</p>

<p>Do any of you wisened alchemists out there with your collective wealth of chemical lore have a contemporary answer for me? </p>

[frank.schifano]

<p>Could be a couple of things. If you add acid to a plain hypo fixer, the thiosulfate will be destroyed by the acid and the solution will turn cloudy. Sodium sulfite will prevent that, but only up to a point. After a few prints, enough acid might be carried over to start breaking down the thiosufate despite the protective action of the sulfite. Another possibility is the carry over of hardener to a neutral or alkaline environment. In a neutral to alkaline environment, the hardener will precipitate out and cloud the solution. Could be one, the other, or both things happening at once If you don't want a hardening fixer, why not just use F-24 for both fixing baths. That will solve the problem.</p>

[chris_raney1]

<p>Hmmm. You've made a valid point, Frank. As it is I'm using so much Kodak Selenium toner to penetrate that initial hardening caused by the first, F-5 bath that the ammonia smell is nearly driving me out of the darkroom, even with the fans blowing and the door open. I neither squeegee nor otherwise touch the emulsion on my prints, so perhaps I can simply do away with the Kodak product and its hardeners in the first fixing bath. As adventurous as I've been with chemicals I'm still little more than an acolyte to Ansel Adam's scripture of procedure.</p>

<p>I think you've opened my eyes, here.</p>

[larrydressler]

<p>Why use hardener for prints? that is for soft film?</p>

[frank.schifano]

<p>Chris, you can easily see how the hardener precipitates out in an environment that is not quite acidic enough. Next time you run some prints, transfer them from the F-5 fixing bath (with hardener) to a tray of water. Drain the print well before the water bath. Let them sit there for a while and watch how the water become cloudy. It doesn't smell of sulfur, so it's not the thiosulfate breaking down. But the plain water bath is not acidic enough to maintain the hardener in solution, so it precipitates out.</p>

<p>In any case, I've never had the need to use a hardener for prints. I suppose if I were using some very aggressive toners that soften the emulsion, I might need it, but for selenium and two bath bleach/redevelop sepia toners it's unnecessary. I'll make another plug for my favorite fixer here too, Kodak's Flexicolor Fixer and Replensher. Yes, it's made for C-41 but that's ok. Fixer is fixer and this stuff does the job. If you can source it locally, it's cheaper than dirt. $10 US will buy enough concentrate to make 5 gallons of working strength fixer. I double the dilution for B&W materials and it works great. Lasts a long time too. It's only mildly acidic with a PH of about 6.5 and has no hardener. If you use an indicating stop bath, it will turn blue/violet because it's PH will not allow the carried over indicating dye to remain yellow. Not a problem. Even as the PH drops further due to carry over, it will start to turn yellow. Again, not a problem. There's plenty of sulfite in there to protect the thiosulfate.</p>

[chris_raney1]

<p>No, I don't use Indicator Stop, Frank. The only proprietary chems I use are F-5, because it's worth the 5 bucks a package not to go through the hassle of making a 5-ingredient fixer, Kodak Selium toner, Photo-Flo; but because the latter leaves surface scum my wetting agent for film is Edwal's LFN. I play the role of Henry Jekyll for all the rest of my chemicals. </p>

<p>I'll simply use two trays of F-24 this weekend when I print. And yes, I'll certainly have to dial down the amount of selenium I use in my toning bath since it will no longer have to penetrate a hardened emulsion.</p>

<p>I think you might have cured my problem. Funny that neither Adams nor Anchell mentioned this problem with a two-tray, non-hardening second bath. Thanks for letting me pick your brain, Frank.</p>

[larrydressler]

<p>Another problem solved with all the gray matter here.</p>