Sea water does make a good wash medium (it’s like a weak hypo clearing agent), and can even be a very very very slow fixer mostly for silver chloride emulsions so yeah sea water is pretty neat.
Quote:
Originally Posted by Tin Can
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Sea water does make a good wash medium (it’s like a weak hypo clearing agent), and can even be a very very very slow fixer mostly for silver chloride emulsions so yeah sea water is pretty neat.
Quote:
Originally Posted by Tin Can
Michael, I've been making inferences from Gordon Hutchings Book of Pyro...first edition - specifically, the section which begins on page 54 entitled "pH and Stain," which, while I won't retype the entire section here - starts with "Pyro stain is PH sensitive. Alkaline solutions increase stain and acid solutions tend to reduce stain."
Then again...I'd always used a used-developer after bath, which G. Hutchings, in his later edition(s?), stated was unnecessary as it only added to general overall stain (and thus density), while not specifically affecting various actual film densities.
Not sure if the above ties into anything going forward regarding density-specific staining, but as I've not tried PMK for a few years (have been using Pyrocat), I do plan to retry PMK without the after-bath.
At any rate...just a few thoughts - and I appreciate your feedback!
I got once taken to task on that point, John. And it seems all an alkaline afterbath does for PMK is increase an fbf effect of overall stain, and not differential stain, especially with semi-thick films like HP5 more than thinner emulsion films. I've worked with other pyrogallol and pyrocat tweaks, and developer alkalinity is important for the whole suite of ingredient activity. Here we enjoy high water quality piped in from mountain snowmelt reservoirs, so I only use distilled for the final brief rinse of film. But in much of the West, especially from private wells, the alkalinity of the water can be a significant factor itself. Michael should take a tour someday and sample the taste of real "hard water", with my first recommended stop being Stovepipe Wells in Death Valley. Kinda like a wine tasting tour for darkroom workers, but at times more like a soap tasting experience.
Yes the Book of Pyro... not a very good book about pyro. :) In any case, the point is TF-5 will work every bit as well as TF-4. That includes negatives processed in staining developers. There is nothing about TF-5 relative to TF-4 which will reduce imagewise stain density, and there is certainly nothing about TF-4 (or any fixer) which would increase imagewise stain formed in development.
Not sure what Drew is on about but I would say it is probably best to avoid using say Mono Lake as a water source for photographic or non photographic purposes.
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Originally Posted by John Layton
i've been using TF-5 for film and paper for a while now. It works very well, doesn't stink, and my FP4+ negatives developed in Pyrocat have a definite "imagewise" stain. I also use a citric acid stop bath, and my darkroom no longer smells like... a darkroom.
I'm quite satisfied with PF's product and have no plans to change back to anything else.
Sometimes improvements are indeed possible. Go for it John!
I'm a big fan of TF-5.
No word yet about TF-5 capacity compared to TF-4 or other rapid fixers.
Really, I'm at a loss understanding why capacities should be different for the TF family of fixers compared with, say, Ilford Rapid Fixer or Hypam. If there's really no difference, then one could use the Ilford tech sheets for these products as a guide for capacity and fixing times. The Ilford literature is detailed and includes capacity numbers for both "general purpose/commercial" and "optimum permanence" levels of fixation. I found the capacity numbers for the TF products to be rather sketchy and incomplete.
Michael R, any comments?
Best,
Doremus
TF info is straightforward, namely, with capacities intended for one-shot use, not re-use. Since they sell it as an "archival fixer", optimum permanence is the only game in town. It's not sold as a "general purpose" ordinary fixer meant to be used to the point of sheer exhaustion, or requiring a second bath. Bend the rules at your own risk. But they no doubt give somewhat conservative specs to provide a reasonable margin or error with reference to fixing time as well as dilution.
Hi Doremus, unfortunately the tech sheets for both TF-4 and TF-5 (like many PF products) are mostly marketing/hyperbole so there is not a great deal of information. The instructions for both indicate the following suggested capacities per liter of working solution:
15-20 rolls of film (or sheets of 8x10 or x4 sheets of 4x5)
30 sheets of 8x10 FB paper
60 sheets of 8x10 RC paper
That’s all we really have to go on. Fundamentally they are all principally ammonium thiosulfate likely in very similar working concentrations so when in doubt Ilford’s capacities can safely be relied upon to be conservative. Additional active/synergistic ingredients in the Formulary products which may or may not affect capacities are trade secrets so it is difficult to say much more about them. In the case of TF-5, since Ron (PE) had a hand in it, it is possible it is derived from one of his several rapid access superfix formulas (2-7, not disclosed) but we don’t know. I recall him discussing aspects of TF-5 on APUG so perhaps searching his posts on the subject would shed more light. Ron did not write the instructions on Formulary’s site.
People tend to make way too much of this, based mostly on bad and/or outdated/out of context information. If I were determined to not use Ilford Rapid Fixer and wanted something a little closer to neutral I’d either use Sprint (incidentally has higher indicated working solution capacities than the Formulary products), C-41/Flexicolor, or just mix my own (ammonium thiosulfate with some sulfite/bisulfite, which will have the same capacity as Ilford etc.).
Just one quick note of trivia for the pyro users - John Wimberley, the “father” of “modern” pyro formulas (PMK was based on WD2D) has always used plain old Ilford Rapid Fixer.
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Originally Posted by Doremus Scudder
I had a jug of that Ilford Rapid Fix on hand, and no, it did not work as well for my PMK pyro purposes as TF4. Gordon Hutchings got it right, and certainly was the father of the current popularity of pyrog. developers.