I'm finally coming around on the benefits of 2-bath fixing, which I've resisted for a long time due to very limited darkroom counter space. I use TF-5. Trying to decide on an exact workflow, I'm leaning towards the following:
1. Start keeping separate bottles of fixer for film and paper. Film fixer gets a time-to-clear test when I'm developing a roll/sheet of film, and the final fix time will be 2x the clear time until it's annoyingly long or the fixer has passed its published capacity (TF-5). Alternatively.
2. For paper, keep two bottles of working strength TF-5 (standard 1+3 dilution in the published documentation).
3. After developer and water stop, fiber paper gets 1 minute in fixer bath #1, then goes into a large water holding bath until the end of the print session (generally no more than 2 hours; I can only print when my kids are asleep for the night)
4. At the end of the print session, all "keeper" prints get 1 additional minute in fixer bath #2, then a quick rinse, selenium toner, hypo clearing agent, and a final wash.
5. At some point, bath #1 is discarded, bath #2 becomes bath #1, and fresh fixer is mixed up to be the new bath #2. Presumably I'd want to have some kind of test for bath #1 to determine when it's ready to be disposed of. Is a film clearing test at the beginning of a print session workable for this test? What's the best way, in your opinion, to determine when bath #1 is done? Simply tracking the number of 8x10s I've put through it seems kind of problematic, because bath #2 will already have some, probably variable, number of sheets through it by the time it gets downgraded to bath #1. Open to suggestions here.
BHuji,
Your methods look good, just a couple of observations:
For fixing film, I usually just do a clearing test for a particular film and fixer combination (e.g., 320Tri-X in Ilford Rapid Fixer 1+4) and then fix all my film for 4x the clearing time. Yes, I know that 2x is enough, but that keeps me from having to do a clearing test before each batch. This builds in adequate fixing time for film when the fixer is close to exhaustion. Note that 2x the clearing time is the minimum time you need to fix; fixing film longer (and RC paper too) has no detrimental effects if it doesn't go longer than 4x the clearing time. I do test for clearing time as the film fixer reaches the end of its life and discard the fixer when the clearing time approaches 2x that in fresh fix. And, yes, do not use film fixer for fixing prints.
"5. At some point, bath #1 is discarded, bath #2 becomes bath #1, and fresh fixer is mixed up to be the new bath #2. Presumably I'd want to have some kind of test for bath #1 to determine when it's ready to be disposed of. Is a film clearing test at the beginning of a print session workable for this test? What's the best way, in your opinion, to determine when bath #1 is done?"
The best way I've found to deal with fixer capacity for bath one for prints is to track throughput. Ideally, you would do a residual silver test using the Kodak ST-1 test or the Kodak Rapid Selenium Test, determine the number of prints that you can safely fix before the test shows insoluble silver thiosulfate compounds in the print, then build in a generous safety factor (e.g., if you get 40 8x10s per liter before the test shows a positive, then settle on 35 or so) and use that number to keep track of throughput. If you do this test with just bath one, then, with two bath fixation, you're going to have no problems with adequate fixation. Then test the last print through your fixer occasionally just to make sure.
Alternatively, just use the manufacturer's recommended throughput. Be aware, however, that throughput capacity numbers for fiber-base prints for many fixers is based on a "general purpose" or "commercial" standard of permanence. If you're trying for optimum permanence, then the fixer capacity is much lower. Also, those capacity numbers usually apply to a one-bath fixing regime. FWIW, my throughput capacity for rapid fixers is 36 8x10s per liter for bath one. After that, bath two gets promoted to bath one and a new bath two is mixed. This cycle should only be repeated 5 times before both baths get mixed fresh. Bath two stays relatively fresh for up to 5 cycles (probably more, but that's a safe limit), so no worries about promoting bath two that number of times as long as it has only fixed prints that have been through bath one.
I tend to divide my workflow into printing and toning sessions. So, I print, develop, stop and give fix one, then wash my prints for 60 minutes. After I collect enough keepers, I'll do a toning session, which consists of a water soak, fix two, toner, water rinse, wash-aid and another 60 minute wash. This is nice with large prints since I only have to have four trays out at any given time (unless I'm doing overall bleaching, etc.). When doing this, however, I give the full fixing time for "commercial" permanence in a one-bath-fixing regime in my first fix. Then I can dry and store the prints for weeks, if needed, before doing a toning session.
Note the confusion about fixing time and capacities. Fixing time is dependent on fixer dilution (within limits, of course). Fixer capacity, on the other hand, is limited by the amount of fixer by-products that build up in the fixer with use. Therefore, capacity is not dependent on dilution, but rather the overall volume of the fixer, regardless of the dilution.
Stronger "film-strength" fixer, e.g., TF-5 at 1+3 or Ilford Rapid Fixer 1+4, will fully fix a print in a minute or thereabouts. The weaker "paper-strength" dilution (1+8 or 1+9 respectively) requires two to three minutes total. If you can keep the time short, you can shorten wash time, since the fixer won't have a chance to soak fully into the paper base (fiber-base paper, of course). The Ilford archival sequence is based on this and the fact that a longer treatment in wash-aid speeds washing. After a couple of minutes in the fix, however, the paper base is saturated with fixer and wash times have to be longer (hence my minimum 60-minute wash). The take-away here is that you'll likely have to wash rather longer with a two-bath fixing regime unless you can keep the fixing time short. I can't even drain a 16x20 print in less than 20 seconds or thereabouts, much less deal accurately with a 30-second fix in each bath, so I've just gone to using the weaker "paper strength" dilution and fixing and washing appropriately longer.
The KRST test for residual silver is easy and, if you selenium tone, the reagent is always at hand. I suggest you use it. The HT-2 test for adequate washing is its partner. Use that too.
Best,
Doremus