I have always used a 1-bath fixer system, but some people advise me to use a 2-bath fixer system. They say it lets the fixer last much longer and it is better for the prints in the long run.

Which is best, 1-bath or 2-bath system, and why?

I appreciate your experience.

Ned Finkel Lancaster, New Hampshire

-- Ned Finkel (nfinkel@mindspring.com), January 09, 2002

Answers

The best fixing system for manual processing of film and paper at regular 20-25C temperature on modern film and paper is one bath non-hardening rapid fixer. I recommend that you do not prolong fixation time for fiber based paper and limit to suggested processing capacity of the chemical.

With rapid fixer, when above conditions are followed, two-bath system gives negligible advantage in terms of washing effort or print permanence. If you want to squeeze maximum capacity out of the fixer solution, mix weaker concentration suggested by the manufacturer and follow their longer processing time. Fixer's processing capacity doesn't change much by dilution within a reasonable range.

Many recommendations, especially from those with long experience, tend to be based on outdated knowledge or practice. EKC's popular recommendation is to use two-bath but that is because they assume acid hardening non-rapid fixer is used (the worst fixer for normal hand processing in many respects). That maybe an idiot-proof dogma, since it doesn't do harm even with a modern rapid fixer, but it's unnecessary and cumbersome. My recommendation is pretty much the Ilford system, which is based on knowledge published on photochemical journal papers.

If you like to know more technical things, you might find my note somewhat useful:

note on fixer

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), January 09, 2002.

I guess I'm just an old fogey mired in the past, but I use non- hardening rapid fix in two baths for 30-45 seconds each. I figure, if one is good, two is better. When the second fix has been used for half the recommended number of prints it is capable of fixing, it moves to the first fix and I mix fresh for the second fix. I'm not so much concerned with extending the life of my fix as I am with assuring that I get adequate fixing. I worry that, with a single bath, when you are down to the last few prints the solution is capable of fixing, 60 seconds may not be adequate. I feel the two- bath system is insurance against underfixing, and I've been doing it for so long it doesn't seem like any extra trouble.

In regard to fixing, Ilford states "...print throughput can only be a guide as it depends on the proportion of black areas on the print." They recommend that you test individual papers for proper fixing if you are intent on obtaining maximum permanence, and they provide a test formula. This information is at http://www.ilford.com/html/us_english/pdf/95065d.pdf. I give information on my web site on archival processing, with details on the procedures I utilize for fixing at http://unblinkingeye.com/Articles/Archival/archival.html.

-- Ed Buffaloe (edb@unblinkingeye.com), January 10, 2002.

After doing some checking with others I dropped the Ilford rapid fix process & went back to the older, normal two bath system. Some photographic chemists & researchers I spoke with told me the single film strength fix regimen would not fix all papers fully in the recommended time. They also stated the capacity of the single film strength bath was much lower than a two bath system of either film strength fixer or the older paper strength mix. So, I put the paper through the first bath of paper strength fix & then in a holding bath until a few have gathered or the printing session is done. Then I put them in the second fresh fix bath for the recommended time of 4 minutes. Then rinse, hypo clear & wash. I am looking at moving to the alkaline fixing system, two baths once again, so I can eliminate the hypo clearing & rinse clean in shorter time. I have been told the single bath system isn't an "all else being equal" deal and as such don't use it. I just want the prints to last & if it takes a bit more attention to them to assure this, I will do it.

-- Dan Smith (shooter@brigham.net), January 10, 2002.

I'm mired even further in the past. I've been using good 'ol Kodak powdered fixer since about 1970 and most of my prints from back then still look fine. Amazingly, my old RC prints from a few years later also look fine. If it ain't broke, don't *fix* it. (really bad pun) I still use the stuff today and can't see any good reason to change. It's also cheap and readily available. Never had any problem toning (selenium) either.

-- Conrad Hoffman (choffman@rpa.net), January 10, 2002.

I kinda expected a long line of "I can't trust that quick and dirty processing" type of responses.

For efficient fixing, you really need a good agitation. Two-bath system forces you to give at least some agitation when you move the print forward, so it's good. But if one blindly followed rapid fixing technique without taking the agitation and timing requirement seriously, then it's natural that he feels that two bath method is better. I'd rather give good agitation during fixation to minimize the time paper fiber and gelatin are wet. Minimum wet time is a very good thing for paper.

The Ilford's fixing test solution described in the document that Ed suggested is basically a toner that tones unfixed silver halides. Inadequatelly fixed films and papers are out of question. Since I tone all important prints in selenium, sulfide or selenium-sulfide toner, I know I'll catch if any of the print is not adequatelly fixed. However, the real danger, and one of the problem in image permanence is the complex silver ions produced during the early stage of fixation. This is as bad as and as hard to wash as fixing agents. Fixer exhaustion should be determined based on how quickly those complex ions are broken down in the fixer solution, instead of how long the fixer takes to dissolve the silver halides. (This is one of the reasons why you should double or triple the clearing time to determine film fixing time.) Either way, the way I deal with this issue is that I keep record for mixing and using chemicals. I mix my own fixer from scratch and I don't think it's worth testing silver concentration frequently to decide when to throw out.

If two-bath is not cumbersome, it's good. The second bath ensures to break down the complex silver ions even if the first bath didn't. Even when prints are fixed and washed properly, the stress to the gelatine and paper is minimized with carefully formulated modern rapid fixers without hardeners and minimal wet time required to process the paper properly. Manufacturer's recommended capacity is conservative for average prints, and it's not an abrupt threshold, so it is usually adequate to count surface areas processed.

This is a matter of preference, but it is best to use simple effective fixing system such as Ilford system, and follow that simple rule all the time. Unnecessarily cumbersome two-bath system only gives me a reason to become sloppy.

> Some photographic chemists & researchers I spoke with told me the single film strength fix regimen would not fix all papers fully in the recommended time. (quote from Dan Smith's posting)

This is probably true for non-rapid (sodium thiosulfate) fixers. This problem with non-rapid fixers is not solved by increasing the fixer strength either. With a rapid (ammonium thiosulfate) fixers, especially with that of neutral or slightly alkaline pH, this is not a problem. Published experimental data also indicates that ammonium thiosulfate washes out more quickly than sodium thiosulfate.

With regard to processing capacity, it should be noted that the ammonium thosulfate is so much more efficient in fixation that most rapid fixer has much less amount of ammonium thiosulfate in them. Since ammonium thiosulfate is stable in solution but unstable in dry form, most rapid fixers are sold in liquid concentrate. Pakaging, transportation, and added convenience may act together to push up the fixation cost per sheet, but chemical waste is actually less. Liquid fixer solutions are most stable for storage when they are diluted to working strength. So if you prefer, you can dilute the whole bottle in a big tank. This is very different from developers. (sulfites in fixers are preservative, but they act in a very different way as in developers.) Also, acid hardening fixers are least stable for storage.

Besides image permanence, some papers (especially ones with bright white base) changes its color as the wet time extends. This is another reason I minimize wet time.

I'm not telling those with long standing practice to change their way of processing. In short, proper use of rapid fixer has so much advantage that I think the convenience of one bath processing exceeds the benefit of two bath processing. The decision may be more of a matter of comparing the practical benefit and psychological benefit.

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), January 10, 2002.

Of course I do feel somewhat guilty about it and do ponder the TF-4 page of the Photographer's Formulary catalog every so often!

-- Conrad Hoffman (choffman@rpa.net), January 11, 2002.