Advise: single bath fixing for fiber paper? Bad idea?

brian steinberger said:

What are you guys thoughts on two bath fixing using hypam at 1:9? That's what I've been doing lately. One full minute in each bath. Then hypo clear for 5 minutes, wash for an hour.

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Brian,

This is essentially what I do (and have done for years). My fixing times are a bit longer for safety though, I use 1.5-2 minutes per bath. That said, I wash between fixes. If I were transferring directly to fix 2 from fix 1, I'd likely still want 1.5 min. per bath. I tone, and then hypo-clear for 5-10 minutes and then wash for minimum 60 minutes.

Hope this helps,

Doremus

Doremus Scudder said:

Mr Bill, You've made my case that there is no really convenient way currently available to test for dissolved silver at the levels you need for one-bath fixing

Seriously, if I had a densitometer, I might get some silver-estimating papers and try it out. However, the devil seems to be in the calibration. I'd have to come up with a way to dissolve silver compounds that the papers are sensitive to in the right amounts to accurately get control solutions...

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Hi, I've been away, sorry to be so late responding.

I spoke about how "we" used the silver estimating paper, but you don't have to make it so "inconvenient" if you don't want to. You don't have a densitometer, so you could evaluate the paper by eye. But you need a reference. You also need a calibration, but if you're already not being that finicky, it doesn't need to be so finicky, either.

Here's a possible method. You had indicated that you have previously used the test papers to find ~ 2 g/l silver; if you were ok with this then use the same thing as a starting calibration solution. Then mix the 2 g/l solution 50/50 with new fixer to get a 1 g/l solution. Repeat the procedure to get 0.5 g/l, and go on as far as you want.

Now that you have the test solutions, run the dip tests. You still need a comparator scale - the test papers are not stable enough to keep long term. One option is to use the printed reference already supplied with the silver estimating paper, just re-label it to fit your 30-second test results. Or print some sort of gradient image and cut out a small sample that closely matches each of your dip test results. Of course it won't be as precise or accurate as a densitometer-based system, but... if you were already satisfied with a visual dip test, why not continue to be satisfied? The main thing is that the sensitivity of the dip test is increased on the order of 5 times, or so.

FWIW the way we did the calibrations was to pull periodic samples from an electrolytic silver recovery system, "split" the samples (meaning that we keep one), and have them analyzed at a testing lab. One of our main uses was to screen for the end of a desilvering cycle. We could reliably identify, for example, a sample below 1/10 g/l, or one between 1/10 and 2/10 g/l silver.

This test method is really the "holy grail" of low cost silver concentration testing for processing labs looking at the first stage of a silver recovery operation.

Doremus Scudder said:

Brian,

This is essentially what I do (and have done for years). My fixing times are a bit longer for safety though, I use 1.5-2 minutes per bath. That said, I wash between fixes. If I were transferring directly to fix 2 from fix 1, I'd likely still want 1.5 min. per bath. I tone, and then hypo-clear for 5-10 minutes and then wash for minimum 60 minutes.

Hope this helps,

Doremus

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Great, thanks Doremus. Glad to know I'm ok. I will lengthen my times to 1 1/2 min each. I do see that Ilford recommends 1 1/2 min in each bath after digging in the tech sheets. Interesting though as single bath recommended time is 2 min at 1:9

The pros and cons for one and two bath fixing bath posts always intrigue me.

Now a days, I always use a one bath fixer (diluted at 1+9) in a Nova slot processor, leaving both RC and FB in the fixer for as shorter period as possible, followed by a soak in a washaid solution (FB only), followed by a good soak / wash in a few changes of tap water, with to date, no staining problems.

Now go back about 40 (yes, 40) years, when I was in my teens and just starting out in the darkroom. In photo books back then, it was recommended to dev, stop and fix as today and to then give the prints a quick rinse in water. After this, to put your FB prints (no RC in those days!) into a Sodium Carbonate (Washing soda powder / crystals) solution for about 10 minutes. After this, the prints would be left to soak in a shallow bath (as in bathroom bath) of water, agitating and changing the water occasionally, for about an hour. The result? Today I can look at the prints (when they pop up in various places around the house = a lax filing system ) and guess what? None of them have a single sign of any fading or staining on them at all. So, whenever I see posts like this, discussing the benefits of a two bath over a one bath etc., I sit back and relax whilst my prints soak in their water bath, with the only real difference being that they get their rinsing done in a slot washer rather than the bath itself, knowing that they will be fine for future viewing.

Terry S

Doremus Scudder said:

That said, I wash between fixes.

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Ouch, that makes me cringe from a silver-recovery standpoint. Granted this will virtually guarantee that the final fix tank never reaches a significant silver concentration, but it most likely will become significantly diluted with water. And a significant amount of your recoverable silver will end up in that intermediate wash, wherever it eventually goes.

If the total amount of silver is insignificant financially and is not being regulated, none of this much matters.

tezzasmall said:

The result? Today I can look at the prints (when they pop up in various places around the house = a lax filing system ) and guess what? None of them have a single sign of any fading or staining on them at all. So, whenever I see posts like this, discussing the benefits of a two bath over a one bath etc., I sit back and relax whilst my prints soak in their water bath, with the only real difference being that they get their rinsing done in a slot washer rather than the bath itself, knowing that they will be fine for future viewing.

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As I have occasionally said before, the main benefit to 2-bath fixing is to reduce the chemical cost. That's pretty much it if you ignore effluent regulations.

And even the regulations can be seen as simply another cost. A fair number of the posters here seem to haul their waste fixer to a "free" local "hazardous waste" collection where it is what ... incinerated? Of course, it's not really "free," it just looks that way to the user. A commercial finisher would be paying handsomely for this, so given some minimum volume, it's much cheaper to set up multi-stage fixing operations and control your effluent.

If you believe that usage of fixer is ultimately limited by the build-up of silver in the final bath, then it can be shown that fixer usage (and cost) can be cut by more than half, depending on what limits you think are important. Granted, these savings may be insignificant to hobbyists, it just depends on one's situation.

It's great that none of your older prints show fading or stains, but I wonder if this might be partly due to good storage conditions. For example, if they were displayed, exposed to light and the atmosphere, perhaps even higher humidity, then maybe they would have problems? It's hard to guess what "might have been."

Mr Bill said:

Ouch, that makes me cringe from a silver-recovery standpoint. Granted this will virtually guarantee that the final fix tank never reaches a significant silver concentration, but it most likely will become significantly diluted with water. And a significant amount of your recoverable silver will end up in that intermediate wash, wherever it eventually goes.

If the total amount of silver is insignificant financially and is not being regulated, none of this much matters.

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Mr Bill,

My work-flow is to fix to "commercial" standards during the printing session, i.e., a two-minute fix in rapid fixer, throughput <35 8x10s per liter. I then wash archivally. The prints that make the cut after that (I toss lots of them) are then collected and go to a toning session, which entails a soak, second fix in fresh fixer and then toning, hypo-clear and a >60-min. wash. I sometimes use the second fix for the first fix for a successive printing session, but often not. All fix now gets taken to a local photofinisher for silver recovery.

The levels of silver in my wash water shouldn't be significantly more than if I were using a one-bath method and fixing to "commercial" standards (40 8x10s/liter).

Note that Haist and others recommend an intermediate water rinse between first and second fix to prevent carry-over of dissolved silver compounds into the second bath. If drained well, there shouldn't be a problem with overly-diluting the second fix due to carry-over of water.

If so much recoverable silver gets lost in the wash water (intermediate or not), it would seem to make sense to have a post-fix rinse tray or some such, the contents of which would be added to the used fixer for silver recovery. Did you do any recovery of silver from wash water?

Best,

Doremus

Doremus Scudder said:

Did you do any recovery of silver from wash water?

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Hi, yes, at one time we (the large chain outfit where I spent a lot of years) did silver recovery from wash water. And in fact, I personally oversaw the purchase, installation, and operation. I should probably say a little about myself, which I have typically avoided online. I started out as fundamentally a photographer, but at some point took a "temporary" excursion into lab work when color still seemed a sort of black art. I figured to stick with it as long as I was learning new things, which kept going on, and I eventually found the tech work more interesting and challenging than actually shooting. Being that it was a very large outfit, but, shall I say, frugal, I was able to get involved, and gain deep experience in many areas, with tremendous technical support from all the major photo manufacturers.

I spent a number of years as the Quality Control Dept manager, including the time period when US effluent regulations became stringent. My department handled those things, and I personally worked out a lot of the basic silver control strategies and system designs.

Anyway, our wash water system was custom built by CPAC, in NY state, based on research published by Rami Mina (as I recall) of Kodak. It used a couple of ion-exchange columns (Rohm & Haas IRA 400, I think) to "collect" silver, which was later stripped off by the "mass action" of a thiosulfate solution - essentially "fixer," which was run through an electrolytic silver recovery unit. In the meantime, a "reconditioning" bath was pumped through the columns, and they were returned to service.

Ultimately the system was not very successful. When the resin was fresh it worked really well, and we could easily meet the regulatory limits, which were something like 2/10 mg silver per liter. But on multiple stripping and reconditioning cycles, the resin gradually lost capacity and began to "leak" higher concentrations of silver. Mina's original research was necessarily done on a smaller (bench?) scale, whereas our system ran 50 gal/min; things like resin life didn't scale up well in the real world.

Eventually we changed our strategy to rely mainly on carefully "tuned" multi-stage fix or blix with countercurrent replenishment flow. The idea was to keep the "main" wash water from ever reaching the regulatory limits, and the solutions that had to be desilvered could use less-sophisticated technology. There was more to it than I've said, but it was very successful for many years, easily and reliably meeting the effluent limits.

When I make suggestions in these areas, they're usually based on my practical experience and understanding. You might note that I tend to put in conditions, like "if your effluent is regulated," to be clear what I am recommending. From a strictly financial viewpoint (ignoring fines) it's almost never worth going after low concentration silver. This is generally done only to meet regulatory limits.

Doremus Scudder said:

Note that Haist and others recommend an intermediate water rinse between first and second fix to prevent carry-over of dissolved silver compounds into the second bath. If drained well, there shouldn't be a problem with overly-diluting the second fix due to carry-over of water.

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Hi, I have to say that I don't see anything good about this idea. I have great respect for Haist, but in truth "we" (on behalf of a former employer) never saw him, via his books, as a useful source of information on silver recovery or effluent control (technical papers by Austin Cooley, of Kodak, were the best). When he wrote "Modern Photographic Processing," I don't think that the tight environmental regulations, in particular for silver in effluent, were in effect. Now, if the value of your silver is too low to be worth recovering, and if your effluent is not regulated, then this might be OK advice. But I have to admit that I don't recall ever reading it.

My first question would be, "why water?" Since I don't see any useful purpose, I'd say, "why not another fixer tank in the middle, instead of water?" If you want (or need) to recover silver, this appears better in every respect, especially if you replenish it (use a countercurrent flow method). It minimizes dilution of the last fixer tank, keeps silver concentration low in the last fix tank, plus it keeps most of the silver in the recoverable stream. (You don't lose silver to that intermediate water wash). Now, if the silver is NOT worth recovering, it may be a different story, but I'm not sure.

As a note, I have had C-41 cine processors set up with three-stage fixing, using countercurrent flow replenishment (I wanted to use four stages, but our machine frames didn't have enough space). The scheme worked pretty well - we had to keep replenishment rates higher than we wanted to limit the silver carryout loss to wash water, but doing this meant that we didn't have to use wash water recovery techniques. A small added chemical cost saved a lot of extra work and cost. At any rate, I have pretty substantial experience in these areas.

NOTE: something that I should mention is that the vast majority of my experience is in the color neg systems, meaning that the paper was RC. Not fiber paper, which was the original subject of this thread. I THINK that the same principles hold, but it is possible that I'm overlooking something pertinent.

Doremus Scudder said:

Mr Bill,

My work-flow is to fix to "commercial" standards during the printing session, i.e., a two-minute fix in rapid fixer, throughput <35 8x10s per liter. I then wash archivally. The prints that make the cut after that (I toss lots of them) are then collected and go to a toning session, which entails a soak, second fix in fresh fixer and then toning, hypo-clear and a >60-min. wash. I sometimes use the second fix for the first fix for a successive printing session, but often not. All fix now gets taken to a local photofinisher for silver recovery.

The levels of silver in my wash water shouldn't be significantly more than if I were using a one-bath method and fixing to "commercial" standards (40 8x10s/liter).

Note that Haist and others recommend an intermediate water rinse between first and second fix to prevent carry-over of dissolved silver compounds into the second bath. If drained well, there shouldn't be a problem with overly-diluting the second fix due to carry-over of water.

If so much recoverable silver gets lost in the wash water (intermediate or not), it would seem to make sense to have a post-fix rinse tray or some such, the contents of which would be added to the used fixer for silver recovery. Did you do any recovery of silver from wash water?

Best,

Doremus

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The intermediate wash water allows one to have a holding place so that the prints can have a holding area and so that over fixing is avoided.