Formulary Fixer Test, film, paper, testing, capacity and times.

[jstraw]

Yes, all of that...

I think that in the past I've been guilty of discarding un-exhausted fixer. I want to use it to exhaustion and think about silver recovery.

If I use it to exhaustion, as determined by testing, will I be able to count on using the same fixing times for film and and paper right up to the point of exhaustion or do I need to make any adjustments as I approach that point?

I'm assuming I can track how many prints/sheets/rolls it takes to reach exhaustion for film and for 1st and 2nd print trays to establish a baseline so I can track how close to typical exhaustion I am and to then test.

What insights can you folks share on this subject?

 

[removed account4]

hi michael

an easy way to determine if your fixer is used to capacity, or nearly to capacity ( i am sure some will tell me i am wrong )
is to do a clip test ...
take your favorite film and open it in daylight in your darkroom so it is totally exposed to light ...
clip off about 1 square inch of film.
put that film in your fixer ( lights on ) and watch the clock. when it clears to base note the time.
double that time for your film fix time .. so if it is 30 seconds ... your fix time for this film is 60 seconds.
split it between 2 baths ... 30 seconds in each ...
paper .. fix it to your manufacturer's recommendations ... split it again between your 2 baths ...

when your fixer takes 2x the original "fresh fix" clip test ( so 1 min in our example ) your fixer is spent and shouldn't be used anymore ...

remove #1 for recovery ( or hauling or whatever your situation is ) make your #2 your new #1 and make a NEW second bath.
do your clip test whenever you process film / print so you know if you are spent &c ..

the thing with 2 baths is the first bath does most of the heavy lifting, and bath 2 does clean-up ...

"the drops" ( like edwal's hypo check ) will give you a false reading, unless you are using edwal's fixer, and often times
people don't really take out 1oz put a the drops in and swirl it to see if it is reabsorbed so they get a false reading that way too ...

the thing about the fix test is to use the same film you always use so the silver content of the film won't be different between the test and your film ...

good luck !
john

 

[Gerald C Koch]

I agree with John. The best way is to keep track of the amount of film/paper put through a bath. The check solution is realy not that accurate.

 

[jstraw]

I'm talking about Photo Formulary's Fixer Test, not those cheapo drops.

So I understand, you're saying use 2x time-to-clear with film to test exhaustion of fixer used for prints as well as for fixer for film, yes?

Thanks...

 

[Gerald C Koch]

It really doesn't matter who makes the test solution. By its very nature the test is not that accurate. Part of the reason is that it requires the user to make a rather subjective decision. PF in their directions should give the recommended capacity for the fixer. As fixer nears the end of its useful life it becomes harder and harder to remove silver complexes. This can cause degradation of prints and films which may not be immediately visible. Film and paper are expensive, fixer is cheap. Scrimping on fixer is a foolish economy.

 

[Mr Bill]

If I use it to exhaustion, as determined by testing, will I be able to count on using the same fixing times for film and and paper right up to the point of exhaustion or do I need to make any adjustments as I approach that point?

I think the standard approach would be to find a fixing time that is acceptable as your system becomes "exhausted," then always use that time. When you have fresher chemicals, the fixing time is on the long side, but who really cares?

The trickier thing is deciding what "exhaustion" actually is. The easiest thing is to follow the procedure spec'd out by the manufacturer of your materials, assuming you can find such a thing. Otherwise, the responsibility falls on you.

That said, I pretty much agree with John (and Gerald). The only thing I'd do differently is to check the silver concentration in the "clean" tank. I'm not up to date on this, but "silver estimating papers" used to be commonly available. These were typically used for roughly 1 to 10 grams/liter silver. You should check other sources for actual recommendations, but my fuzzy memory says that under about 1.5 g/l for film, and under about 1/2 g/l for fiber paper is fine for high-grade processing. Whenever either of 1) first fix time gets too long, or 2) last fix gets too much silver, then you bring in some fresh fixer and shift the tanks.

Counting the volume of material processed is a little iffy for B&W, since it actually depends on how much silver was developed. If you do mostly high key photos, then the great majority of the PAPER's silver must be removed in the fixer, whereas mostly black photos will barely use up the paper fixer. (For color materials, it doesn't matter since ALL of the silver ends up in the fixer.)

If you're interested in more details, I talked about replenished fixer systems in this thread, starting with post #31. (there was a url link here which no longer exists) (I don't think you'll get any practical use out of it, but you might say "Oh, now I see why they're doing that.")

ps: Gerald's latest post, "fixer is cheap," is right. In real-world commercial processing, the main reason for multi-stage fixing is to maximize silver recovery and to help meet environmental regulations.

 

[removed account4]

sprint systems of photography makes developer, stop, fix and fix remover ( and other stuff ) for both film and paper. they call their chemistry a system because
when the stop bath indicates it indicates when EVERYTHING is spent ... their fixer is high capacity "speed fixer" ... you may write or call them
to see if using their stop+fix instead of all 4 if you like using other chemistry? to see if the stop will still indicate for the fixer. it might make your life easier
because you don't have to deal with tests which may be useful, confusing or a PITA ....
not saying not to use the formulary-stuff but i used it years ago and it had a scent i couldn't get used to, so i went back to using sprint fixer.
its a liquid concentrate, lasts and lasts and doesn't reek ... some of their chemicals smell like vanilla too ..

 

[jstraw]

It really doesn't matter who makes the test solution. By its very nature the test is not that accurate. Part of the reason is that it requires the user to make a rather subjective decision. PF in their directions should give the recommended capacity for the fixer. As fixer nears the end of its useful life it becomes harder and harder to remove silver complexes. This can cause degradation of prints and films which may not be immediately visible. Film and paper are expensive, fixer is cheap. Scrimping on fixer is a foolish economy.

I understand your point and don't disagree. But I also view water conservation, minimal use of pollutants and maximizing the capability for silver recovery as important. It's not about the cost of fixer.

 

[jstraw]

The only thing I'd do differently is to check the silver concentration in the "clean" tank.

I'm not sure what you mean by "clean tank."

 

[Doremus Scudder]

Michael,

Fixer doesn't have an exhaustion point that's really easy to nail down. I depends more on the amount of residual silver you are willing to live with in your film/paper and the amount of safety margin you want in your fixing regime so that you don't use fixer that is too full of unwanted silver compounds to fix with.

Ideally, we could easily measure the amount of dissolved silver in a fixing bath accurately down to the small levels that are needed (e.g., 0.2g/l for optimum permanence for fiber-base prints). Unfortunately, this is not practical for the typical darkroom worker. This is why you need an adequate safety factor (read, you don't really want to work at the edge of exhaustion; it's just too risky if you want optimum permanence).

My solution to get the most of my fixer while still ensuring optimum fixing is to use two-bath fixation whenever possible, even for film.

For film, do a clip test on your first bath before each batch. I triple the time instead of doubling it; some modern films do take longer to fix due to the silver iodide in the emulsion, and a safety factor for film can't hurt, since it is on an impermeable base. This time I divide between the two baths. When the clearing time for the clip test is double that in fresh fix, bath 1 is sent to silver recovery and bath 2 takes its place. If you develop film regularly, then you can keep the system going for the full seven changes before the fixer is too old (see below).

For fiber-base prints, don't take any chances, especially if you want optimum permanence. First, try not to overfix; use a minimum time and a safety factor on capacity. I use throughput as a guide and discard bath 1 somewhat before the recommended capacity is reached just to be sure. You'll still have a lot of silver in bath 1 to recover if you do this. It's just much better to err on the side of caution here IMO. I use 36 8x10 per liter as a maximum throughput (slightly less than Ilford's recommendation). If you use another fixer, read the manufacturer's recommendation. Again, when your capacity for the first bath is reached, replace it with the second. This can also go through seven changes till you should discard both baths and start over. Or discard when the maximum age of the fixer working solution has been reached, whichever comes first. Ilford recommends the following for fixer lifespan: 6 months in full tightly capped bottles, 2 months in a tank or dish/tray with a floating lid, 1 month in a half full tightly capped bottle or 7 days in an open tray.

Test your system at the beginning and then regularly thereafter for residual silver using the Kodak ST-1 residual silver test to make sure your fixing to an acceptable standard (and do the HT-2 residual hypo test while you are at it to test if you are washing adequately as well). Both these tests are available from the Formulary (with different proprietary names, but the same tests).

The above will give you peace of mind, get the most out of your fixer and ensure you aren't sending unused or partially used fix to silver recovery.

Best,

Doremus


www.DoremusScudder.com

 

[Photo Engineer]

Lots of long answers here but I have found that the retained Silver test and the retained hypo test are the best. The Formulary uses Kodak formulas for making them up. The exhausted fixer test is virtually useless especially when using papers. Testing for 2x clearing time in film is quite useful as well.

I spent years on the subject of fixers and find the subject fascinating.

Oh, the Formulary sells a full line of film and paper solutions for development, stop, fixing and post wash testing. I have never used a hypo eliminator or any such was aid. They are virtually useless and increase the pollution factor.

PE

 

[jstraw]

Isn't it a trade off? If I don't use a wash aid, won't I have to use much more water to wash out fixer?

 

[Photo Engineer]

It is a trade off between dumped salts from the wash aid and the increased water with a small amount of hypo and silver complexes. However, in the larger view, you have to get rid of the hypo and silver complexes so it boils down to the pollution "demand" imposed by the wash aid.

And, modern day RC papers take less washing anyhow.

For those who yelp about FB papers, they are more heavily calenared nowdays and thus the papers are less porous. If you don't believe me, check a modern FB such as Ilford MGIV and comapre it with a 20 or 40 year old sample of say Kodabromide. There is quite a difference.

PE

 

[jstraw]

Michael,

Fixer doesn't have an exhaustion point that's really easy to nail down. I depends more on the amount of residual silver you are willing to live with in your film/paper and the amount of safety margin you want in your fixing regime so that you don't use fixer that is too full of unwanted silver compounds to fix with.

Ideally, we could easily measure the amount of dissolved silver in a fixing bath accurately down to the small levels that are needed (e.g., 0.2g/l for optimum permanence for fiber-base prints). Unfortunately, this is not practical for the typical darkroom worker. This is why you need an adequate safety factor (read, you don't really want to work at the edge of exhaustion; it's just too risky if you want optimum permanence).

My solution to get the most of my fixer while still ensuring optimum fixing is to use two-bath fixation whenever possible, even for film.

For film, do a clip test on your first bath before each batch. I triple the time instead of doubling it; some modern films do take longer to fix due to the silver iodide in the emulsion, and a safety factor for film can't hurt, since it is on an impermeable base. This time I divide between the two baths. When the clearing time for the clip test is double that in fresh fix, bath 1 is sent to silver recovery and bath 2 takes its place. If you develop film regularly, then you can keep the system going for the full seven changes before the fixer is too old (see below).

For fiber-base prints, don't take any chances, especially if you want optimum permanence. First, try not to overfix; use a minimum time and a safety factor on capacity. I use throughput as a guide and discard bath 1 somewhat before the recommended capacity is reached just to be sure. You'll still have a lot of silver in bath 1 to recover if you do this. It's just much better to err on the side of caution here IMO. I use 36 8x10 per liter as a maximum throughput (slightly less than Ilford's recommendation). If you use another fixer, read the manufacturer's recommendation. Again, when your capacity for the first bath is reached, replace it with the second. This can also go through seven changes till you should discard both baths and start over. Or discard when the maximum age of the fixer working solution has been reached, whichever comes first. Ilford recommends the following for fixer lifespan: 6 months in full tightly capped bottles, 2 months in a tank or dish/tray with a floating lid, 1 month in a half full tightly capped bottle or 7 days in an open tray.

Test your system at the beginning and then regularly thereafter for residual silver using the Kodak ST-1 residual silver test to make sure your fixing to an acceptable standard (and do the HT-2 residual hypo test while you are at it to test if you are washing adequately as well). Both these tests are available from the Formulary (with different proprietary names, but the same tests).

The above will give you peace of mind, get the most out of your fixer and ensure you aren't sending unused or partially used fix to silver recovery.

Best,

Doremus


www.DoremusScudder.com

I appreciate your help. I have a question about your recommendation for cycling 1st and 2nd fixer baths. You say "when your capacity for the first bath is reached, replace it with the second. This can also go through seven changes till you should discard both baths and start over. "

When the previous second bath becomes the new 1st bath, what is the capacity? Surely it doesn't see the same 30 8x10s the original 1st bath got. Can you clarify?

Thanks.

 

[Mr Bill]

...check the silver concentration in the "clean" tank.

I'm not sure what you mean by "clean tank."

From your first post, I've taken it that you are using 2-bath fixing, that is, a first tank followed by a second tank. Since the first tank collects most of the silver, I call it the "dirty" tank. The second tank, with a relatively small amount of silver, I call the "clean" tank. (In the industry, the normal nomenclature would be "fix-1" and "fix-2").

The reason I suggest checking the silver content of the final fix tank (the "dirty" tank, fix-2,etc.), is that you normally want to keep this below a certain spec concentration. If you look for "exhaustion" in the first fix bath, you really don't know much about the silver concentration in the final fix tank. It depends largely on how much solution carryover you have; this is the amount of solution the wet film or paper takes along with it. If you don't use squeeges between all the tanks, you probably can't "exhaust" the first fix bath before the second bath exceeds fairly low silver limits.

 

[jstraw]

From your first post, I've taken it that you are using 2-bath fixing, that is, a first tank followed by a second tank. Since the first tank collects most of the silver, I call it the "dirty" tank. The second tank, with a relatively small amount of silver, I call the "clean" tank. (In the industry, the normal nomenclature would be "fix-1" and "fix-2").

The reason I suggest checking the silver content of the final fix tank (the "dirty" tank, fix-2,etc.), is that you normally want to keep this below a certain spec concentration. If you look for "exhaustion" in the first fix bath, you really don't know much about the silver concentration in the final fix tank. It depends largely on how much solution carryover you have; this is the amount of solution the wet film or paper takes along with it. If you don't use squeeges between all the tanks, you probably can't "exhaust" the first fix bath before the second bath exceeds fairly low silver limits.

I think you're telling me to pay the most attention to the second fix' silver content. It's a little confusing because it seems as though you just referred to the 1st fix as the dirty tank then the second fix as the dirty tank.

 

[Photo Engineer]

You must remember that it is almost impossible to check a tank for Silver content. This is especially true when using the fix for paper.

The most reliable test is "time to clear". Select a 35mm film type (whether you are using paper or not) and cut an unexposed roll into 2" pieces. Using fresh fix, determine the clearing time. Now, every time you make a run, do the same with another piece of film. When the clearing time is approaching 2x the original time, that fix (first or second "tank, tray or whatever") is shot.

PE

 

[jstraw]

You must remember that it is almost impossible to check a tank for Silver content. This is especially true when using the fix for paper.

The most reliable test is "time to clear". Select a 35mm film type (whether you are using paper or not) and cut an unexposed roll into 2" pieces. Using fresh fix, determine the clearing time. Now, every time you make a run, do the same with another piece of film. When the clearing time is approaching 2x the original time, that fix (first or second "tank, tray or whatever") is shot.

PE

This makes the most sense to me. Presumably, the first tray will be shot first. The second tray will become the new first tray and so-on. Is that correct?

Do you see an advantage to two tank film fixing?

 

[Mr Bill]

I think you're telling me to pay the most attention to the second fix' silver content. It's a little confusing because it seems as though you just referred to the 1st fix as the dirty tank then the second fix as the dirty tank.

You're right - I messed up my wording. I meant to call the second tank the "clean" tank.

 

[Photo Engineer]

I have never felt that I had to use 2 "tank" fixing except in production situations. It is just too much hassle to me.

And, BTW, for good prints HQ and Metol retention are things to consider. As you re-use fix, these build up in the fix and there is NO test for them. So, be careful.

PE

 

[jstraw]

Ok, I won't go nuts. If I don't exceed 2x TTC, do you think I'll be ok?

I want to thank you all for your input.

 

[Mr Bill]

You must remember that it is almost impossible to check a tank for Silver content. This is especially true when using the fix for paper.

The only sensible way I know to do this is with the silver-estimating paper I mentioned. Unfortunately the typical test papers are not good at identifying silver levels much below about 1 g/l. Kodak once published a method to increase the sensitivity with a 30-second immersion, but it required "calibration" using a lab that could run silver analyses. (I don't think the method is published anymore.)

The most reliable test is "time to clear". Select a 35mm film type (whether you are using paper or not) and cut an unexposed roll into 2" pieces. Using fresh fix, determine the clearing time. Now, every time you make a run, do the same with another piece of film. When the clearing time is approaching 2x the original time, that fix (first or second "tank, tray or whatever") is shot.

I agree completely with this test to find when fixer "is shot." My issue is this: if you are trying to keep a low silver level in the final fix tank, say under 1/2 g/l, I doubt this test will show it. (I'm guessing, as I've never done fix-time vs silver content tests, but I'm very doubtful.)

 

[Mr Bill]

I have never felt that I had to use 2 "tank" fixing except in production situations. It is just too much hassle to me.

Hi, my main experience has been in production situations, but primarily color neg and print. From my considerable experience with effluent control, I can say that it would be extremely difficult for a lab to get silver in the effluent under, say 2/10 milligram/liter (not an unusual regulated number), without using multi-stage fixing. In fact, this is why "washless" mini-labs were introduced; low flow counter-current "rinses" were used, such that the total volume was small enough that one could afford to have a waste handler take it over.

If one is small enough that they are unregulated (or perhaps no one is looking at your effluent), and the chemical costs are insignificant, then it's probably not an issue.

And, BTW, for good prints HQ and Metol retention are things to consider. As you re-use fix, these build up in the fix and there is NO test for them. So, be careful.

I don't have any useful knowledge about the effect of these. Aside from what you (PE) say, about the only thing I'd have to go on would be Kodak literature describing a two-stage fixing system. In my mind, this is an endorsement of the system. (At least when Kodak sold B&W papers.) If one ignores any HQ/Metol retention issues, I would imagine that the same modeling methods I've successfully used for silver in color systems would be equally valid for B&W.

 

[Photo Engineer]

Bill, a Silver estimating solution is better than ANY paper. Just one drop on the border of a print will prove my point.

I have worked with systems capable of zero pollution and unrestrained pollution and have compared both from the POV of impact and cost. So, I am glad that you can agree with me on some points.

BTW, the reference to HQ retention is in Haist for those interested.

PE

 

[jstraw]

PE, do solutions like Agfa's Sistan deal with the residual silver in prints in a meaningful way?