Fixer Effective Lifespan ?

[MattKing]

As for capacity, this is somewhat dependent upon specific fixer, but generally about 100 8x10 equivalents
135 mm or med format roll = 1; 8x10 print = 1

Per gallon of working solution, I believe.
Or 26 per litre.

 

[wiltw]

Per gallon of working solution, I believe.
Or 26 per litre.

Confirming 'per gallon'...stupid me to not have included that in my earlier post.

 

[koraks]

Boy, and I thought I was a pessimist.

 

[Doremus Scudder]

Boy, we really need a "Fixer Best Practices" sticky thread where authoritative information on fixer shelf-life, capacities and proper disposal are available.

As for disposal of used fixer, the best I have found is to locate a working film photo lab and see if they will take your used fixer for silver recovery and subsequent disposal. Most are happy to do this if you let them keep the reclaimed silver. That's a small price to pay for doing things right. If that's not available, check with your local authorities. Often, small amounts of silver-laden fixer from non-commercial home processing are okay to dump into the sewer system. The silver then gets converted to stable silver-sulfide compounds at the treatment plant. Home silver recovery is possible, but not practical for a lot of us. Taking used fixer to a HazMat facility is my last choice; they won't recover silver and will spend a lot of energy incinerating your used fix.

As for capacities: First, read the manufacturer's instructions (Ilford has particularly good tech sheets on their fixers), or the capacity info from the formulators (there's a lot of info from Kodak and others about both conventional and rapid fixers out there). There are often different capacities given for "general" or "commercial" standards than for "archival" or "optimum permanence." If your goal is to make and sell prints made on fiber-base paper, processing for optimum permanence is really best practice. This means that fixer capacity is rather low, about 10 8x10-inch prints per liter of fix with a one-bath regime. A two-bath regime will double this and is more economical, but needs more space and an extra step. Using a wash-aid is indispensable for optimum-permanence processing of fiber-base prints

For film, the clearing test works well and is reliable. Test a piece of film with fresh fixer for clearing time. Best is to put a drop of fixer on the film, wait 30 seconds and then immerse the whole test strip in the fixer while watching carefully. Note the time when the time it takes for the area surrounding the drop to match the drop-area in transparency. This is the base-line clearing time for that film/fixer/dilution combination. Fixing time for film is then minimum twice the clearing time (I like longer). When the clearing time reaches twice that in fresh fixer, the fixer should be discarded. Note that if your save your fix and are determining your fixing time with a clearing-time test that you need to do a new clearing-time test before subsequent batches of film since the clearing time will be longer in used fixer. To avoid doing this, I like to fix my film for four times the clearing time in fresh fixer. This ensures that I have at least twice the clearing time in fixer that is just about exhausted.

Be aware that fixers for film should not be used for fixing prints. Also, be aware that fixers for film and RC papers can be used longer that fixers for fiber-base papers. Both film and RC papers will tolerate a much higher level of dissolves silver compounds in the fixer than fiber-base papers can. Fiber-base papers need fairly fresh fixer to do the job; for optimum permanence, very little dissolved silver can be in the (last) fix. A two-bath regime or frequent mixing of new fix with a one-bath regime is necessary.

Keep in mind that the "Hypo Check" / FT-1 potassium iodide check is not really that sensitive and maybe not ideal for optimum-permanence processing of fiber-base prints (unless you use it just for bath 1 of a two-bath fixing regime). Better is to test your own particular workflow for throughput using the sulfide ST-1 or the selenium toner tests for residual silver (along with the HT-2 test for adequate washing). Once you've determined the limits of your regime and added a nice safety buffer, you can then just test "last print though" to keep an eye on the process.

Since adequate fixation is dependent on the amount of dissolved silver in the fixer, the capacity for any given material and level of fixation is not affected by fixer dilution. Fixer dilution will affect the speed of fixation; the build-up of silver compounds in the fixer determines when the fixer will no longer fix adequately and needs to be discarded.

Fixers will go bad due to oxidation and sulfuring-out. Acidic rapid fixers are prone to this. "Plain-hypo" fixers also have a rather short working life and should not be stored for long periods.

There's a ton of info on this site, the LF fora and from manufacturers like Ilford, Kodak, et al., not to mention lots of books and websites on photo processing out there. There's really no excuse for not knowing how to best use your fixer of choice, how long to store it, what the capacities are, etc.

Best,

Doremus

 

[john_s]

....... The silver then gets converted to stable silver-sulfide compounds at the treatment plant...........

Doremus

Probably happens before its arrival at the treatment plant: no shortage of sulphur-containing compounds in the sewer!

 

[grat]

If you speak with police, fire, emt and insurance statisticians they will tell you most accidents occur within a mile of your house

That's why I moved.

 

[AgX]

Well I prefer not to dump it down the drain. If at all possible, I would like to try and recover the silver from the spent fixer. Worst case scenario, for me at least, I just submit the fixer to the city for proper processing and silver recovery.

I doubt You can deplete spent fixer for silver as good as a sound silver recovery facility. (But these become more rare.)

So, from an ecological perspective (keeping silver ions out of the environment) it likely is better to bring the spent fixer in at a municipal collection.

 

[AgX]

Often, small amounts of silver-laden fixer from non-commercial home processing are okay to dump into the sewer system. The silver then gets converted to stable silver-sulfide compounds at the treatment plant.

This "stable Silver" (e.g. Ag2S) then ends in the facility's sludg. And this may end on farmland, where the Silver may be dissolved again in the soil.

 

[albada]

Be aware that fixers for film should not be used for fixing prints.

I've read this elsewhere, and was wondering: What bad thing will happen if the same working solution of fixer is used for both film and paper? Will the film's magenta sensitization dyes in the fixer impart a magenta cast to prints? That a wild guess because I don't know.

Anyway Doremus, thanks for posting all that information. It's good to see it in one place.

 

[MattKing]

For clarity, I think that Doremus is saying fixers for film should not be re-used for fixing prints. You can use the same type of fixer for both purposes.
There is a fair amount of stuff that used fixer can pick up from film, including gelatin.

 

[koraks]

This "stable Silver" (e.g. Ag2S) then ends in the facility's sludg. And this may end on farmland, where the Silver may be dissolved again in the soil.

Around here sludge is incinerated. The years of carting it out onto some kind of field are long gone. I don't think in the US it's legal anymore either.

 

[BMbikerider]

I am late in replying to this topic of how long fixer lasts - however. In all of 52 years of using darkroom chemicals I have NEVER seen any information which has been proven correct that fixer has a life expiry date. However how long it lasts in use is a different matter, that will be governed by how much film/paper you put through the dilution.

I think the length of time given out by the manufacturers is a safeguard for them against litigation should someone make a mistake which costs the user money. It will also boost their sales!

The old standard maxim was test it at the beginning before any exposed/developed films were fixed by using a small piece of undeveloped film and see how long it took to clear the film and then double the time. During the life of the 'mix' periodically test the dilution with a similar piece of film and when the initial time to clear the film is doubled, then it is time to dispose of it and mix some new. This does mean you will have to keep notes which some for whatever reason may feel is an arduous task.

I have used the 'clearing time' test for as long as I knew about it back in the 1960's when I also worked in a police scenes of crime darkroom.

In the case of paper where you cannot see the 'clearing' time, they usually give a set area of film which will be the maximum that a given quantity of paper should be put through the same bath. I believe this is a quite reasonable way of working. What they don't say is, if there is any difference between resin coated paper and fibre based. With fibre I would be more cautious because some of the fixer the will be absorbed into the paper base and 'may' be more difficult to remove when washing.

There was also a double fixing technique used by some where a new fixer bath was used followed by one that had served a 'half life' but to to be honest it never really caught on. It was supposed to be more economic but I could not see their logic.

 

[Doremus Scudder]

I've read this elsewhere, and was wondering: What bad thing will happen if the same working solution of fixer is used for both film and paper? Will the film's magenta sensitization dyes in the fixer impart a magenta cast to prints? That a wild guess because I don't know.

Anyway Doremus, thanks for posting all that information. It's good to see it in one place.

I believe that fixing by-products from fixing film, specifically iodides, but maybe some others, tend to inhibit proper fixation of papers, or tend to get stuck in the the paper base of fiber-base papers. I'm not exactly sure, but I'm certain that the caveat comes from good sources.

For clarity, I think that Doremus is saying fixers for film should not be re-used for fixing prints. You can use the same type of fixer for both purposes.
There is a fair amount of stuff that used fixer can pick up from film, including gelatin.

To clarify: fixer that has been used for fixing film shouldn't be used for fixing prints. Certainly, the same brand of fixer can be used for both film and prints, just don't use fixer for prints that's already been used for fixing film.

Doremus

 

[MattKing]

In all of 52 years of using darkroom chemicals I have NEVER seen any information which has been proven correct that fixer has a life expiry date. However how long it lasts in use is a different matter, that will be governed by how much film/paper you put through the dilution.

You are very fortunate if you have never had old, unused fixer deteriorate. The "normal" acidic rapid fixer is actually quite prone to sulfuring out, which makes it unsafe for your film or prints to use.
You are correct that the time estimates - manufacture supplied or otherwise - are unreliable. Under similar conditions, I have had similar fixer last very different lengths of time before deterioration occurred.
Unused fixer concentrate does appear to last longer if it is unopened, but the response is also variable.
And as for two bath fixing, it does provide better economy if one is fixing to the higher standards required for archival processing. If one's target is the lower standard of general commercial processing, there is little benefit.

 

[Doremus Scudder]

I am late in replying to this topic of how long fixer lasts - however. In all of 52 years of using darkroom chemicals I have NEVER seen any information which has been proven correct that fixer has a life expiry date. However how long it lasts in use is a different matter, that will be governed by how much film/paper you put through the dilution.

I think the length of time given out by the manufacturers is a safeguard for them against litigation should someone make a mistake which costs the user money. It will also boost their sales!

The old standard maxim was test it at the beginning before any exposed/developed films were fixed by using a small piece of undeveloped film and see how long it took to clear the film and then double the time. During the life of the 'mix' periodically test the dilution with a similar piece of film and when the initial time to clear the film is doubled, then it is time to dispose of it and mix some new. This does mean you will have to keep notes which some for whatever reason may feel is an arduous task.

I have used the 'clearing time' test for as long as I knew about it back in the 1960's when I also worked in a police scenes of crime darkroom.

In the case of paper where you cannot see the 'clearing' time, they usually give a set area of film which will be the maximum that a given quantity of paper should be put through the same bath. I believe this is a quite reasonable way of working. What they don't say is, if there is any difference between resin coated paper and fibre based. With fibre I would be more cautious because some of the fixer the will be absorbed into the paper base and 'may' be more difficult to remove when washing.

There was also a double fixing technique used by some where a new fixer bath was used followed by one that had served a 'half life' but to to be honest it never really caught on. It was supposed to be more economic but I could not see their logic.

Powdered fixers (i.e., conventional, sodium-thiosulfate-based fixers) like Kodak fixer have a really long (maybe indefinite) shelf life if the package is not damaged and the storage conditions are favorable. Once mixed from the powder into a stock solution, oxidation slowly begins to take its toll and eventually the sulfur will precipitate out. The same happens with working solutions of fixer, only faster. That's why Kodak and others give a working life for these solutions based on how they are stored (full bottle, partially-full bottle, open tray, etc.). Allow me to quote from post #28 above:

"Kodak Darkroom data guide has shown fixer to have the following storage life, depending upon container:

• working solution in tray: 1 week
• working solution in gallon tank: 1 month
• stock solution in stoppered bottle: 2 months"

Rapid fixers sold in liquid form that are acidic (e.g., Ilford Rapid Fixer) have a limited shelf life even in concentrate form. If stored too long the sulfur will precipitate out. This will eventually happen even with a full, unused jug of concentrate. It's happened to me (took about five years, though...).

Rapid fixers also have similar storage limits to conventional fixers. Ilford's tech sheet for their Rapid Fixer states:

"WORKING SOLUTION LIFE ...
Unreplenished ILFORD RAPID FIXER working strength solutions should last for up to:-
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.
7 days in an open dish/tray."

Now, I'm sure these and the above recommendations from Kodak and Ilford are on the conservative side. Still, they are evidence that working solutions of fixer will degrade over time due to oxidation regardless of how much they have been used. I've tossed too many batches of sulfured-out fixer to dispute this.

As you mention, the clearing-time test is a good way to keep tabs on fixer capacity for film. For papers, throughput, based either on the manufacturers' recommendations or your own testing, is the most practical for low-volume processors. Keeping an eye on throughput together with not exceeding the recommended storage life for working solutions should guarantee that your prints are fixed adequately.

The "double-fixing technique" you mention is likely just two-bath fixing, where a first bath does most of the work and the fresher second bath finishes the job. This can double the capacity of fixers for fiber-base prints (film and RC papers too, but the practice seems most-used with fiber-base papers). It's even more economical when, after the capacity of the first bath has been reached, the second fixer is promoted to bath one and a fresh second bath is mixed. This cycle can be repeated 4-5 times before both baths need to be mixed fresh. I, and many others, use two-bath fixing regularly, so at least it's caught on with me

Best,

Doremus

 

[john_s]

This "stable Silver" (e.g. Ag2S) then ends in the facility's sludge. And this may end on farmland, where the Silver may be dissolved again in the soil.

I hadn't thought of that. I don't know where our sludge ends up these days: it used to go onto certain specified farmland, but maybe not these days...

 

[bluechromis]

Boy, we really need a "Fixer Best Practices" sticky thread where authoritative information on fixer shelf-life, capacities and proper disposal are available.

As for disposal of used fixer, the best I have found is to locate a working film photo lab and see if they will take your used fixer for silver recovery and subsequent disposal. Most are happy to do this if you let them keep the reclaimed silver. That's a small price to pay for doing things right. If that's not available, check with your local authorities. Often, small amounts of silver-laden fixer from non-commercial home processing are okay to dump into the sewer system. The silver then gets converted to stable silver-sulfide compounds at the treatment plant. Home silver recovery is possible, but not practical for a lot of us. Taking used fixer to a HazMat facility is my last choice; they won't recover silver and will spend a lot of energy incinerating your used fix.

As for capacities: First, read the manufacturer's instructions (Ilford has particularly good tech sheets on their fixers), or the capacity info from the formulators (there's a lot of info from Kodak and others about both conventional and rapid fixers out there). There are often different capacities given for "general" or "commercial" standards than for "archival" or "optimum permanence." If your goal is to make and sell prints made on fiber-base paper, processing for optimum permanence is really best practice. This means that fixer capacity is rather low, about 10 8x10-inch prints per liter of fix with a one-bath regime. A two-bath regime will double this and is more economical, but needs more space and an extra step. Using a wash-aid is indispensable for optimum-permanence processing of fiber-base prints

For film, the clearing test works well and is reliable. Test a piece of film with fresh fixer for clearing time. Best is to put a drop of fixer on the film, wait 30 seconds and then immerse the whole test strip in the fixer while watching carefully. Note the time when the time it takes for the area surrounding the drop to match the drop-area in transparency. This is the base-line clearing time for that film/fixer/dilution combination. Fixing time for film is then minimum twice the clearing time (I like longer). When the clearing time reaches twice that in fresh fixer, the fixer should be discarded. Note that if your save your fix and are determining your fixing time with a clearing-time test that you need to do a new clearing-time test before subsequent batches of film since the clearing time will be longer in used fixer. To avoid doing this, I like to fix my film for four times the clearing time in fresh fixer. This ensures that I have at least twice the clearing time in fixer that is just about exhausted.

Be aware that fixers for film should not be used for fixing prints. Also, be aware that fixers for film and RC papers can be used longer that fixers for fiber-base papers. Both film and RC papers will tolerate a much higher level of dissolves silver compounds in the fixer than fiber-base papers can. Fiber-base papers need fairly fresh fixer to do the job; for optimum permanence, very little dissolved silver can be in the (last) fix. A two-bath regime or frequent mixing of new fix with a one-bath regime is necessary.

Keep in mind that the "Hypo Check" / FT-1 potassium iodide check is not really that sensitive and maybe not ideal for optimum-permanence processing of fiber-base prints (unless you use it just for bath 1 of a two-bath fixing regime). Better is to test your own particular workflow for throughput using the sulfide ST-1 or the selenium toner tests for residual silver (along with the HT-2 test for adequate washing). Once you've determined the limits of your regime and added a nice safety buffer, you can then just test "last print though" to keep an eye on the process.

Since adequate fixation is dependent on the amount of dissolved silver in the fixer, the capacity for any given material and level of fixation is not affected by fixer dilution. Fixer dilution will affect the speed of fixation; the build-up of silver compounds in the fixer determines when the fixer will no longer fix adequately and needs to be discarded.

Fixers will go bad due to oxidation and sulfuring-out. Acidic rapid fixers are prone to this. "Plain-hypo" fixers also have a rather short working life and should not be stored for long periods.

There's a ton of info on this site, the LF fora and from manufacturers like Ilford, Kodak, et al., not to mention lots of books and websites on photo processing out there. There's really no excuse for not knowing how to best use your fixer of choice, how long to store it, what the capacities are, etc.

Best,

Doremus

Good information Doremus. I second the use of two-bath regime for film. It has a number of benefits in addition to prolonging the life of the fixer. It is an insurance policy if someone screws up, like I sometimes do, and allows the solution A to become exhausted because the fresher solution B will still provide some fixation. Exposing films to fresh fixer is nice thing to do to them. The authors of the "Way Beyond Monochrome" recommend using fresh fixer each time. I have heard it said that as fixer is used, but before it would be thought to be totally exhausted, it gets harder for the fixer to wring out the last bits of unexposed silver. Because the first bath does the heavy lifting of fixation, the second bath is left in better shape and can approximate fresh fixer without having to use new fixer every time. I found that once two baths became part of my regular routine, I barely notice any extra effort to use two solutions. So it may be easier to do than people expect.