Question on 4X5 and Fixer Exhaustion

Most 35mm and 120 roll film standards for Fixer use seem to run north of 12 but less than 18 rolls. I didn't see much in the instructions for gauging the potential in fixing 4X5. In this case, I'm running it in a Jobo tank with 6 sheets and roughly 1250 or so ML in fluid to cover it using traditional inversion (not rotary). So far so good. Sure there's a way to do the math for the comparable sheets to a roll of film, but maybe someone knows a shorthand rule of thumb?

4 sheets of 5x4 are equivalent to one roll of 35mm or 120, think of a contact sheet it's 10x8

Ian

JWMster said:

Most 35mm and 120 roll film standards for Fixer use seem to run north of 12 but less than 18 rolls. I didn't see much in the instructions for gauging the potential in fixing 4X5. In this case, I'm running it in a Jobo tank with 6 sheets and roughly 1250 or so ML in fluid to cover it using traditional inversion (not rotary). So far so good. Sure there's a way to do the math for the comparable sheets to a roll of film, but maybe someone knows a shorthand rule of thumb?

Click to expand...

If my rapidly declining memory still "works" well enough
...when you get to 'twice' the clearing time of 'fresh' mixed fixer its time to mix a new 'batch'
(but... I may be 'wrong' (again... dammit!!!!!)

Ken

KenS said:

...when you get to 'twice' the clearing time of 'fresh' mixed fixer its time to mix a new 'batch'

Click to expand...

Same here. We must be on the same side of Alzheimer.

On top of a count based estimation, have you considered two-stage fixing?

Initial fixing bath is your old-but-not-yet-exhausted fix, which is then used up more aggressively than your second bath fix. When that is spent, whether calculated or tested, you switch your previous second bath to the first, and mix fresh chemistry for your second bath.

Twice the clearing time is good advice.

Luckless said:

On top of a count based estimation, have you considered two-stage fixing?

Initial fixing bath is your old-but-not-yet-exhausted fix, which is then used up more aggressively than your second bath fix. When that is spent, whether calculated or tested, you switch your previous second bath to the first, and mix fresh chemistry for your second bath.

Click to expand...

That's what I do when I've gone way beyond twice the fixing time.

Two stage fixing will obviously work, but I don't see the point for film. Fixer is rather cheap.

Thought about 2 stage fixing. Haven't gone there yet. My standard STOP approach used to be RINSE - STOP - RINSE just to keep the FIXER as uncontaminated as possible. One of the old JOBO newsketter's suggested this as part of the author's routine and it seemed like a decent idea, so I tried it, and FIXER lasts longer this way. But since switching to Caffenol where the standard STOP is simply water, I do a RINSE X 2 and on to FIX. Kind of the same idea. So far, haven't been tempted, and like koraks above, I just mix up a fresh batch. Hardest thing about FIXER is disposal (local Hazmat Dump keeps odd hours).... and no, haven't tried recylcing the silver.

Oh... and I'll bet my mind will either wander or "blue screen" (aka BSD) as fast as anyone else's.

Thanks for the help, guys!

Two-Bath Fixing

Used correctly, 2-bath fixing gives the same fixing capacity but guarantees complete fixing, which might fail if you over-use the fixer somewhat. Such an error won’t hurt the final result in 2-bath fixing, as Fix 2 finishes the job. Most fixers have a capacity of 25 rolls = 25 8” x 10” sheets = 100 4” x 5” sheets = 2000 square inches with standard films. For example, that’s the stated capacity of Kodak Professional Fixer. In my experience, two-bath fixing does a superior job of removing the magenta-colored dyes from Kodak B&W films compared to using a single bath, especially as the fixer accumulates use.

This is reduced to 2/3 or about 17 rolls = 67 4” x 5” sheets = 1333 square inches for Kodak T-Max films. Always check the fixer-maker’s data to be sure of its fixing capacity.

In use, you’d mix 2 liters of fresh fixer and store each in bottles labeled “Film Fix 1” and Film Fix 2”. Fix the film for one-half of the recommended fixing time in Fix 1. Then finish the fixing in Fix 2, returning each bath to its labeled bottle and recording the usage.

When you reach the stated capacity for one liter, discard the heavily-worked Fix 1, pour the contents of the lightly-worked Fix 2 bottle into the Fix 1 bottle (old Fix 2 is demoted to the new Fix 1), and mix a fresh liter of Fix 2. Repeat each time you reach the stated capacity for one liter of fixer. In this way, you get complete fixing and all of the fixing capacity for which you paid.

Although written for fixing paper, the same principle applies to film fixing as it does to fixing papers in the following excerpt from page 86 of

Amphoto Home Darkroom Course
Advanced Black and White
John S. Carrol
Copyright © 1977 by American Photographic Book Publishing Company

“Two-Bath Fixing

The thin, fine-grained emulsion of a print paper is fixed very rapidly; in a fresh hypo bath it takes no more than a minute or two for completed fixing. However, in a fixing bath that is approaching exhaustion, fixing will not be complete in any length of time.

The way it works is this: in dissolving out the unexposed silver halides, the fixing bath first converts them to complex silver-sodium-thiosulfate compounds. These are not soluble in water, but will dissolve in fresh hypo; in practice, their removal takes place at the same time as their formation in fresh fixing bath. However, when a certain concentration of these complexes exists in the fixing bath, the bath becomes saturated with them and will not dissolve any more of them from the paper emulsion. If the print is washed at this stage it will still contain large quantities of silver and thiosulfate salts, which are not soluble in water and are not removed by the washing. It is this retained silver salt which is responsible for eventual staining of prints kept for a long time.

However, if the print is not allowed to stay in the partly exhausted hypo bath for too long, the silver-sodium-thiosulfate complex is still soluble in fresh hypo; this is the basis of the two-bath system of fixing.

For this method, you need four trays—developer, stop bath, first fixing bath and second fixing bath (both trays contain F5 or similar fixers). The first bath removes most of the silver halides; the second bath will accumulate little silver and can easily dispose of what is left in the paper plus the difficult-to-dissolve complexes. The two baths are good for as many as two hundred 8” x 10” prints for a gallon of each; when that many prints have been fixed, discard the first bath, transfer the second bath to the first tray, and mix a new second bath. The combination is again good for 200 prints.”

Ian et al: Thanks! Helpful and convincing. Yes, I've been thinking about it. May head there.... e-v-e-n-t-u-a-l-l-y. Maybe next time I make up FIXER and get a bottle from our Formulary Friends in Montana.

koraks said:

Two stage fixing will obviously work, but I don't see the point for film. Fixer is rather cheap.

Click to expand...

True, but getting more safe use out of the same volume of fixer is cheaper... [Unless you account time costs. But if you value your time high enough then any question about chemistry cost is out the window as paying someone else to deal with it is obviously cheaper.]

First, Ian Grant has your answer: four 4x5 sheets = 1 36 exp. roll of 35mm film = 1 8x10 sheet. You can do the numbers yourself.

Ian C has also given good advice. I use two-bath fixation for films as well as prints these days. It's not hard or time consuming. One addition to Ian's comments: As you cycle through the fixer, replacing bath one when exhausted with bath two, you should only do this 5-7 cycles before mixing both baths fresh. And, do keep an eye on the age of the fixer too.

If you want to just use single bath fixation for film, then keep an eye on the throughput and don't exceed the capacity of the fixer (more later). Err on the side of running less film through the fix than vice-versa.

A quick note on fixer capacities for film: The capacity really depends on the type of film you are using, as does fixing time. Newer tabular-grain films exhaust the fixer faster than conventional films and take longer to fix. The former include Kodak T-Max and Ilford Delta films. It's good to read the film data sheet for fixer capacity as well. You'll notice that some fixer manufacturers don't give separate capacities or times for tabular-grain and conventional films; just one capacity number range and time range that applies to the all kinds of film. Ilford is frustratingly vague on these points.

The best way to find both capacity and fixing time for your particular film is to do the clip test (Ilford describes that in gratifying detail in their fixer data sheets at least). You should establish a clearing time for a given film in fresh fixer. The fixer should be discarded at or before the point that the clearing time in the used fixer reaches twice that in fresh fix. To determine fixing time, you need to do a clip test before each batch. Fix for at least twice that clearing time (not the clearing time for fresh fix!). Note that this time changes as the fixer exhausts, so you really need to do the clip test every time if you want to keep fixing time to a minimum. My preferred approach, however, is to find the clearing time in fresh fixer, double that (to the clearing time in fixer ready to discard) and then double that again (for the fixing time in fixer ready to discard). This is 4x the clearing time in fresh fix, which I use as a minimum fixing time from the get-go, even in fresh fix. The extra time does no damage to film, helps clear the pink dyes a bit more and keeps me from having to clip test every time. Then, just clip test toward the end of your fixer life to find when to toss it.

If you use two-bath fixing, then you only need to clip test fix 1.

Best,

Doremus

Doremus Scudder said:

Ian C has also given good advice. I use two-bath fixation for films as well as prints these days. It's not hard or time consuming. One addition to Ian's comments: As you cycle through the fixer, replacing bath one when exhausted with bath two, you should only do this 5-7 cycles before mixing both baths fresh. And, do keep an eye on the age of the fixer too.

Click to expand...

Any reason to drop a batch of reuse-fixer 'early' and mix both from scratch again? Isn't the point of the first bath to ensure greater and more reliable usage of all of your fixer by depleting the active chemistry of the older fixer with a first-stage bath so that less chemistry usage is needed when it hits the fresher second stage bath?

80 square inches of film any size is one "roll".

• One 8x10
• Two 5x7
• Four 4x5
• 0.5 220
• One 120
• One 35mm 36 exp.

Luckless said:

Any reason to drop a batch of reuse-fixer 'early' and mix both from scratch again? Isn't the point of the first bath to ensure greater and more reliable usage of all of your fixer by depleting the active chemistry of the older fixer with a first-stage bath so that less chemistry usage is needed when it hits the fresher second stage bath?

Click to expand...

First, remember that with two-bath fixing, it is bath one that is the older, more exhausted bath. Bath two is the fresh, newer, more active one.

When using two-bath fixing, the second bath doesn't do the lion's share of the fixing; that happens in bath one. However, it does do some, especially as bath one is approaching the end of its useful life. So a buildup of dissolved silver does occur. Plus, there is a certain amount of dissolved silver that gets carried over from fix one. When fix two gets moved to the fix one position, then, it's not 100% fresh. Over a few cycles of this, fix one is doing less and less of the total work (it is progressively more exhausted), and bath two accrues more and more dissolved silver. At some point, the second bath has too much silver in it to effectively function as bath one anymore, at which point we need to replace it as well. Kodak recommends no more than seven cycles of replacing bath one with bath two. I like five cycles or fewer, out of an abundance of caution.

A quick note on fixer capacity and permanence: Although manufacturers state that xx prints can be run through a liter of fixer, the number we usually see is for "general purpose" or "commercial use," not for "optimum permanence" or "archival processing."

If you read the Ilford data sheet on their fixers, the capacity is given as 40 8x10 prints per liter. But, if you read more carefully in the section on silver concentration, you'll find that that capacity is for "commercial use." For "maximum stability" or "optimum permanence" the capacity is only Ten 8x10s per liter. With one bath fixing, then, you'd be discarding bath one every ten prints if you're interested in optimum permanence.

With two-bath fixation, you can run 40 8x10s through a liter of bath one, then transfer to bath two and get the same or better fixation as the 10th sheet through a one-bath-fixation regime. You've doubled your fixer capacity even if you discard both baths. If you promote bath two to bath one, your saving even more. The two-bath-fixing regime is more about ensuring adequate fixing for optimum permanence than for economy. Still, it's more economical too.

Additionally, we need to keep an eye on the age of the fixer; fixer needs to be replaced at the end of its shelf-life regardless of the throughput. Fixer in an open tray lasts about 7 days; in a half-full bottle about a month; six months in a full, tightly-capped bottle.

Best,

Doremus

I do 2-bath fixing for film, and I'm pretty conservative about fixer life. I also use HCA on every sheet or roll, and I've tested my wash times with RHT. But every shot I take is usually from travel/planning, or it was a huge hassle to get, or it's models/makeup/props - thus I don't shoot much, but what I do shoot, I really like, and the negs get printed. The film feels irreplaceable and precious... so being meticulous is a good value for me. If I were blowing through rolls of 35 on the street every week, I might lighten up a little!

Doremus Scudder said:

When using two-bath fixing, the second bath doesn't do the lion's share of the fixing; that happens in bath one. However, it does do some, especially as bath one is approaching the end of its useful life. So a buildup of dissolved silver does occur. Plus, there is a certain amount of dissolved silver that gets carried over from fix one. When fix two gets moved to the fix one position, then, it's not 100% fresh. Over a few cycles of this, fix one is doing less and less of the total work (it is progressively more exhausted), and bath two accrues more and more dissolved silver.

Click to expand...

While this is true if you gauge your fixer life by number of rolls/sheets/prints processed, if you base the Fix 1 life on a clearing time test, you'll never exhaust Fix 1 enough that Fix 2 winds up doing the lion's share of the fixing. Yes, it adds a little work -- if you're all about saving effort, use a more dilute fixer and mix it fresh for each print session/developing run, then just discard it when you close up for the day.

Donald,
Good to see you posting!

Thanks, Matt. I'm actively working on getting back into the darkroom. Just bought an RB67, some fresh .EDU Ultra 100 and 400, and a powder mix for CineStill DF96 monobath (supposed to be good for 16 rolls). Still got all my equipment, but haven't been able to use it for close to twelve years. With a little luck, I'll be able to set up my enlarger by the end of this year.

Donald Qualls said:

Thanks, Matt. I'm actively working on getting back into the darkroom. Just bought an RB67, some fresh .EDU Ultra 100 and 400, and a powder mix for CineStill DF96 monobath (supposed to be good for 16 rolls). Still got all my equipment, but haven't been able to use it for close to twelve years. With a little luck, I'll be able to set up my enlarger by the end of this year.

Click to expand...

Best news I've heard in a long time!

Donald Qualls said:

While this is true if you gauge your fixer life by number of rolls/sheets/prints processed, if you base the Fix 1 life on a clearing time test, you'll never exhaust Fix 1 enough that Fix 2 winds up doing the lion's share of the fixing. Yes, it adds a little work -- if you're all about saving effort, use a more dilute fixer and mix it fresh for each print session/developing run, then just discard it when you close up for the day.

Click to expand...

Donald,

Nice to see you back as well.

I don't know what clearing test you are using for print fixer, but in my experience, using a film-clearing test to test fix for fiber-base prints is not nearly sensitive enough to accurately let me know when fix 1 has reached 2g/liter of dissolved silver. It works pretty well for film fixer: a doubling in time lets you know that the film fix has reached 8-10g/liter of dissolved silver. I've seen test strips for sale that were sensitive enough, just rather expensive... I imagine one could get some strips and calibrate a film-clearing test so one knew what time increase for film clearing equaled that 2g/liter threshold, but I haven't done that. Using a doubling in time is definitely not going to work for fix 1 for an optimum-permanence sequence.

In any case, as one cycles through the fix 2 to fix 1 promotion a few times, fix 1 becomes progressively more laden with dissolved silver. Even if one had a reliable clearing or strip test, the capacity of fix 1 would gradually be reduced to the point where mixing new would be prudent.

FWIW, I use Ilford Rapid Fixer or Hypam (or another similar rapid fixer) at the "print" dilution, i.e, 1+9 for the Ilford products. I'm not trying to squeeze as much economy out of my fixer as I can. I always mix new fix for fix 2, which sometimes doesn't get promoted to fix 1. I rarely make even the five-to-seven cycles Kodak says are possible.

Using fix 1+9 lengthens my fixing times (1.5-2 minutes in each bath) and extends my wash time, but I really find it inconvenient to use the Ilford sequence that involves "film-strength" fixer and short times. 30 seconds in each bath with large prints is almost impossible to achieve. Heck, it takes 15 seconds or more for a 16x20 print to drain. Do I include this drain time in the total fixing time? If not, does the paper base become more saturated when I have a long drain time, thus increasing time needed for washing. And, what if I'm bleaching and need to return a print to the fixer after bleaching a time or two; how does that affect wash time? I prefer to use the tried-and-true Kodak recommendations: full fixing, rinse, wash aid, and a long wash.

Best,

Doremus

koraks said:

Two stage fixing will obviously work, but I don't see the point for film. Fixer is rather cheap.

Click to expand...

Two stage fixing works really well with the Tmax films I've never seen the need with other black and white films.

One more thought, then I'm done with thinking for the day. When you fix film you convert silver halides into silver thiosulfites. But it's not just one argentothiosulfite it's at least four different argentothiosulfites (I love that word, read it an old English text). Some are more soluble than others. If you use fixer that is older with lots of argentothiosulfite already in it (or If you fix with less agitation and you build a very thin layer of exhausted fixer right next to the film) this forces the fixation by products more towards the less soluble argentothiosulfites and your film is much harder to properly wash. You film still clears but you never can get all the fixation by products to wash out. Steiglietz thought Kodak was trying to sell more fixer and that was why they recommended only a few films per pound of sodium thiosulfite (hyposulfate of soda). His negatives paid the price for his frugality.

I have to apologize for confusing the issue here and clarify a bit. I've mixed up the thread by talking about fixing prints as well as film. I really need to address these separately.

First, Donald; Yes a clip-test is fine for the first fixing bath of film fixer; that's what I do. It doesn't work for archival processing of fiber-base prints, however, because print fixer has to have a lot less dissolved silver in it to work and a film-clearing test isn't sensitive enough to tell you when to discard the fix. The 2x clearing time rule is only good for film, not for fiber-base prints. Throughput coupled with two-bath fixation seems the best way to ensure adequate fixation of prints. You likely already know all this; sorry if my answer was confusing.

Best,

Doremus

Doremus Scudder said:

Yes a clip-test is fine for the first fixing bath of film fixer; that's what I do. It doesn't work for archival processing of fiber-base prints, however, because print fixer has to have a lot less dissolved silver in it to work and a film-clearing test isn't sensitive enough to tell you when to discard the fix. The 2x clearing time rule is only good for film, not for fiber-base prints. Throughput coupled with two-bath fixation seems the best way to ensure adequate fixation of prints. You likely already know all this; sorry if my answer was confusing.

Click to expand...

Actually, I wasn't aware there was that much difference between fixing film and fixing prints. I've got a lot more experience with film than with prints, and most of my printing has been on RC paper and seen as practice in printing, rather than expected to last fifty years on someone's wall (or five hundred in a museum vault).

Generally, i my own darkroom I've mixed my own fix, Ansel's plain hypo or with a varied amount of sulfite depending what I was doing. I've one-shotted it. That last will probably change, my new setup is on a septic and I can't put silver down there without risking killing the tank -- which would reduce my popularity. I might have to dig a dry well to dispose of my fixer in a dog- and cat-safe manner. Either that, or start using it to exhaustion and recover the silver.