Extending Fix Times

dancqu · Nov 12, 2008

It occurred to that as more and more films are put through
some developers the development times are increased. Is it
a common practice to do the same amoung those that slowly
exhaust a fixer with ever more through put? Dan

Claire Senft · Nov 12, 2008

Just the normal 2x the clearing time. When the original time has doubled then I make more from fixer scratch. I have been using quite a bit of Imagelink HQ. In regular, not rapid fixer, it clears within seconds. I develop my film in the dark with 4 tanks that each have their own chemical and the reels on a lifting rod. I have yet to pull the film from the fixer without it being completely cleared.

dancqu · Nov 12, 2008

Claire Senft said:
Just the normal 2x the clearing time. When the original
time has doubled then I make more from fixer scratch.

I goofed my first post. I had in mind prints and I suppose
FB at that. I'm reminded of Ilford's archival sequence of
some years ago. One minute in film strength fixer,
from first through forty. Dan

Photo Engineer · Nov 12, 2008

There is a simple test for determining fix time visually for paper. I'll leave it to the student to figure it out.

PE

Doremus Scudder · Nov 14, 2008

OK PE, I'll bite...

Here's what I do to determine clearing time for papers.

Under safelight, I immerse a test strip of paper in the fixer in stages. The strip is marked in "inches" with a Sharpie. 20-second intervals are close enough for me. The first "inch" gets 20 seconds, then the second "inch" is immersed and so on. After I've done this to a total of a few minutes, I rinse, turn on the white light and toss the strip into the print developer.

The strip that is completely paper-base white with the least fixing time is the clearing time for the paper.

Easier done than said...

And, while I'm at it dancqu... I used to determine clearing time for each batch of negatives with a clearing test and adjust fixing time accordingly (i.e. three times the clearing time). Now, however, I use two-bath fixing for negatives and prints, and though I still use clip tests to determine exhaustion of the first bath, I no longer extend fixing time. That is one of the advantages of the two-bath method.

I do use dilute fix one-shot every now and then for the occasions when I only have a very few negatives to develop at one time, but mostly develop now in larger batches (40+ sheets), which lends itself better to the two-bath method.

Best,

Doremus Scudder

www.DoremusScudder.com

titrisol · Nov 14, 2008

IMHO only the Tmaxes require longer fix time.
I normally test the clearing time of film every ~6-7 rolls and then dump the fixer or adjust the time.

Photo Engineer · Nov 14, 2008

There are 3 tests Doremus, and you nailed just about the hardest.

The other two can be done without any washing needed, and one sacrifices about 1 ml of fix.

I thought Dan, being an expert, would have all 3 by now.

PE

kodachrome64 · Nov 14, 2008

Photo Engineer said:
There are 3 tests Doremus, and you nailed just about the hardest.

The other two can be done without any washing needed, and one sacrifices about 1 ml of fix.

I thought Dan, being an expert, would have all 3 by now.

PE

Well, can someone indulge those of us who aren't "experts"?

wogster · Nov 14, 2008

dancqu said:
It occurred to that as more and more films are put through
some developers the development times are increased. Is it
a common practice to do the same amoung those that slowly
exhaust a fixer with ever more through put? Dan

I don't think, when I had my darkroom, I ever totally exhausted fixer, I always did film as one shot, for both develop and fix, because it left me with the most consistent results. Figured the slightly higher process cost was cheaper then ruining negatives, and having to try and repeat a shoot.

For paper I would mix up a batch, and when the session was over, I would toss it, even printing all day, I don't think I ever exhausted fixer. You should probably read the directions for the fixer, as it should tell you the capacity. The spec sheet for Ilford Rapid fixer has capacities on it, you can get the spec sheet from the Ilford website. Kodak probably has the same info on their website for their fixers.

Then again I have to admit, I had a pretty low volume operation....

Our high school darkroom did it this way, there was a label on the shelf by the developer bottle, every time you did a roll, you marked it on the label. Every 10 rolls you tossed the developer, stop and fix and mixed up fresh. The capacity of the fixer and stop were more then the developer, this worked well for a lab that might see 40 rolls on a single day..... Beside the label was a chart of time based on the number of rolls..... I often did my processing at home though, because there was usually a lineup at school. IIRC they had a machine for print processing (it was 28 years ago now), so unless it was a weekend and I wanted my results for Monday, I printed at school.

dancqu · Nov 15, 2008

Photo Engineer said:
I thought Dan, being an expert, would have all 3 by now. PE

I don't test for the amount of time needed to clear. I test for
the amount of chemistry needed to clear within some fixed
time; currently 4 minutes. Recall I use fixer one-shot.

Test are done with 5x7 sheets, with a water presoak. More of
a real world test at least for those who water stop. The ST-1
test will produce a silver sulfide stain if fixing is inadequate;
silver left in the emulsion. I believe a full wash is needed
do to residual fixer will carry some little silver.

BTW, films and papers vary in the amount of fixer and
time required. Dan

Kirk Keyes · Nov 15, 2008

One shot fix is pretty wasteful. I use two bath fixing for both film and papers, and I test the first bath with KI solution to determine when to toss it.

Photo Engineer · Nov 15, 2008

dancqu said:
I don't test for the amount of time needed to clear. I test for
the amount of chemistry needed to clear within some fixed
time; currently 4 minutes. Recall I use fixer one-shot.

Test are done with 5x7 sheets, with a water presoak. More of
a real world test at least for those who water stop. The ST-1
test will produce a silver sulfide stain if fixing is inadequate;
silver left in the emulsion. I believe a full wash is needed
do to residual fixer will carry some little silver.

BTW, films and papers vary in the amount of fixer and
time required. Dan

Dan;

Your last paragraph is the most fundamental and telling comment of all regarding fixation and this is why I recommend testing.

However, your first part is indicative of conditions so at variance with most everyone else that it skews both your fixation and wash conditions badly from the rest of us who use "normal" dilutions. This is why I have differed with you with respect to fix and wash conditions and have suggested tests.

Using dilute fixers and long times will change most all facts and figures and therefore will not be representative.

A "normal" fix used for short times will still alter and extend wash times over a dilute but longer fix, but the dilute fix may not fix properly or wash properly. This again varies from film to film and paper to paper.

A high iodide film with a dilute fix can sometimes fail the Sodium Sulfide test due to the formation of a pure Silver Iodide ppt which is sluggish to react with the Sulfide test solution. It does react, but ever so slowly due to the pKsps involved and can give a false negative at first appearance. It is doubly difficult to see in film and is rare in paper today except in AgCl/I emulsion papers which do exist. The failure is much rarer in papers though as Iodide is usually very low.

PE

wogster · Nov 15, 2008

Kirk Keyes said:
One shot fix is pretty wasteful. I use two bath fixing for both film and papers, and I test the first bath with KI solution to determine when to toss it.

I think the dilution is 1:9 so for 250ml of working fix that takes 25ml of concentrate, means a 1L bottle of fix is good for about 40 rolls. You mix it up and keep it, it's good for about 40 rolls..... It depends on your workflow, I haven't made prints in nearly 25 years, and unless I win the lotto, I probably will not reopen the full darkroom ever again. These days I shoot and process the occasional roll, but because I also shoot digital, and most of the shooting these days is digital, there is a pretty good chance the chemistries will expire before I use them all. This past summer, the weather was so crappy (we had precipitation 5 days out of 7 from November of 2007 right through until now, only 4 weekends where at least one day was dry, and always a day I had some kind of commitment or another. Over that period I had less then 100 shots on digital and no film at all.

Photo Engineer · Nov 15, 2008

It is pretty hard to make a 1:9 fixer for film that can be reused with any degree of capacity. 1:9 is pretty dilute for any solution of hypo.

PE

wogster · Nov 15, 2008

Photo Engineer said:
It is pretty hard to make a 1:9 fixer for film that can be reused with any degree of capacity. 1:9 is pretty dilute for any solution of hypo.

PE

Which is why I use it one shot, now it is Ilford Rapid Fixer, so maybe if one was using hypo it would not work as well.....

Photo Engineer · Nov 15, 2008

At 1:9, 60% hypo would leave you with 60 grams of ammonium hypo in 1 liter. It needs more kick than that to do a decent job in a reasonable time. With extended times you are right.

PE

dancqu · Nov 15, 2008

Kirk Keyes said:
One shot fix is pretty wasteful. I use two bath fixing for
both film and papers, and I test the first bath with KI
solution to determine when to toss it.

Not wasteful, that depending upon how dilute, how much
and often used, and what form it is in.

I didn't pull very dilute fixer out of thin air. I process single
tray so the use of very dilute one-shot chemistry fits right in.
Such information as Eddie Ephraums 1/4 strength paper fix
and Mr. Gainers and others ounce of concentrate added to
a tank of developer convinced me that if they can do it I
can to. So encouraged I've taken very dilute fixer to
extremes then backed off for sure results.

I've not used rapid fix for some years now. Having little
volume and wishing for long term keeping quality I've gone
to the slow earlier standby sodium thiosulfate. Ilford states
the capacity of 1ltr Rapid concentrate at 120 rolls of135-36.
Never did use so little but with fresh concentrate found
15ml, 1/2 ounce, good for a few films. Later I upped it
to 20ml due to aging concentrate; dilution, 1:24.

Single tray processing, a big space saver. A second tray
is needed for a hold/soak. THE 4 minute fix follows a very
dilute one shot developer, NO stop. One or a few at same
time prints may be done. All in all quite similar to one-
shot tube processing but more convenient. View the
print as it develops.

I find the method a gas. Tests precede processing. No
during or post processing tests to do. Known chemistry
strengths allow consistency. No rebottling. Save space.
Developer and fix, down the drain each or a few prints.
The very dilute fix will wash out with less water. Dan

wogster · Nov 16, 2008

Photo Engineer said:
At 1:9, 60% hypo would leave you with 60 grams of ammonium hypo in 1 liter. It needs more kick than that to do a decent job in a reasonable time. With extended times you are right.

PE

Your right, this is what I get for typing without checking my notes, for films it's 1:4 so for a 250ml tank it's 50ml of concentrate, so 20 films per litre, could reuse it, I guess, but then you need to keep track of how many rolls through the fixer bath, or use replenishment, it ends up being either keeping track of a lot of bottles or doing a lot of extra math.......

Kirk Keyes · Nov 16, 2008

wogster said:
but then you need to keep track of how many rolls through the fixer bath, or use replenishment, it ends up being either keeping track of a lot of bottles or doing a lot of extra math.......

No need to do any math or keep track of anything with two bath fixing. You only need to test the first bath after every use. It takes a few seconds to add a bit of KI solution to the fix and see if it forms a precipitate. If it does, you dump the first fix bath, move/relabel the second fix bath into first bath postition, and then prepare a new second bath. Take your fix time with your fixer and divide by two and use each bath for that period of time.

Not a lot of extra math.

Dan - where are you? And when are we Oregonians going to get together and meet?

wogster · Nov 16, 2008

Kirk Keyes said:
No need to do any math or keep track of anything with two bath fixing. You only need to test the first bath after every use. It takes a few seconds to add a bit of KI solution to the fix and see if it forms a precipitate. If it does, you dump the first fix bath, move/relabel the second fix bath into first bath postition, and then prepare a new second bath. Take your fix time with your fixer and divide by two and use each bath for that period of time.

Not a lot of extra math.

No, but it would mean needing to store 3 bottles of fixer (bath one, bath two, concentrate) plus the bottle of KI solution. When the darkroom is the kitchen sink, and you have a plastic tote with all the equipment and supplies in it between uses, having to keep extra bottles is a chore I would rather not have to deal with. Plus, I don't shoot a lot of film, maybe a roll or two a month, working strength solutions don't last that long unless the bottles are right full and tightly capped. As is once the concentrate is open it needs to be used within 6 months, at maybe 20 rolls a year, it's not really that wasteful. I have a couple of 500ml bottles, I buy 1L a year and split it among the two bottles, so it's whether the concentrate is runs out, before it expires.....Do the same with developer, have a 1L accordion bottle half filled with glass beads, keep half in there and half in a 500ml full bottle, buy 1L a year.....

Photo Engineer · Nov 16, 2008

Never ever drop any KI solution into the fix. It will slowly poison it due to the potassium buildup and iodide buildup. Take a 1 ml sample of the fix and add 1 - 2 drops of the KI solution to it. If a heavy yellow ppt forms, then the fixer is bad.

Dispersal of the KI solution into a large tray can give a false negative.

PE

Kirk Keyes · Nov 16, 2008

Right - you need to dip a bit of the fixer out and test that separately. I failed to mention that earlier.

Kirk Keyes · Nov 16, 2008

wogster said:
No, but it would mean needing to store 3 bottles of fixer (bath one, bath two, concentrate) plus the bottle of KI solution.

Well, the fixer test solution bottle will only be a once or two. It can fit in between the rest. If space is your primary concern, then do what you need to do.

dancqu · Nov 16, 2008

wogster said:
... for films it's 1:4 so for a 250ml tank it's 50ml of
concentrate, so 20 films per litre,

So you calculate that at a dilution of 1:4, a liter of concentrate
has a capacity of 20 rolls. According to Ilford a liter of their rapid
fix has a capacity of 120 rolls. That's quite a difference; 100 rolls.
Doing a little arithmetic and according to Ilford, 5/6 or a full 83
percent of the fixer is wasted if used as suggested.

If used as I've several times suggested, 20ml of concentrate
in whatever solution volume needed, then 50 rolls. That 20ml
is quite a bit mone than the 8 + milliliters Ilford claims needed.
I used 15ml in a solution volume of 500ml for some time; 66
rolls. A more exact amount may be even less, depending
upon the film and how long you wish to intermittently
agitate. The more dilute the more time.

If one sticks to the same one or two films and wishes to use
fixer frugally fresh each roll then testing for the minimum
needed to thoroughly do the job is worthwhile. Dan

wogster · Nov 17, 2008

dancqu said:
So you calculate that at a dilution of 1:4, a liter of concentrate
has a capacity of 20 rolls. According to Ilford a liter of their rapid
fix has a capacity of 120 rolls. That's quite a difference; 100 rolls.
Doing a little arithmetic and according to Ilford, 5/6 or a full 83
percent of the fixer is wasted if used as suggested.

If used as I've several times suggested, 20ml of concentrate
in whatever solution volume needed, then 50 rolls. That 20ml
is quite a bit mone than the 8 + milliliters Ilford claims needed.
I used 15ml in a solution volume of 500ml for some time; 66
rolls. A more exact amount may be even less, depending
upon the film and how long you wish to intermittently
agitate. The more dilute the more time.

If one sticks to the same one or two films and wishes to use
fixer frugally fresh each roll then testing for the minimum
needed to thoroughly do the job is worthwhile. Dan

Everybody seems to be neglecting an important point, arguing against my methodology. Maybe I'll take 52 rolls worth of photos in a year, half of that is (gasp) digital, so that leaves 26 rolls, 1/4 of those are going to be colour film, for one reason or another, so maybe 19 to 20 rolls B&W in a good year. Okay so I can use complex methods, to use a lot less fixer, and then end up tossing a half bottle because it's expired..... I haven't made silver prints in almost a quarter century. I closed the darkroom in 1984, I have done a little film processing here and there in the last 3-4 years, then scan the result. If I want a nice big silver print, I'll take my negative to a lab.....

Extending Fix Times

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