Fixer, Fundamental Question

[dazedgonebye]

Ok,
How do I know when my fixer is exhausted? For the first couple of rolls, I just used it and dumped, but fixer looks to be the most expensive part of the process so I've started re-using.
Is there some indicator I can add to it?

 

[like2fiddle]

You can dip a piece of exposed film into the fixer and measure the amount of time it takes to clear the film. I usually fix for twice that time. When fixing time gets to be higher than you like, I typically don't like to fix for more than two or two and a half minutes, some say three minutes, you toss the fixer.

 

[ibcrewin]

Hypo check! It's about 7 bucks at B&H. two drops in. If you see a precipitate then it's exhausted.

I was doing the same thing. This is just nice insurance!

 

[rxmd]

Tetenal is selling test sticks for fixing bath that give an indication of the silver content.

You can also economize by using two-bath fixing. Use two bottles of fixer, a "spent" bottle and a "fresh" bottle. Fix every film two times, first using fixer from the "spent" bottle, then from the "fresh" bottle. After a number of films, pour away the "spent" bottle for recycling, pour the content of the "fresh" bottle into the "spent" bottle, and mix some new "fresh" fixer.

Because of how the chemistry of fixing works, you actually get more films fixed with a given quantity of fixer that way, because the spent fixer will still do a good job at part of the fixing process, namely removing silver from the emulsion. You can use testing sticks every ten to fifteen rolls of film or so; as long as the silver content of the "fresh" fixer stays under 1 mg/l, you can still go on fixing happily.

Philipp

 

[Roger Hicks]

A refinement of the other Roger's method:

WITH FRESH FIXER, put a drop on the film leader/scrap film.

After 15-25 seconds, put the whole leader in the fix. When you can't see the spot any more, that's your clearing time.

Fix for 2-3x the clearing time.

When the clearing time with used fixer is double the original time, mix new fixer. This incorporates a good safety margin: 3x is OK, but tedious.

This has the further advantage that you always fix for the minimum possible time.

Cheers,

R.

 

[oftheherd]

Kodak powdered fixer gives instructions on how many rolls or how many sheets of prints as I recall. One presumes it is in the best interests to be accurate. Of course, they will err on the side of caution, so testing is good.

 

[ZorkiKat]

A litre of fixer will fix about 25-30 rolls of 35mmX36 or 120, 25-30 sheets of 8X10, or about 90-100 sheets 4x5. That's what their published capacities give. That of course depends on the type of film that goes in the fixer. Some emulsions (like many of the Tgrains) will exhaust the fixer faster and give lower yields. Others like the thinner emulsion films such as EFKE 25 may exhaust the fixer more slowly.

One hypo-tester I use is plain Tincture of Iodine solution. A drop or two in a jigger full (or film-cannister full) containing the fixer solution in question will tell a lot. Good fixer will remain clear when the iodine tincture hits it. One which is halfway through will go a bit cloudy but will clear when the fixer is shaken. A really tired fixer solution will just go cloudy and won't clear.

 

[Keith]

I just go by Ilford's recommendations of the fixer's capacity numerically and keep track of the usage and discard when I've reached that figure. There's a piece of tape on the fixer bottle that I mark each time I use it with a sharpie!

 

[mr_phillip]

I just go by Ilford's recommendations of the fixer's capacity numerically and keep track of the usage and discard when I've reached that figure. There's a piece of tape on the fixer bottle that I mark each time I use it with a sharpie!

I do the self same thing, but try to stay 10% under the recommended number.

 

[drewbarb]

Roger's method for testing fix exhaustion level works perfectly, and is pretty easy. Whenever I process 35mm film, I keep the leaders I clip off and use these to test my fix. I have a box full of them in my darkroom. I track the amount of film run through my fix- I put a piece of white paper tape on the bottle with the mix date and track the amount of rolls or sheets run with a sharpie. When it gets close the number that should be the fixer's capacity, I test, and always recycle my fix before it reaches exhaustion. I keep hypo check to test print fixer, but find it unreliable for film fix.

BTW- you know you shouldn't dump fix down the drain, right? Even small quantities of used fix have enough silver to be toxic. Put a piece of steel wool into exhausted fix and let it sit for three or four days; the silver will collect on the steel wool and in the bottom of the container. You can carefully pour off the solution, leaving the metal in the container. This will effectively get most of the silver out, and you can more safely dump this, if you don't do huge amounts.

 

[dazedgonebye]

Looks like lots of good methods.
I guess I should be meticulous enough to track what I'm doing and just change after x number of films...but that's not likely to happen.
I'll try to go with one of the indicator solutions.

 

[fidget]

An even less scientific method for me. For paper, when the indicator stop bath turns colour from yellow to purple I change the stop and fix. For film I use the two fix method, first 5 mins in the old fixer, then 5 in the newer fixer. When times get to be noticeably over these then the old fixer is dumped and the newer fixer becomes the old whilst a fresh mix becomes the newer...... er.. that makes sense doesn't it?

 

[sem]

question

question

Hi,
it was pretty interesting to read all of the post. Thanks.
Does anybody know the difference between an alkali and a basic fixer. Just want to use it for barytpaper and don´t know which to use.
regards sem

 

[like2fiddle]

BTW- you know you shouldn't dump fix down the drain, right? Even small quantities of used fix have enough silver to be toxic. Put a piece of steel wool into exhausted fix and let it sit for three or four days; the silver will collect on the steel wool and in the bottom of the container. You can carefully pour off the solution, leaving the metal in the container. This will effectively get most of the silver out, and you can more safely dump this, if you don't do huge amounts.

Drew,
Thank you for pointing this out. I will try this steel wool method.

Sem, I'm not absolutely positive, but I believe basic and alkali fixer mean the same thing. (at least they are in my field of work)

 

[sem]

the is a shop (http://www.lumiere-shop.de/index.php?cat=c168_S-W-Chemie.html), where you can buy both.
Might someone know, what is better to baryt.
sem

 

[Bruin]

You can also economize by using two-bath fixing. Use two bottles of fixer, a "spent" bottle and a "fresh" bottle. Fix every film two times, first using fixer from the "spent" bottle, then from the "fresh" bottle. After a number of films, pour away the "spent" bottle for recycling, pour the content of the "fresh" bottle into the "spent" bottle, and mix some new "fresh" fixer.

Because of how the chemistry of fixing works, you actually get more films fixed with a given quantity of fixer that way, because the spent fixer will still do a good job at part of the fixing process, namely removing silver from the emulsion. You can use testing sticks every ten to fifteen rolls of film or so; as long as the silver content of the "fresh" fixer stays under 1 mg/l, you can still go on fixing happily.

Philipp

I agree with Philipp; in particular Ilford's two-bath method is the best I've found. Once you've established how many times you can use a particular batch for each bath, you don't have to watch the silver content anymore. You can be sure that your getting the most out of your fixer and that your films are properly fixed every time.

I use Freestyle's Arista Premium Odorless Liquid Fixer (same as Clayton's Odorless Liquid Fixer) and for my 16 oz. Jobo tank at the standard 1:9 dilution, I get three uses per bath. That means a freshly mixed batch gets used three times as the second bath, then it becomes the first bath for three more uses. The second bath is always the fresher one. Fix for the clearing time for each bath (for a total of double the clearing time after both baths).

 

[Roger Hicks]

BTW- you know you shouldn't dump fix down the drain, right? Even small quantities of used fix have enough silver to be toxic.

Distinctly disputable. Toxic to what, and at what stage in the water purification process?

Silver is not especially toxic stuff -- check http://www.atsdr.cdc.gov/tfacts146.html

and by the time it has been diluted in a normal sewage system it is not actually measurable by the time it reaches the sewage treatment plant.

Cheers,

R.

 

[drewbarb]

Distinctly disputable. Toxic to what, and at what stage in the water purification process?

Silver is not especially toxic stuff -- check http://www.atsdr.cdc.gov/tfacts146.html

and by the time it has been diluted in a normal sewage system it is not actually measurable by the time it reaches the sewage treatment plant.

Cheers,

R.

Once again, Roger, you come through with great information- thanks for posting this. I am extremely cautious with regard to disposal of my chemistry, for a variety of reasons. Part of my approach is due to an effort to be as environmentally non-destructive as I can be- while still running a darkroom; part is due to the laws and regulations in this country about what you can and can't dump into the sewers, (weird, arcane, different everywhere, and difficult to enforce) and finally, because I generate a greater quantity than most home darkrooms (though not as much as real commercial labs), I try to be overly careful. Still, it's nice to know I'm creating less of a problem than some might lead me to believe.

 

[Roger Hicks]

Once again, Roger, you come through with great information- thanks for posting this. I am extremely cautious with regard to disposal of my chemistry, for a variety of reasons. Part of my approach is due to an effort to be as environmentally non-destructive as I can be- while still running a darkroom; part is due to the laws and regulations in this country about what you can and can't dump into the sewers, (weird, arcane, different everywhere, and difficult to enforce) and finally, because I generate a greater quantity than most home darkrooms (though not as much as real commercial labs), I try to be overly careful. Still, it's nice to know I'm creating less of a problem than some might lead me to believe.

Dear Drew,

You are more than welcome. I fully support your stance on environmental issues, and a precautionary principle in disposing of waste, and I share your bewilderment about local regulations on what can and can't be tipped into a sewer; but if more people read the CDC's site, local regulations might be a bit less hysterical...

By way of an experiment sometime, dilute used fixer 1+20 or more and use it in a watering can on your lawn. It comes up beautifully -- much better for it than dog pee!

Cheers,

R.

 

[Tom A]

I keep track of how many films goes through my Kodafix and I dump it after 60 rolls or 6 weeks -whichever comes first.
The steel wool system works for collecting silver, but beware of the smell and keep the canister outdoors!!!
Only caveat to dumping fixer down the drain is if you are on a septic tank system. Then even relatively small volumes can affect it. In a city water system it is not as critcal as you dilute it with all the other stuff that goes out.
I like Rogers idea of watering the lawn with diluted fixer! Should keep the moles from it too. Sooner or later you will have nice shiny silvery colored blades of grass too, I assume. Instead of cutting the lawn you polish the individual blades of grass!