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Diluting Kodak Fixer?

dhkirby

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Sep 8, 2012
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35mm
Hi All,
A friend of mine who has a lot of experience (and thus my respect) recently suggested that I try diluting Kodak Fixer, the powder stuff (not rapid fixer, KODAFIX or Polymax; just the regular powder fixer), at a 1:1 dilution and fix for 10 minutes, but not re-use it as much. As he stores a gallon in many smaller bottles, this keeps mixing the used fixer with the unused fixer and stores almost all of it in fully filled bottles, ostensibly increasing the shelf life of the solution. He usually knows his business so I figured I'd give it a try. I did and the negs appear to have come out fine, but the one thing that I can't tell from a quick little test is whether this would have effects on the archival quality of the film. Theoretically, I was thinking that it ought to work, because there ought to still be enough reactants in the solution to fix the film, but what do you think? How would doing this affect the long-term stability of the developed film?
Thanks,
Dan
 
Kodak Fixer is strictly as-is. Great stuff, but use it like it says.
 
A bit of advice -- never ask your friend for advice.
 
Well he's a friend that I've known my entire life, and he actually has more experience than I do. He's older than I am and he's always been a mentor to me -- he was the one who got me into film in the first place, so that's why I was considering his method. But yeah, I guess it's pretty solid just to follow the instructions. I'll let him do his thing, and I'll go back to the book. That'd probably be the safest. Thanks again guys.
 
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My binder full of spectacularly screwed up negatives were all sponsored by dramatically modifying the manufacturer's directions. Let's see there was the uneven development with stand developing. Then there was uneven developing because of using a water stop bath. There was inadequate development because the water was too cold. There was the air bells because I bought and mixed up my own chemistry from Photographers Formulary and didn't realize without adding in a surfactant I would be in for air bell city. The list goes on and on.

Interestingly my colleague who had no interest in fiddling with different chemistries, developing techniques, exotic films, etc has a binder full of negatives they developed perfectly in lowly D-76 in a school darkroom robotically following directions on the wall and never bothering to understand or question them.
 
There are a lot of methods that people follow that may not be "best practice", but they are the way they've always done things. The rub is that other details of the workflow that have been adapted to the non-standard practice may get left out in the retelling.

As long as it is fixed sufficiently, film doesn't suffer much from extended time in fix, but most people like to keep fiber paper in fix for the minimum possible time to limit the fix by-products that end up in the paper fibers. So by using more dilution you are theoretically making it more difficult to wash your prints adequately, even though the film would probably be just fine. Fixer lasts until it has taken up its limit in silver, so diluting it doesn't really buy you anything. But, if you want to depart from the label recommendations you should also do tests for retained silver and retained fix, only with that testing will you know what works and have the information you need to determine what the possible benefit might be.
 
Your friend's method may work and in fact, may work very well. I just don't know and there isn't any data to support one way or the other.

BUT... for what purpose would you want to modify what Kodak says? They researched and tested it in their professional lab by chemists that do this kind of thing. Mixed as instructed, a gallon of fixer processes 100 regular rolls of films. Instruction says 2 months but it actually works far longer than that, like 6 months+.

Do you need more capacity than THAT?
 
Reducing the concentration to half may not translate to simply doubling the fixing time. Chemistry can be funny like that.

The shelf life of fixer is quite good, and it's really easy to check. If you're really having troubles with your fix getting old, don't mix up the whole batch next time.
 

I really wouldn't recommend mixing up only a portion of a bag of powdered fixer.

If you are going to try to vary your process from the manufacturer's recommendations, you will need to add additional test procedures to confirm that your materials are adequately fixed. Otherwise, over time, your results may degrade.

The costs and inconvenience of the additional tests will most likely exceed the benefit of the more dilute fix.

If however you are already performing those tests (to confirm proper fixation and washing) then I would say: experiment to your heart's content.
 
I would like to think Kodak know what they are talking about and probably have more collective experience than your friend. I can understand wanting to do it differently if it doesn't work, but as the saying goes "if it isn’t broken don't fix it".
 
You could save more money if you just skipped using fixer. Then you will really get what you are paying for.
 
MattKing said:
I really wouldn't recommend mixing up only a portion of a bag of powdered fixer.
Click to expand...

I don't necessarily think it's a great idea either, but if the powder is thoroughly mixed beforehand and carefully measured, it should be okay. I would think the margin of error would be less than diluting the fix and assuming it has linear properties, but I certainly wouldn't mix of portions of something more critical such as developer.
 
I'm assuming you'll get a bunch of "skimping on chemistry is false economy" responses, so let me be the first to agree with them

You are best off following Kodak's instructions to the letter.
Click to expand...

When one wants to try something new or unconventional, experts should be consulted beforehand. They will tell you that it can't possibly work and why. Then go and do it anyway ...

Or so the saying goes.

Dan, I don't suggest you dilute the fixer at will and suffer from stained negatives a few years down the road. What I do suggest is that you equip yourself with a retained Silver kit and see whether diluted fixer achieves archival fixing with the method you and your friend suggest. These kits are moderately cheap and easy to get, the last for a month or more and should give you plenty of opportunity to test your hypothesis. Either you find a way to make diluted fixer work for you (and save some money down the road), or you discover that after all is said and done, Kodak's instructions are the most efficient and economical way to fix your film.
 
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