Black fallout in Ilford Rapid Fixer?

Okay, so I'm a bit of a cheapskate, and I use old fixer, but hear me out.

A couple of days I went to fix some film I had just developed and went to pour up some fixer I had mixed a year or so ago, and it was full of these black flakes. I didn't think too much about it, since I use the 2-bath system, and poured it back into it's bottle and went for my second bath instead which after a clearing test proved fine so I used it.

Then a day later I noticed the same black flakes in my other bottle of fixer, not as much as in the other bottle but still a bit. I decided to mix a new batch from my trusty concentrate bottle (from 2008 if I remember correctly), and fixed in that instead. I also went to buy a new bottle since the old one finally ran out. After that I also poured out the new mix into my steel-wool canister and mixed some fresh fixer.

Anyhow, any ideas on what might cause these black flakes? I quite fascinated by chemistry so it would be nice to know.

Silver.

So when the fixer get old, it can't hold the silver in solution?

I my experience, it does not even need to be that old. I think it has more to do with how much silver has been dissolved. I do not have any evidence that the black flakes are harmful but, I usually try to use a filter when pouring used solution back into the storage bottle.

Okay, I though it was the end of my fixer, I'm gonna get a pack of filter paper and filter it out next time.

Fixer does not keep forever. It keeps better than most developers, but you still need to be somewhat careful.

For example, partially filled concentrate bottles can go bad as quickly as just one year, so if yours was from 2008, you have been lucky, or you have squeezed all air out. You will see it going bad when white gunk (sulphur) starts to appear.

Used fixer with dissolved silver in it won't keep well no matter what you do. You should replace it every few months. It may be OK for 6 months but not much more. Usually, something like 2-3 months is recommended. Soon, black gunk (silver) starts appearing. It starts depositing on the bottle walls and is hard to remove -- you can use Farmer's reducer (or a color bleach, then fixer), or a reversal B/W bleach to clean it.

I have heard that using an overused fixer even as a first bath can cause formation of harder-to-dissolve silver-thiosulphate complexes to the emulsion, making it difficult for the second fixer bath and wash. I'm not sure about this, but if this is true, then it would mean that even in 2-bath fix process, you need to have two (somewhat) GOOD fixers. It will still save some fixer. Anyway, if the first bath is dead, you will anyway depend solely on the latter one, nullifying the benefit of 2-bath.

Filtration can fix the symptoms, but it does not help if the fixer has gone bad or lost its power. So, it's better to buy new fixer when silver appears. Fixer is not that expensive...

hrst said:

Fixer does not keep forever.......it [is] going bad when white gunk (sulphur) starts to appear [in the concentrate]

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This is the bigger problem for me. The concentrated stock solution goes bad before I've used it all. After having to throw out about a quarter of the last gallon of stock I had, I decided the fixer is cheap and there is not really any point in pushing its capacity if that means the stock rots and has to be wasted.....so, I've recently taken to using fixer for only about five rolls or less. I always use fresh fix for prints.

The presence of the dark deposit on the side walls of the bottle doesn't seem to depend solely on the throughput of film, but more on age. It doesn't seem to affect the clearing time. Whilst I would always use fresh fixer for important work, I've never experienced any issues with using elderly fixer. Last weekend I was looking at some prints I made in about 1970, when virtually every item of material and chemical was outdated because that was all I could afford as a schoolboy. They were no worse than when I printed them, and actually remarkably good, all things considered. I also reflected on the fact that in those days of having no cash, I only ever used one fluid ounce of print developer (Johnson's Contrast). To use two fl. ozs. would have been most extravagant!
Steve

I've had issues with this in the past, flakes of silver floating around in an old accordion bottle which was used for a long time.
- So I basically ruined fresh fixer by re-using the old, messy bottle.

When I fix, I agitate pretty hard, so I experienced very small scratches in the emulsion from the flakes (seen on very big enlargments and scans), and I also experienced a real mess of small silver-grains being embedded into the emulsion.

It was so bad that these negatives were unprintable, in fact, after scanning, I had to invent a pretty advanced photoshop automatic spec removal action, because cloning out all the specs took hours upon hours.

After changing bottles and filtering my fixer trough 5 coffee-filters, I've had no issues at all.

I like to mix fixer from powder (Foma has a great 1 liter pack), so I have no stock solution that can go bad (I don't shoot miles of rolls though).

So am I understanding the best way to keep your fixer free of the silver flakes is to run it through a few coffee filters before putting it back in the storage tank?

I have experienced this same problem. Thanks

~M

Overuse of fixer effects the stability of the negatives.

Something to be careful of is that the silver can coat the inside of the bottle - you can chuck the fixer and refill with fresh, but often the flakes remain and eventually break free and contaminate the fixer, regardless of how old it is.

I got caught by this recently, dark specs stuck in the emulsion of the film due to the silver coating on the inside of the glass deciding to come off for no obvious reason into my fresh fixer....

It is a good idea, therefore, to check and clean or replace your bottle periodically.

Not a problem with the dark brown one liter glass bottles meant for chemicals I'm using, I first slosh them out with a 100 ml of new fixer, then hot water. The fixer takes care of the black flakes, and hot water readily dissolves the white powdery stuff you sometimes get floating in your fixer (sulphates?). Also being glass means you can actually check if they are dirty or not, and they are easy to clean, and the cost a couple of euros per bottle, compared to like 7-10 € for an accordion bottle.

mr. mohaupt said:

So am I understanding the best way to keep your fixer free of the silver flakes is to run it through a few coffee filters before putting it back in the storage tank?

I have experienced this same problem. Thanks

~M

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Coffee filters worked fine for me, but I wetted the filters first, rinsing them slightly in water, because the paper can sometimes be "dusty", so I didn't want the coffee filters to leave anything behind.

Also, of the 5 filters, I used one single run and then 2 more runs with double filters.

And I poured everything into a new and clean drinking bottle, it's cheap and it's easy to check for impurities, never had a problem since.