Black Sediment In Fixer With Flakes

[braxus]

I developed a roll of Fomapan 400 (Arista EDU Ultra) and after that roll, I noticed my fixer was quite black, with black flakes sedimenting on the bottom of my cup. I poured it all out and you could see the black flakes on the sink bottom. What is this? Does this mean I should have pre-rinsed my film?

 

[MattKing]

Most likely it is silver that is plating out, and your fixer needs to be replaced.

 

[braxus]

Ok. Its good I dumped it then. And I just bought a fresh new bottle of fixer on Saturday too. What is plating out?

 

[RalphLambrecht]

Ok. Its good I dumped it then. And I just bought a fresh new bottle of fixer on Saturday too. What is plating out?

elemental silver; this is pure silver. Congrats! You are into precious metals now. You could investigate silver recovery units and sell the stuff, but don't give up your day job quite yet!

 

[koraks]

What is this?

Keeping around working stock fixer for too long, allowing to oxidize, as well as overusing it far beyond its stated capacity.

What is plating out?

It means that the silver that's dissolved in the fixer in the form of soluble silfer-thiosulfate complexes starts to precipitate in the form of metallic silver. It often deposits as a thin film of silver inside the container it's in if it's left to sit undisturbed - hence the term 'plating out', because the effect is similar to electroplating e.g. nickel or chrome (and the chemistry involved is in fact conceptually similar, too).
In your particular case, it's not just plating out, though. The fixer looks cloudy with yellowish tones, which suggests it's also sulfuring out. I.e. elemental sulfur is being formed that floats around in the liquid in the form of tiny particles.

All of this suggests that I mentioned above - that the fixer has become unstable due to overuse and oxidation. It's best to keep good notes on the amount of use working stock fixer has seen, and not to keep it around for too long even with mild use. When storing used fixer, it helps to keep it in a sealed container with little or no air on top of the liquid.

 

[Don_ih]

The upshot, however, is that you need to refix your film. And check the most recent ones, too.

 

[AERO]

elemental silver; this is pure silver. Congrats! You are into precious metals now. You could investigate silver recovery units and sell the stuff, but don't give up your day job quite yet!

Yep..just $29 an ounce where as gold hits $2642 an ounce. this a.m 02/01 Top o' the world Ma!!

 

[Andrew O'Neill]

Good thing film isn't made of gold then!

 

[DeletedAcct1]

I developed a roll of Fomapan 400 (Arista EDU Ultra) and after that roll, I noticed my fixer was quite black, with black flakes sedimenting on the bottom of my cup. I poured it all out and you could see the black flakes on the sink bottom. What is this? Does this mean I should have pre-rinsed my film?

Don't reuse fixer, use it one-shot. May be overcautious but this way you're not ruining any film...

 

[MattKing]

Don't reuse fixer, use it one-shot. May be overcautious but this way you're not ruining any film...

On this, we disagree.
Although I do recommend diligent monitoring of the status of fixer. I do a clip test every time I fix film, and track use vs. recommended capacity.

 

[Doremus Scudder]

If your fixer is throwing that much silver precipitate, it is likely way, way past it's useful life and you've been underfixing things for a while now.

Read up on fixers and capacities and learn how to do a clearing test. Ilford's tech sheets are extremely informative.

Best,

Doremus

 

[MattKing]

My clip test Resource is here: https://www.photrio.com/forum/resou...ixing-procedure-for-black-white-negatives.75/

 

[braxus]

Its weird because even the most recent films I did look completely clear with no fog. Oh well. I'll try to mix up a fresh batch. I didnt think I did that many films in this fixer batch, though it has been sitting for quite some many months inside a capped/ sealed 1L container.

 

[MattKing]

Its weird because even the most recent films I did look completely clear with no fog. Oh well. I'll try to mix up a fresh batch. I didnt think I did that many films in this fixer batch, though it has been sitting for quite some many months inside a capped/ sealed 1L container.

It happens.

 

[Ivo Stunga]

Don't reuse fixer, use it one-shot. May be overcautious but this way you're not ruining any film...

For me 500ml hypo fixer works for 10 reversed BW films. Then I change it. Last couple of films just need a minute or two longer fix time.

Although I have 25kg bag of sodium thiosulfate and could do one-shot.

I often have similar sediment and coloring in 1st developer (with some hypo) that I keep around for a few weeks whilst it keeps waiting for 2nd film.

 

[koraks]

many months

Yeah, that's not a great idea, obviously.
Fixer can (seemingly) 'topple over' virtually instantly. What happens in reality is that the sulfite present to protect the thiosulfate from oxidation gradually is turned into sulfate through the influence of oxygen. At some point, the sulfite gives out and then the thiosulfate starts to degrade. At this point, the fixer (with its suilver-thiosulfate complexes and all) becomes chemically unstable and as a result, things can go south seemingly very rapidly all of a sudden. In reality, the decay is gradual, but it's a kind of metastable system, which makes it seem more instantaneous than it really is.

 

[Don_ih]

Fixer can (seemingly) 'topple over' virtually instantly.

I had that happen with one of my paper fixers a few weeks ago (I use two trays of fixer for paper and keep them in sealed containers when not in one). One day, the fixer had suddenly turned murky - almost black-looking.

Its weird because even the most recent films I did look completely clear with no fog.

You need to reexamine those films in the midtones. Spent fixer has little difficulty fixing unexposed film but has significant difficulty in moderately exposed film. Unfixed midtones look weird when tipped at an angle to the light. They look odd in a scan, too (kinda glowy). Also, the not-fixed-out undeveloped silver may take some time to become visible.

 

[RalphLambrecht]

Don't reuse fixer, use it one-shot. May be overcautious but this way you're not ruining any film...

That's one of the painful lessons I learned as well

 

[Sanug]

Don't reuse fixer, use it one-shot. May be overcautious but this way you're not ruining any film...

This is wasting fixer. Not needed and not a good idea.

 

[DeletedAcct1]

For me 500ml hypo fixer works for 10 reversed BW films. Then I change it. Last couple of films just need a minute or two longer fix time.

Of course Ivo, in a reversal setting the fixer is much more preserved in terms of capacity since it has to fix way less that a negative film.

 

[DeletedAcct1]

This is wasting fixer. Not needed and not a good idea.

You should add "in my opinion"...

 

[DeletedAcct1]

That's one of the painful lessons I learned as well

In 30 years that I develop and reverse films I've never ever had one single problem using the fixer one-shot.

 

[Sanug]

Sure. I believe that you did not have any problems when discarding fixer after each roll of film. But I still insist that doing so is an unnessessary waste of material.

I use 600 ml of Adofix Plus 1+4 for 10 rolls of film (no T-grain films) within half a year. The clearing time never exceeds 1 minute. I never had any problem with my films or with flakes in the dilution.

 

[MattKing]

In 30 years that I develop and reverse films I've never ever had one single problem using the fixer one-shot.

Same applies to me, in my decades of carefully re-using film fixer - almost exclusively rapid fixer.

 

[JerseyDoug]

Yeah, that's not a great idea, obviously.
Fixer can (seemingly) 'topple over' virtually instantly. What happens in reality is that the sulfite present to protect the thiosulfate from oxidation gradually is turned into sulfate through the influence of oxygen. At some point, the sulfite gives out and then the thiosulfate starts to degrade. At this point, the fixer (with its suilver-thiosulfate complexes and all) becomes chemically unstable and as a result, things can go south seemingly very rapidly all of a sudden. In reality, the decay is gradual, but it's a kind of metastable system, which makes it seem more instantaneous than it really is.

Thank you! Finally an explanation of what happened to me couple of times when I was less careful than I am now about recording how many rolls of film I've put through a quart of fixer.