Mould/fungus growth on odourless fixer

Fatih Ayoglu · Mar 10, 2024

Hi all,

I have not used my BW printing Nova processor for few weeks, the lids were on, also the processor top was wrapperd with cling film to prevent any air getting in.

Yesterday I’ve checked and realised my fixer had mould/fungus growth in it. That slot has Fotospeed Odourless fixer. Another slot has old Ilford Fixer, not an issue in that.

So I’m wondering if odourless fixer does not have a crucial anti fungus chemical or something else is going on. I believe I can filter the fungus and keep using the fixer as it is still in good condition but still wondering why it is fungus growth.

Many thanks,
Fatih

john_s · Mar 10, 2024

Odorless fixers have pH near 7. Acid fixers smell of SO2 and alkaline fixers (rapid fixers) smell of ammonia. So the odorless ones are in a "sweet spot" in between. I'm guessing that near neutral pH is facilitating the mould growth. Maybe there's something you could add to control the fungus.

koraks · Mar 10, 2024

Fatih Ayoglu said:
I have not used my BW printing Nova processor for few weeks

You leave it sitting like that with the chemistry in? Is that...recommended? I imagine you get a lot of silver plating on the walls of the fixer slot, for starters.

And yes, mold. There's very little in fixer to stop mold growth, unless the fixer has been used, in which case the silver may help some. But I'm not surprised it grows all kinds of nasty. I'd just drain the processor when it's not being used for more than a day or two.

Fatih Ayoglu · Mar 10, 2024

koraks said:
You leave it sitting like that with the chemistry in? Is that...recommended? I imagine you get a lot of silver plating on the walls of the fixer slot, for starters.

And yes, mold. There's very little in fixer to stop mold growth, unless the fixer has been used, in which case the silver may help some. But I'm not surprised it grows all kinds of nasty. I'd just drain the processor when it's not being used for more than a day or two.

Yes you can keep it for a long time. Of course if you use, it will help airing the chemicals maybe that will avoid otherwise no issue with keeping chemicals inside.

PS I bottle RA4 chemistry though

Fatih Ayoglu · Mar 10, 2024

john_s said:
Odorless fixers have pH near 7. Acid fixers smell of SO2 and alkaline fixers (rapid fixers) smell of ammonia. So the odorless ones are in a "sweet spot" in between. I'm guessing that near neutral pH is facilitating the mould growth. Maybe there's something you could add to control the fungus.

I have few powder chemicals, or maybe a drop of consumer grade bleach

koraks · Mar 10, 2024

Fatih Ayoglu said:
it will help airing the chemicals

Not sure if we have the same understanding of what 'airing' means, but neither developer or B&W fixer wants to be oxidized. You want to limit airing of both solutions - which I understand is one of the benefits of the Nova, since the air/fluid interface is fairly small.

Fatih Ayoglu said:
PS I bottle RA4 chemistry though

Yeah, good idea, especially the developer. The blix can take a bit more abuse.

mshchem · Mar 10, 2024

I suspect having a little bit of oxygen wouldn't hurt. Maybe skip the cling wrap.

I never leave chemistry in anything. put back in a bottle.

john_s · Mar 10, 2024

koraks said:
You leave it sitting like that with the chemistry in? Is that...recommended? I imagine you get a lot of silver plating on the walls of the fixer slot, for starters.

And yes, mold. There's very little in fixer to stop mold growth, unless the fixer has been used, in which case the silver may help some. But I'm not surprised it grows all kinds of nasty. I'd just drain the processor when it's not being used for more than a day or two.

That reminds me. There is a thread here at photrio somewhere where someone who mixes his own fixer has stated that it keeps better if it has been used even a little because of the silver being a biocide. To the OP, have you noticed the mould in fixer that has been used?

Fatih Ayoglu · Mar 10, 2024

koraks said:
Not sure if we have the same understanding of what 'airing' means, but neither developer or B&W fixer wants to be oxidized. You want to limit airing of both solutions - which I understand is one of the benefits of the Nova, since the air/fluid interface is fairly small.

Yeah, good idea, especially the developer. The blix can take a bit more abuse.

Airing: time to time using so the chemical in the slot is mixed

Regarding RA4 dev: it was your recommendation

Fatih Ayoglu · Mar 10, 2024

john_s said:
That reminds me. There is a thread here at photrio somewhere where someone who mixes his own fixer has stated that it keeps better if it has been used even a little because of the silver being a biocide. To the OP, have you noticed the mould in fixer that has been used?

Yes that odourless mixer is used, specifically with Ilford FB paper. Yes mould
The odour mixer (Ilford) is also used, with Ilford RC paper. No mould

Fatih Ayoglu · Mar 10, 2024

mshchem said:
I suspect having a little bit of oxygen wouldn't hurt. Maybe skip the cling wrap.

I never leave chemistry in anything. put back in a bottle.

Yes I might skip the cling film. In any case, because inert chemical (the part that goes off) will be on top, and oxygen won’t pass certain thickness of inert chemical, it might be ok not to use cling film

DREW WILEY · Mar 10, 2024

Water mold (Saprolegnia) spores are everywhere, and you can easily get it in old dilute fixer or reused Photoflo solutions,
even distilled water if left uncapped. A tiny bit of true thymol ingredient Listerine will solve it; but I don't know if that will have any kind of negative effect on your film or paper or not. I don't re-use solutions; period. Dye tranfer printing dyes were an exception, because you can re-adjust the pH, and I did use thymol in those, or else they have to be routinely filtered.

Maris · Mar 10, 2024

My Fotospeed FX-30 odourless fixer working solution diluted 1+4 from the concentrate has been mould free since it was mixed on January 6th this year. Previous batches also stayed mould free.
On the other hand dilute Fotospeed SB-50 odourless stop bath (based on citric acid) definitely grows mould even in my well scrubbed darkroom. As Drew Wiley indicates the mould spores are everywhere, just not in my fixer at least for now.

Fatih Ayoglu · Mar 10, 2024

I wonder if tiny amount of cleaning bleach would solve this problem

DREW WILEY · Mar 10, 2024

Bleach can potentially be a serious problem. I wouldn't go there.

Kino · Mar 10, 2024

I leave my Nova full all the time with the cling film. Yes, mold forms on the ends of the stop bath cover tube. I just remove the cling film, drop the level of the tank a bit, wipe it down with paper towels and give the slot a good examination. If there is mold growing in the stop itself, drain, flush and fill with new stop.

Mold spores are everywhere and refilling and stabilizing the heater temperature on my Nova takes about 24 hours.

Not worth it.

Rick A · Mar 10, 2024

Fatih Ayoglu said:
I have few powder chemicals, or maybe a drop of consumer grade bleach

NO to bleach. Wash everything down with 3% hydrogen peroxide, you can put it in a spray bottle and spritz the room with it. I had a mold problem in my darkroom when I first built it in a corner of our basement, I killed it with peroxide.

Kino · Mar 10, 2024

Now you CAN and SHOULD put about a teaspoon of bleach in the heater water jacket to prevent mold growing in there, but not in any areas where the paper chemistry resides.

In about a month, I am going to do my annual purge and flush of the Nova. Totally clean it out both slots and heater jacket water and refill it.
But since I am running replenished LPD and using TF5 for fixer, it goes right back in...

mshchem · Mar 10, 2024

Why not use Ilford rapid fixer for both fixing bathes?

DREW WILEY · Mar 10, 2024

There are all kinds of mold inhibitors available, but few of them are suitable for actual photographic solutions.

pentaxuser · Mar 11, 2024

koraks said:
You leave it sitting like that with the chemistry in? Is that...recommended? I imagine you get a lot of silver plating on the walls of the fixer slot, for starters.

I have always found with my Nova that household bleach does a great job with silver plating on the walls, clearing it in usually less that a day However a silver sludge does form on the bottom of the slot which is black rather than the white of the walls and this takes much longer to remove and can involve scrubbing it with a bristled bottle brush

A 1+1 or even neat household bleach- just enough to cover the bottom - may work more quickly but I haven't tried that

pentaxuser

koraks · Mar 11, 2024

pentaxuser said:
However a silver sludge does form on the bottom of the slot which is black rather than the white

A white precipitate on the walls is not silver plating/silvering out. Silver plating is always black or very dark brown when viewed head-on and shiny/silvery when viewed through a transparent and perfectly smooth substrate such as glass or perspex (a.k.a. "a mirror"). The white precipitate a fixer leaves on the walls of a container will be something like finely divided sulfur (which is near-white) and can also be drying spots of sulfite etc.

To remove the silver you could try a rehalogenating silver bleach and then fix it out (i.e. Farmer's reducer) or a more aggressive (and therefore nasty, health/environment-wise) reducer such as something involving dichromate or permanganate. If scrubbing works for you, that's evidently a safe method. Or one could accept it as a matter of course and just ignore it; it won't do much harm as the silver layer is virtually inert.

Fatih Ayoglu · Mar 11, 2024

mshchem said:
Why not use Ilford rapid fixer for both fixing bathes?

I was trying to avoid the smell but maybe I should go back to Ilford Rapid, the capacity is higher with that as well

mshchem · Mar 11, 2024

Fatih Ayoglu said:
I was trying to avoid the smell but maybe I should go back to Ilford Rapid, the capacity is higher with that as well

One less chemistry to keep on hand.

john_s · Mar 15, 2024

Would the presence of borate in fixer prevent mould? I notice that Ilford Hypam Rapid Fixer has three acidic components: bisulphite (sulphite is essential for stability), acetic acid and boric acid.

I have read that in addition to dealing with ants (and termites in this part of the world), borates prevent fungus. Would this be the reason for the difference between the OP's problem with one bath and not the other?

Mould/fungus growth on odourless fixer

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Mould/fungus growth on odourless fixer

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