Freezing C41 Chemicals

sirch

sirch

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I’ve had some Tetenal C41 mixed up and in use since around late January and it’s done a couple of rolls of 35mm, a roll of 120 and a number of single frames of 120 (for this project https://www.talkphotography.co.uk/threads/tin-can-selfies.692652/ ). As can be seen from the Campbell’s Soup photo in that thread the red is quite muted and I am assuming this is because the chemicals are starting to age, which is fair enough given how long I have kept them but they should be capable of plenty more rolls yet. I do use Protectan spray to force out the air .

As things stand I am doing around 1 of those frames per week so I was wondering if it is possible to freeze C41 chemicals when not in use? If so, would I need to freeze the blix as well as the developer or is blix not so prone to oxidation? To add insult to injury would it also be viable to microwave the frozen chemicals to thaw them out? If just sticking them in the freezer is not an option would getting them close to zero (e.g. ice bath in the fridge) make a significant difference?
 
To my knowledge it's oxygen that kills developer, not temperature, so I'd guess that freezing would make little difference. I'd suggest it would be better to keep the dev in a bottle that's made of material that is impervious to oxygen and can be squeezed to expel air. I use old PET bottles. I guess freezing would stop some oxygen getting to the chemicals in the same way it does with food? I was always hopeless at chemistry, so hopefully someone else will chime in on this.

It's the opposite with C41 bleach and blix: they both need oxygen to work properly, so you don't need to worry so much about that. Blix degrades because the bleach reacts with the fix. Kits with separate bleach and fix (such as the Fuji Hunt X-press kit) should last longer.

Don't forget to oxygenate your bleach or blix before use. It should be shaken vigorously for 30 seconds in a part-filled bottle. Repeat if it's not used for a week or so.
 
FujiLove said:
Don't forget to oxygenate your bleach or blix before use. It should be shaken vigorously for 30 seconds in a part-filled bottle. Repeat if it's not used for a week or so
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Thanks, that's good to know.

I didn't get on with chemistry at school either but I know that freeing some things can cause problems in terms of causing separation, crystal formation etc. I do wonder if keep transferring the developer to the tank and back into the bottle could be a problem because it obviously gets oxygenated. So there is a trade-off I guess, I am keeping the chemicals in the Jobo bottles and as I said using protectan gas to displace the oxygen.
 
Reducing the temperature will slow many chemical reactions, but I'm not sure the effect will be significant here.
The freezing point of aqueous solutions are often significantly below that of pure water.
This isn't the case for everything of course glacial acetic acid solidifies at around 20°C

Oxidation is the main issue, I would doubt the spray you're using actually displaces all the air, concertina style bottles are a much better option.
From the MSDS it seems protectan is basically butane. Highly flammable & not something I'd want to be storing in plastic bottles.
 
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Don’t freeze it. Once stuff comes out of solution it is not always simple to get it to dissolve again. Speaking from experience as a sometime and long ago biochemist. Heating up will also be problematic and microwave ovens are very localised in their heat distribution, speaking as an observant cook, even my morning porridge develops concentric rings where areas are hotter.
 
+1 for concertina type bottles if they are still available.
 
Freezing any solution causes the dissolved stuff to come out of solution. When you thaw the frozen solution you cannot expect the undissolved chemicals to dissolve in the correct sequence - or, perhaps, at all.
 
Thanks all,

Petrochemist said:
I would doubt the spray you're using actually displaces all the air
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I doubt that too but my limited understanding is that it is heavier than air and so forms a barrier layer between the developer and any air left in the bottle.


I have some concertina bottles but they won't fit in the Jobo so it would mean transferring the developer from the concertina bottle to the Jobo bottle, warm, use, return to concertina bottle which is more aeration both in the extra transfer and whilst it warming with air in the Jobo bottle.

I wonder if some sort of balloon (e.g. plastic bag loosely inflated) in the Jobo bottle would work – bit messy though. TBH all this is to some extent idle musings, after all I have got a couple of months out of the current batch. I guess what I really need to do is produce the photos faster and get more from one mixed batch in a shorter time scale.
 
Freezing stock C41 dev works well, I split my 5 litre mix into 1 L PET bottles, squeeze to exclude air and then vacuum pack each of the bottles I'm going to store. While biochems don't like freezing dilute organic solutions like this don't seem to suffer. (Biologist, turned analyst and later Occupational Hygienist ) The lower temperature will have an effect on oxygen transfer though the plastic layers. I don't freeze my working litre, just squeeze out air as much as possible and give a spray of Poundland Air-duster then into my fridge section of my photo fridge freezer. Bleach and fix stock live in fridge, working bottles in darkroom. I defrost new dev overnight , but if in a hurry do prewarm working dev from fridge for 2mins in microwave. The PET will harden after a while so don't do it often.

I don't use concertina bottles, past experience with a lab trying to use then for biological oxygen demand analysis proved disasterous.
 
It's a bit low tech, but what about some glass marbles? They are used in home brew to prevent oxygen reacting with beer/cider etc by filling up the bottle and removing the head space. Probably quite a lot of problems to consider though, like how much of a PITA they will be when emptying the bottle regularly.

Also, when using a plastic keg to hold beer, you pressurise the keg with carbon dioxide to carbonate the drink. Initially, you only add a small amount of carbon dioxide and then remove the keg lid, letting the heavier carbon dioxide displace the oxygen and preventing the beer from going bad, and then you put the lid back on and properly pressurise it. Not sure if there's a way to use carbon dioxide like this to give your chemicals a longer life?
 
Are you using C41 chemistry for B+W film?
 
dmb said:
Freezing stock C41 dev works well, I split my 5 litre mix into 1 L PET bottles
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Thanks David, that's really good practical advice. I had been avoiding the 5l kits due to the length of time it would take me to get through one but if freezing works then it would be a significant cost saving.

Carl Hall said:
It's a bit low tech, but what about some glass marbles?
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I use marbles in my HC-110 but it's not really an option with the working C41 developer because it is in and out of the bottle and tank and I think it would be a bit of a hassle trying stop the marbles going into the tank when pouring. The protectan spray works in the same way as the CO2 in the beer keg. David’s suggestion of pound-land air duster (which I assume is not air and knowing David I’m sure it isn’t) sounds a lot cheaper though.
 
sirch said:
I doubt that too but my limited understanding is that it is heavier than air and so forms a barrier layer between the developer and any air left in the bottle.
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Yes hydrocarbon gases are heavier than air, but they mix readily potentially producing an explosive mixture. Protectan in air is likely to be explosive anywhere between 1-10% volume. (Butane is 1.8-8% propane another major component is 2-10%)
Carbon di oxide would be a safer option but it will make your solutions more acidic so isn't suitable.
Argon would be ideal it's about the same density as butane and very inert, but it's moderately expensive (probably no more than Protectan which I'm sure has a huge mark up over LPG, which is what it actually is).
Nitrogen is what's generally used commercially for blanketing purposes, it cheap, & fairly inert. About the same density as air but once you've sealed container that makes no difference!
 
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Don't waste time with concertina bottles, they're basically unwashable. Use cheap PET bottles, squeeze out the air, and toss into the freezer. Only the dev really requires freezing, as unmixed Blix (or better yet, Bleach and Fix) will last very long.
 
Just a few things to pick up on:

Freezing and re-dissolving doesn't seem to be a problem, but make sure everything really HAS redissolved. It may take longer than expected and you may need to mix the container quite a long time (I would use a stirrer here but most homes don't have them).

Freezing will reduce oxidation rate, and oxygen will take much longer to diffuse through the ice block.

Concertina bottles wash fine, but need care and thoroughness. A quick sloosh with water won't work, and neither will careless draining afterwards.

Microwaving is probably fine "most" of the time, but may well degrade the dev unexpectedly. Don't do it unless your film doesn't matter.
 
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