Storage life of unmixed C41, E6 developing kits?

GRHazelton · Jul 9, 2013

Considering the rapid disappearance of color films both slide and negative and contemplating the sizeable store of such in my freezer, I wonder if I should stockpile E 6 and C 41 processing kits. Does anyone have any thoughts about the shelf life of unmixed, factory sealed kits? Would refrigeration, NOT FREEZING, extend their shelf life? Its ironic. When I am finally able to afford used the gear I once only could dream of, the film to use in them becomes scarce. I would hate for my Pentax 645n kit, my LX's, my Retina IIIc, my Vitessa L to languish for lack of "fuel."

David Lyga · Jul 9, 2013

Again: keep in either glass or clear plastic bottles (soda, juice, water, etc) FILLED TO THE RIM. Use glass marbles to take up the slack. I am talking 'indefinitely' as to the time you can keep them. In other words: forever. Period. When I am buried you may have my remaining C-41 dev and RA-4 dev. Few believe this solution for preservation. - David Lyga

GRHazelton · Jul 9, 2013

David Lyga said:
Again: keep in either glass or clear plastic bottles (soda, juice, water, etc) FILLED TO THE RIM. Use glass marbles to take up the slack. I am talking 'indefinitely' as to the time you can keep them. In other words: forever. Period. When I am buried you may have my remaining C-41 dev and RA-4 dev. Few believe this solution for preservation. - David Lyga

Many thanks for the quick response. It sounds as though you are describing ways to store already mixed and perhaps already used solutions. Good to know! I've also heard it suggested that displacing the air above the solutions with something without oxygen, propane, butane, canned "air" is efficacious. I would guess that the choice of plastic bottles might be significant, since I've read that some plastics allow diffusion of gases through the plastic.

Any thoughts on refrigeration?

heterolysis · Jul 9, 2013

The colder it's kept, the longer the shelf life, theoretically.

Are you talking about powders or liquids?

Liquids will benefit greatly from being kept cold. Powders it won't make much of a difference. Liquids in a fridge will be roughly 20C below room temperature and should theoretically last 2^2= 4 times as long as their listed shelf life, if they have one. And this is probably a gross underestimate of it, since they live longer than shelf life to begin with.

Vacuum sealed powders will probably last forever.

GRHazelton · Jul 9, 2013

heterolysis said:
The colder it's kept, the longer the shelf life, theoretically.

Are you talking about powders or liquids?

Liquids will benefit greatly from being kept cold. Powders it won't make much of a difference. Liquids in a fridge will be roughly 20C below room temperature and should theoretically last 2^2= 4 times as long as their listed shelf life, if they have one. And this is probably a gross underestimate of it, since they live longer than shelf life to begin with.

Vacuum sealed powders will probably last forever.

Liquids. I seem to recall from college chem courses that chemical activity roughly doubles with each 10 C rise in temperature. This would suggest that each comparable drop in temp would halve deterioration, although enough drop might precipitate components which might then be difficult to redisolve. So, with the proper temperature for a fridge being perhaps 35 F what will precipitate out, and can it be re-dissolved? Any experience out there? I know that some formulae for developers specify the temperature of the solute and the order of addition of components; this suggests that cooling below STP might be deleterious.... Any photo chemists out there who might weigh in?

polyglot · Jul 9, 2013

Do not open them! They are packed under nitrogen in the factory and far better sealed and protected from oxygen than you can manage at home. Glass, marbles, butane and all that bullshit is useful only once you have opened containers.

Refrigeration certainly helps on the mixed up solutions, but they do have oxygen available to them in the solution water. It may or may not help with concentrates depending on how well they're packed and if they're using water or TEA as the solvent, i.e. on the availability of things that the active ingredients can react with. If you're going to refrigerate, only bother with the developer parts (and maybe E-6 reversal+pre-bleach) because the bleach, fix, etc won't really go off. Handily, those parts are physically much smaller.

Powders will last the longest of course. Up to you whether the processing quality of powder kits is sufficient, as they tend to be blix kits.

The other thing is that the chemistry is all available as component chemicals. I've never DIY'd it myself but there are people here who have and I wouldn't expect it to be particularly difficult as long as you can physically buy the right chemicals.

Tom Taylor · Jul 9, 2013

Yesterday I developed a roll of expired (7/11) Ektar 100 film that I shot over the weekend. The film was kept refrigerated in the wine cooler so I wasn't too concerned about the film; but I was as bout the Kodak C-41 developer kit which I originally opened on 1/1/2011 - two and a half years ago! I went on the Kodak web site to consult the Tech Pub that tells you how to determine the condition of the chemistry by their coloration. The colors indicated that the chemistry was good and the roll turned out fine although I haven't printed the negatives yet. This was the Kodak 5 gallon kit and the bottles have "0833" stamped on them which may mean that they were mfg during the 33d week of 2008. I was also concerned about the C-41 fix which I first opened on 5/10/2009 and the date stamped on it is "0814."

Thomas

PS: The chemistry above was not kept refrigerated nor was there any attempt to shield the contents from oxygen other than keeping them tightly caped.

AgX · Jul 10, 2013

polyglot said:
Do not open them! They are packed under nitrogen in the factory and far better sealed and protected from oxygen than you can manage at home. Glass, marbles, butane and all that bullshit is useful only once you have opened containers..

A glass container would be diffusion-tight in contrast to an original plastic container.
It is possible (though a hassle) to refill chemistry from one container to another without losing a nitrogen topping.

polyglot · Jul 10, 2013

AgX said:
A glass container would be diffusion-tight in contrast to an original plastic container.
It is possible (though a hassle) to refill chemistry from one container to another without losing a nitrogen topping.

The original plastic containers (at least, the ones I've received from Fuji) are HDPE, which is quite impermeable. The oxygen dissolved in the water that the concentrates are made up in is far greater than the oxygen that can diffuse through the container.

Anything that someone does at home is going to ruin the nitrogen filling and run far greater risks than just leaving the chemicals in the manufacturer's containers.

Once you've opened the containers of course, by all means transfer stuff to glass bottles etc. The concentrate containers often don't seem to seal very well once the thermal seal is broken.

heterolysis · Jul 10, 2013

I don't think anyone really needs to worry about whether the plastic is permeable to oxygen or not...

But if you feel like transferring to glass bottles, sparge the solutions thoroughly with an inert gas afterwards. Fill a balloon with nitrogen or another inert gas, then tape the opening over a small rubber tube. Bubble the gas through the solutions and they'll be fine afterwards.

GRHazelton · Jul 10, 2013

heterolysis said:
I don't think anyone really needs to worry about whether the plastic is permeable to oxygen or not...

But if you feel like transferring to glass bottles, sparge the solutions thoroughly with an inert gas afterwards. Fill a balloon with nitrogen or another inert gas, then tape the opening over a small rubber tube. Bubble the gas through the solutions and they'll be fine afterwards.

Since nitrogen is hardly an inert gas, can you suggest alternatives more readily available without going to a gas welding shop? Butane, propane, dust off or canned air gas?

polyglot · Jul 10, 2013

Gas diffusion through bottles is the ONLY reason to transfer stuff to glass. LDPE for example is completely unsuitable for storing developers, but HDPE and PETE are fine.

Nitrogen (N2) is quite unreactive, certainly as far as photo chemicals are concerned. Seriously, no one is going to do a better job of packaging chemicals than the factory, unless it's those Digibase lids that would fall off in transit.

If you're gas-filling at home, hydrocarbons (butane lighter refill) is the easiest option. Heavier gases are better though and I think Protectan is something like a CFC.

AgX · Jul 10, 2013

Protectan is Butane by now.

heterolysis · Jul 10, 2013

GRHazelton said:
Since nitrogen is hardly an inert gas, can you suggest alternatives more readily available without going to a gas welding shop? Butane, propane, dust off or canned air gas?

Go to the party shop and get helium instead.

Nitrogen is an inert gas under almost any circumstances---butane and propane are not, but are suitable for storing chemicals. Nitrogen is lighter than oxygen, so it will not blanket your solution for any length of time, though you shouldn't put much faith in any gas doing so. We use nitrogen and argon for all of our air-free chemistry at work.

ambaker · Jul 10, 2013

Nitrogen is relatively inert. It does combine with oxygen, NOx for dragsters etc.

Argon is not only completely inert, it was the cover gas of choice for liquid sodium breeder reactors, it is heavier than air.

Both should work well for oxygen exclusion in photo chemical preservation. Though, theoretically Aragon a bit better due to being completely inert, and heavier than air.

Sent from my iPad using Tapatalk HD

polyglot · Jul 10, 2013

ambaker said:
Nitrogen is relatively inert. It does combine with oxygen, NOx for dragsters etc.

N2 and NOx are very very different beasties. N radicals have huge reaction energies because N2 is at such a low-energy state. In other words, the very-inert nature of N2 (difficulty in making it react without bringing it up to very high temperatures and/or using catalysts) is the very thing that makes N compounds (NOx and azides for example) so powerfully reactive.

ambaker said:
Argon is not only completely inert, it was the cover gas of choice for liquid sodium breeder reactors, it is heavier than air.

Argon is an excellent choice, but harder to find (in small, affordable quantities) than butane for most people. It's hard to beat a $3 can that will last 5 years of topping off bottles...

ambaker said:
Both should work well for oxygen exclusion in photo chemical preservation. Though, theoretically Aragon a bit better due to being completely inert, and heavier than air.

Butane is quite a bit heavier than Argon. Still, I expect that at STP in a little bottle, the gases will be pretty well-mixed anyway just thermally. Note that N2, O2, Ar and CO2 in our atmosphere are all really uniformly mixed despite some big differences in nominal density.

Either way, a nice trick is to put in a couple atmospheres worth of the inert gas then let it down to near 1 atmosphere. That will reduce the partial-pressure of oxygen even further.

David Lyga · Jul 15, 2013

PET plastic is amazingly resistent to oxidation and it is as available as your nearest trash can. Almost all soda, juice, etc are packed in this clear, brittle plastic with a very secure cap. FILL TO THE VERY RIM with either concentrates or mixed developer. Room temperature is fine. Tiny, 50ml liquor bottles (metal cap) are fine for smaller amounts and there are even tiny glass marbles (in case the larger ones do not fit) that are available in Arts and Crafts stores. - David Lyga

Storage life of unmixed C41, E6 developing kits?

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