Long, very long, lasting C-41 chemicals
I have been able to keep my C-41 working solutions to last for more than a year, almost 2 years. I thought I should share this method with everyone here. I hope this will encourage more people to develop their own color films which will lead to more consumption of C-41 films and as a result it helps film manufacturers (Kodak and Fuji) to make more due to the long lasting consumption in the market.
The benefit of being able to keep the C-41 chemicals for a very long time is mainly so that one can buy the chemicals in larger packages to achieve a much lower cost per unit of the chemicals without fearing that the chemicals will deteriorate and become unusable before they are used.
I am sure a lot of experts in this forum know the fact that the only chemical in a C-41 process that will go bad fairly quickly due to oxidation is the part C of the color developer. Everything else (Part A, B of developer, Bleach,Fix and Final Rinse) mixed or in concentrate will last just about forever. They do last for years to me and they don't seem to go bad any time soon. A unopened developer Part C will last 1 - 2 years but once opened it will oxidize in 2 -3 months even unused and tightly capped in the bottle. A mixed working developer solution will last only 2 -3 weeks.
This method is really a very simple one with a small extra cost. Just buy some CD-4 (Kodak color developer agent #4) in powder form available from Photographers Formulary. I do not know where else sells it so if anyone knows any other places please share them with us here.
I have quite a few expired C-41RA developer replenisher packages, each contains 4 sets of Part A, B and C to make 10 liters of C-41RA developer replenisher with each set, 40 liters total. All my Part C bottles have gone bad and are unusable. I simply mix the Part A and B per the mixing instruction but leave the Part C out (discarded). This is an incomplete C-41RA developer replenisher and It will last for years even mixed.
Before I use it I then mix this incomplete developer replenisher with C-41RA starter per the mixing instruction to make my incomplete C-41RA developer replenisher solution (still no Part C in it). I then add 5 grams of the CD-4 powder per liter of this incomplete developer solution to produce my C-41RA developer working solution. I only make one liter at a time so it will be completely used in a week or so. There is never any waste of it since it is completely used in a week.
As a result I am not only able to develop C-41 films that yields beautiful negatives I have been able to reuse it (with some replenisher added to top up the lost portion due to rotary processing by my Jobo processor). I have been able to reuse it 3 - 4 times with no or very small lost of quality. The CD-4 powder when buying in bulk will cost about $1.50 per 5 grams. I am sure it can be cheaper still when buying larger bulk each time. The greatest benefit is I no longer worry about my developer going bad any more. I can buy any large bulk developer packages and never worry that I will not be able to use all of it before it goes bad. I will use the Part C until it eventually goes bad then switch to use CD-4 powder. Cost of the developer are way down, despite that I have to buy large packages each time but they will last for years before I have to buy again. The bleach is not very cheap but it will last forever unused even opened. I buy it in large containers (5 liter bottle) and never waste any of it. All other chemicals are fairly cheap and also long lasting.
Well, there is one problem that I was once told. I also need to add something else in addition to the CD-4 powder. I have not seen any problems without it but I agree that there is another ingredient in the Part C that was discarded. Maybe because I am using C-41RA replenisher to begin with so it already has that missing ingredient in it. Perhaps I don't really need to add it. If so then I will just stick with developer replenisher always. Large developer packages are always sold in replenisher form any way. Just remember to buy some starter, which is cheap, too.
Hope this is useful info for everyone. Any comments/suggestions are welcome. Thanks.
Though some kits have that type of shelve life with no needed additions or modifications.
We are testing our kit at 3 months intervals, of open bottles, and so far are at 12 months. with the 15 month trial coming up shortly, and i have no doubt that the range of 18-24 months is not out of the question with this material.
I start with and keep liquid mixtures 'forever' (years and years) without any problem whatsoever. Read this and you will heed this:
Mix as per directions. I use Kodak Flexicolor, which is all liquid concentrates. Use PET plastic bottles (soda, Gatorade, almost all juices, etc) and fill them to the very rim. Cap securely. You could also use glass bottles and for small amounts of liquid I use either this or 50ml plastic liquor bottles.
You can even store the concentrates in these bottles if you do not wish to mix everything at once. Just be absolutely certain to fill to the rim, ESPECIALLY the "B" and "C" components of the Flexicolor chemicals. ("C is VERY easily ruined with oxydation.)
For BLIX I use a combination of film strength fixer plus potassium ferricyanide solution (1g PF in WTM 50ml). Just before use, mix one part film fixer (fresh) with one part PF solution. Make certain to stop thoroughly before blixing. - David Lyga
Something along the lines of the OP’s technique has been discussed before here. Personally I have used the technique of using 5 grams per liter of CD-4 to salvage C-41 developer I got from the lab I work at when part C went bad, and it works well. But I never tried mixing parts A and B and leaving out C and adding CD-4 when needed. It sounds like something worth trying. I have always just mixed everything at once and stored in glass jars filled to the top, with great longevity. All good ways to maximize usefulness of C-41 chemistry.
Thanks for commenting, David. Keep in mind that most PET (HDPE or LDPE) bottles are not oxygenproof. Kodak uses glass bottles for the Part C for this reason I believe. Everything else in a C-41 chemical kit will last a very long time (years) if not forever. Most people are forced to buy small C-41 kits because of the short lived Part C issue. But small kits are far more expensive. As a result some people simply shy away from processing at home and are forced to accept mediocre commercial processing.
Originally Posted by David Lyga
I am able to purchase developer packages that are primarily for commercial labs that are far cheaper per unit volume of the developer. The Part C bottles will go bad but I don't care. I simply use powder CD-4 instead. I am very happy that I no longer worry about my developer going bad. I am able to use up to the last drop of it no matter how long it takes me to finish up all the developer from the package.
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Can't wait to hear from PE, wondering of this technique can be applied to E-6 as well...
Here's an option you might want to try to eliminate oxidation in partially filled bottles. I came across a "Swissmar Epivac" system at a yard sale. It consists of a small hand-operated vacuum pump and special black rubber stoppers. You simply insert a stopper in a glass pop/soda bottle and then start the vacuum creation with the pump. There is a small "wick-like" stem that sticks up in the center of the rubber stopper. To release the vacuum you just push this wick-like stem to the side - you'll here the air rush in. I bought a dozen extra stoppers thru Amazon. Test the stoppers beforehand to make sure you don't get a dud. I haven't been able to make use of mine yet but I would think they should work - they seem to hold vacuum very well.
You know, I cannot definitively state whether PET is fully oxygen proof. But I will say this: if filled to the very rim, you need not worry. At least I don't after having this stuff stored, diluted, for literally YEARS. That has to mean something. It is interesting to discuss this and it comes up rather often. All I can do is relate my experiences to all. Yes, that part C is a very difficult liquid to keep good, but even that works with the PET in my experience.
An interesting note: the PET has a strange quirk though. I have noticed that after maybe one year of unpoened storage there is SLIGHTLY less in the bottle. It is as if there has been slight evaporation!!! I am talking about only, perhaps, 2% of the entire liquid, but it leaves a slight gap in the bottle. HOWEVER, that gap is NOT filled with oxygen. ONLY IF YOU OPEN that bottle do you then have to insert marbles in order to displace that new oxygen. - David Lyga
I keep all of my working solutions for upwards of a year. When I bottle them, I bottle them warm to keep as much oxygen out of them as possible. Then put them in plastic beer bottles from the brew shop. I squeeze the bottle to get my solution up to the very top and cap it. Once the solution cools down and condenses, it creates a vacuum seal as well.
That's a good plan, hmm perhaps chemistry "canning" is an option... Those ball jars are cheap!
Originally Posted by WayneStevenson