E6 Colour Chemicals
A lot has been said about prolonging the life of film by freezing it or putting it in the fridge, but what about colour processing chemicals? I am thinking of E6 reversal in particular.
I use a bit of E6 film but would use more if I could buy a kit to do it myself. Opened bottles of the chemicals have a limited shelf life because they absorb oxygen and 'go off', but if they were deep frozen how would they be able to absorb anything, so prolonging their shelf life.
I am not talking about part used dilutions here, I always use once and throw away, it is just the part empty bottles of concentrate. What are the views on this?
Many threads about this on APUG, just do a search.
The juice is:
Freezing: some say it works; might leave crystals on the bottom; producers discourage it.
Topping bottles with propane/bhutane gas (sold as spray cans e.g. by Tetenal): very effective. My choice. Flammable gases, pay attention.
"Accordeon" bottles: Not very easy to clean. Not all very gas-impermeable.
Marbles: work fine but your flask is going to become very heavy.
Squeezing soda bottles: works well if the bottles are made of gas-tight plastic material.
Some people uses glass containers, other (most) use plastic containers. Plastic doesn't break easily but does not clean as easily as glass and, importantly, plastic can be gas-permeable so you must watch which plastic you use.
Plastic n.1 (PET, PETE) is the best for the conservation of development.
Plastic n.3 (PVC) is acceptable for conservation of development, but n.1 is better.
Plastic n.2 (HDPE, PE-HD) and n.4 (LDPE, PE-LD) are slightly permeable to gas, their are unfit for the conservation of developments, are acceptable for the other baths.
Mind that the cap of the container is of the same plastic of the flask. You don't want to put developer in a PET container with a HDPE cap. Use a PET cap.
I think a better way of keeping chemicals long term is with a little chemistry. If you buy the chemicals that absorb oxygen as liquids in powder form, it's easier to keep them, then cook up small batches of chemistry, rather then concentrates.
Originally Posted by BMbikerider
E-6 first developer does deteriotate. I have a gallon of the stuff expired 07 gifted to me 08. I now, though trial and error, mix it at 110%of spec concentrate, to process with good results at spec time and temp.
The RB concentrate seems to last. When it poops out on me, I resort to optical reexposure, or use a tiny some of my store of the exotic sodium borohydride to chemically reverse.
Colour Developer- the part with the developing agent I store in small glass bottles in the coor dark of my basement darkroom. They seem to last a few years past expiry if packed if the developing agent is put in glass when still fresh.
Fix concentrate can sulfate out. Other fixes will work, if pH is trimmed to the e-6 spec.
I keep my working solutions from the 1L kit inside clear PET bottles (the type you store cocktails in) that can be easily squeezed to expel all air. 1.5 months on and the chems are still working well.
I've had mine last over 4 months, after they were "exhausted" by squeezing the air out of the bottle and capping them. Room temp.
Then again those were Color chemicals, I've never used Colour chemistry before... :whistling:
It used to be you could find dedicated product in cans, similar to the canned air, but for the express purpose of evacuating air and replacing with an inert gas. Unfortunately I haven't been able to find any of this. However, Nitrogen should work as well and is available from any medical or welding gas supplier. You'll need to buy or rent a small refillable high pressure tank. Might be overkill but if you use quickly oxidizing chemicals it might be worth it.
The old canned air products you recall were halogens. Hello ozone hole over antarctica, get bigger now. That's why you don't find them any more.
Ah! That would explain it. Having just reviewed a periodic table Nitrogen is probably not a good choice for a "blanket," being as Nitrogen is lighter than Oxygen. It seems Argon is a common gas used where a non-oxygen environment is required. Couple that with a brown glass bottle and a lid that actually seals the opening and your oxidation problem should be minimal.
Originally Posted by Mike Wilde
I think also common today are propane or butane, both are heavier then air, not sure whether either gas could separate or contaminate chemistry. Obviously you wouldn't want to smoke around them, but you shouldn't be smoking anyway, especially in the darkroom.... :D
Originally Posted by scheimfluger_77