carbon dioxide and film chemistry

Discussion in 'Black and White' started by bruce_erickson|1, Aug 9, 2014.

  1. I am going to get a can of wine preservative gas: Its a canister with a N_2, argon, C0_2 mixture. One sprays it into the bottle and re-cork. The gas is heavier than oxygen and so pushes the O2 away from the surface of the wine. It seems to me this would also work quite well to preserve film development chemicals, especially color developer. I often have bottles about half-filled with chems and I know the oxygen in the air is harmful. If I spray the preservative gas into the bottle and but the cap on, then the nitrogen/argon/carbon-dioxide will push the oxygen away -- all that seems correct. The question I have is abut the C02: It will go into solution to some extent. Will it react in some negative way with the developer, blix, fix, ets..? I'm thinking it might change the ph. Any informed opinions would be welcome. Here is the link for those of you interested in getting this stuff:
  2. It will lower the pH. Instead of gas displacement decant your developer into small glass bottles. As developer is used add
    glass marbles to keep level up and air out.
  3. I use propane or glass marbles.
  4. I also use a small propane cylinder with a clear plastic hose attached to the burner and SLOWLY add the gas to the amber glass boston rounds that I use. Get your chemicals out of the plastic containers.
    One of the RV propane gas detectors mounted at floor level will be added to the darkroom in the near future. Cheap insurance.
  5. I use small cans as I have a friend named Hank Hill. :D
  6. You guys have talked me out of my plan -- now I like the marbles idea and no thanks to propane gas. How does lowering pH affect the developer or the fixer?
  7. The pH change will be pretty small, but once it goes into solution, the pressure is reduced, and air will tend to be sucked in. If you seal the bottle with seals that tighten as the pressure decreases, then you should be fine.
    The solutions where pH is important will have enough buffer to stand a little CO2.
  8. Fixer pretty much stays it's self with or without oxygen or Co2. Developer is where you need to avoid O2 for most even those that are Glycol based. But not so much.
  9. I am going to get a can of wine preservative gas: Its a canister with a N_2, argon, C0_2 mixture. One sprays it into the bottle and re-cork.

    Don't. Not a good idea, you'll introduce carbonic acid to the mix, altering the pH. But you're heading in the right direction more or less. Instead of trying to displace the oxygen, just pull a vacuum. Get down to your local wine store and get a Vacu-vin wine saver system. Works a treat with XTOL.
  10. I've heard that the wine vacuum do-dads don't produce enought of a vacuum to be effective.
    Bruce, have you tried it with chems other than XTOL?
  11. The pH change even from atmospheric CO2 can happen overnight. Many a time I've left out a flask of properly titrated acid of unknown strength. The solution was very pale pink from the phenolphthalein indicator. Overnight the pink has gone away (meaning solution is more acidic). Or if one of my students goes too far past end point so solution is bright pink it lightens as atmospheric CO2 produces carbonic acid. I would think the wine preservative would have even more CO2 and thus an even greater effect.
  12. CO2, like other gases, is 0.04 moles/liter. If there is a small air space above the liquid, and it is reasonably buffered, the pH change will be small.
    Most developers are close to 1M carbonate and/or sulfite.
    But if the bottle is half full, or even less, then it might be enough to notice.
    But I have always used marbles, most often in plastic bottles that you can't squeeze quite enough.
  13. Guys, stop and put this into perspective for a minute. A gallon of developer is maybe $10, and fixer is about the same. It simply isn't worth the time or trouble, let alone buying a bottle of any kind of preservative. And propane? Wait til the insurance company hears that once after your house burns down. :)
  14. Is a small cylinder of propane carefully used inherently more dangerous in a darkroom than natural gas is to a house that uses it for heating, cooking, heating water, or for drying clothes? Frankly, I think not.
    Perhaps more so than electrical wiring may be, but even wiring can cause quite a commotion under some circumstances.
    I think judicious use of "stuff" may mitigate somewhat it's inherent dangers.
  15. Butane is heavier than propane, and you could just point a disposable lighter in. The amount should be small enough not to cause a problem.
    When you get to pounds (kg) of either, you have to be a little more careful. Both are heavier than air and sink to low spots, possibly near pilot lights. (Seems to be common for people soaking marijuana in it.)
    Natural gas is lighter than air, so tends to be less of a problem.
  16. If you fear propane then use butane. ... I get both in small bottles. Butane I can get at a $ store.
  17. Glen that is for extracting oil but then that is not why I use it but as an Alchemist I know these things.
  18. Larry, how do you use the butane? It seems like I recall seeing some small butane cylinders using in silver soldering, but I don't recall the you attach a flexible hose?
  19. Yes A flexible hose.
  20. Cute Lex. :)

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