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  1. #11
    GRHazelton's Avatar
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    Quote Originally Posted by heterolysis View Post
    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?

  2. #12
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    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.

  3. #13
    AgX
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    Protectan is Butane by now.

  4. #14
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    Quote Originally Posted by GRHazelton View Post
    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.

  5. #15
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    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.


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  6. #16
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    Quote Originally Posted by ambaker View Post
    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.

    Quote Originally Posted by ambaker View Post
    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...

    Quote Originally Posted by ambaker View Post
    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.

  7. #17
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    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

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