Gas for chemistry preservation

Exposing the equivalent of a dozen rolls of 35mm a month using gallon mixes of powdered chemistry and printing and proofing a decent portion of those frames you should have a work-flow that will not be bothered with this issues.

I just threw out $100 worth of paper that had sat for 7 years that is not useful (Brilliant FB VC). I thought it would only suffer from fog, but it prints very flat even with #5 filter and hopped up developer. I ended up buying some Ilford FB VC to see if my negatives were that off, and found it was the damn paper... I really didn't think 7 years was too long for paper in an air-conditioned environment.

Instead of messing with gas, how about using lots of little bottles for one shot per bottle storage? I mix 1 gallon or 5 liter (D-76/XTOL/DEKTOL), store half of it in 1/2 gallon bottle and divide the rest into many 250cc bottles filled to the rim. That makes it a convenient one bottle per film/tray setup. (I do not replenish) Once all the little ones are empty, I decant the other half.

I purchased these clear hard plastic bottles (my darkroom is always dark - brown bottles not necessary) for about a dollar each at Amazon.com. I have been doing this for about a year now and every chemical lasted at least 6 months and usually longer so far. This method exposes mixed chemical to air at most twice (very briefly to decant) before gets used. On top of that, convenience of pre-measured developer is great.

You can do whatever you want for the bottles and opinions vary, but these clear hard plastic bottles work just fine for me.

tkamiya said:

Instead of messing with gas, how about using lots of little bottles for one shot per bottle storage? I mix 1 gallon or 5 liter (D-76/XTOL/DEKTOL), store half of it in 1/2 gallon bottle and divide the rest into many 250cc bottles filled to the rim. That makes it a convenient one bottle per film/tray setup. (I do not replenish) Once all the little ones are empty, I decant the other half.

I purchased these clear hard plastic bottles (my darkroom is always dark - brown bottles not necessary) for about a dollar each at Amazon.com. I have been doing this for about a year now and every chemical lasted at least 6 months and usually longer so far. This method exposes mixed chemical to air at most twice (very briefly to decant) before gets used. On top of that, convenience of pre-measured developer is great.

You can do whatever you want for the bottles and opinions vary, but these clear hard plastic bottles work just fine for me.

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Good idea

Even though a protective barrier it is not, I deem very likely that most of the propane/butane mixture will be in any moment near the chemicals and most of the residual air in the upper part of the flask.

I say this because, as widely known, cars equipped with a GPL tank (mixture of propane/butane) cannot park in basements where there is not air circulation. That's because, in absence of slight air currents, GPL will tend to sit near the floor, "concentrate" there and become extremely dangerous.

Some ten years ago in Rome an awful accident happened. Some persons had signalled a gas leakage in a certain place. Technicians arrived and found that the gas leakage was from the tenement's garage. Until the day before, the "stinking substance" which was added to methane was different from the one which was added to GPL. To me they would just stink of "gas" but an experienced nose would tell the difference instantly. All technicians recognised the stink as "methane" and did not take the safety precautions that would have been necessary with GPL. Sadly, on that day a pre-programmed shift happened and the same substance was employed both for methane and GPL, the one which was previously used only for methane. Unbelievably, the gas technicians hadn't been reminded of the switch which would have occurred that day (they had been informed months in advance that that day the switch would have happened, but in certain cases a reminder is useful).

A huge explosion ensued which, IIRC, deeply damaged the 8-floor building. All the technicians died, and probably some other persons.

Every garage is not really "sealed" as you can guess, but gas did accumulate on the floor.

The lesson I gather from this is that Protectan will accumulate to the bottom of the flask unless you do something to displace it.

The Great Canyon analogy does not stick as there are winds and there is no lid. By the same token parking a GPL car in the open air is safe also in case of leakage.

That's not to say that you can put just a "puff" of Protectan and it will lay on the chemicals as if it was oil. That's to say that I don't bother too much if some air remains in the flask. I spray for 2 or 3 seconds and close the lid. No doubt some air will be trapped inside, but that shouldn't be a problem as most of the time most of the substance in contact with the chemicals will be GPL.

EDIT: substitute LPG for GPL and all will be clearer

Bob-D659 said:

Leigh B, "lighter gas" was referring to a fuel for a lighter, not a lighter than air gas.

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Yes, I understand the original intent.

But both "lighter gasses", propane and butane, are lighter than air, hence my comment.

- Leigh

Leigh B said:

Any "light" gas will be instantly displaced by air, and accomplish nothing.

For the desired preservation you need a gas that's heavier than air, so it will displace the air in the bottle, above the chemistry.

Somebody used to sell pure nitrogen for this purpose. It has all of the requisite characteristics, including being chemically inert so it doesn't degrade the chemistry.

I've looked for it recently but have been unable to find it.

- Leigh

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I believe you can get pure compressed nitrogen from a welding supplier. some local place had a relatively affordable tank of gas, regulator, hose, and trigger nozzle and small carrier. they advertised it for storing sensitive chamicals, leak detection in sensitive materials (like a hose that may carry LOX) and other uses.

but any inert gas would work. nitrogen, neon, krypton, etx would be fine.
any gas that is heavier than air would be best, it will displace the air in the bottle. any lighter than air gas will simply foat away, and leave you with the oxygen still in the bottle.

Leigh B said:

But both "lighter gasses", propane and butane, are lighter than air, hence my comment.

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They aren't, both propane and butane are heavier than air, that's why they can pose dangers in basements.