Gas for chemistry preservation

StigHagen · May 28, 2011

I have been looking for some gas on bottle to replace oxygen in my bottles to make my chemistry last longer. What do you use? Im going for brown bottles but still looking for a cheap and easy accesible gas on bottle solution that does the job.

Came across this product:
http://www.wineenthusiast.com/wine-...ne-preservation-spray.asp?AfID=CJ&PID=2852851

jm94 · May 28, 2011

that looks okay, and also aeroduster compressed air (http://en.wikipedia.org/wiki/1,1,1,2-Tetrafluoroethane)
http://www.rapidonline.com/producti...+duster,+dust+and+dirt+remover&moduleno=61592
this one or that one will both do the job just fine

Bob-D659 · May 28, 2011

The wine preserver contains carbon dioxide, bad for developers. It combines with the water to form carbonic acid and messes up the PH of the developer.

StigHagen · May 28, 2011

jm94 said:
that looks okay, and also aeroduster compressed air (http://en.wikipedia.org/wiki/1,1,1,2-Tetrafluoroethane)
http://www.rapidonline.com/producti...+duster,+dust+and+dirt+remover&moduleno=61592
this one or that one will both do the job just fine

I have compressed air already, will that work? Will that remove oxygen?

StigHagen · May 28, 2011

Bob-D659 said:
The wine preserver contains carbon dioxide, bad for developers. It combines with the water to form carbonic acid and messes up the PH of the developer.

What is best for developers?

hoffy · May 28, 2011

This was talked about in length last week in the colour sub forum:
(there was a url link here which no longer exists)

Diapositivo · May 29, 2011

I use Tetenal Protectan spray, this is a specific product labelled as "antioxidant for photographic solutions". A 400ml can allows the displacement of around 100 litres of air according to the label. It's a mixture of Propane gas (20 - 40%) and n-Butane gas (> 60%). As you already guessed it is "extremely flammable".

Somebody says lighter gas (the propane or butane stuff, there also are alcohol lighters and gasoline lighters, beware) should work the same and cost less.

<OT>
And as far as wine is concerned I prefer those caps that allow you to pump air content out and make some sort of vacuum in the bottle. Preserving wine with carbon dioxide is probably justified with sparkling wine though.
</OT>

mgb74 · May 29, 2011

StigHagen said:
I have compressed air already, will that work? Will that remove oxygen?

If it's just compressed air, it will have the same oxygen content as ambient air.

Leigh B · May 29, 2011

Diapositivo said:
Somebody says lighter gas (the propane or butane stuff, there also are alcohol lighters and gasoline lighters, beware) should work the same and cost less.

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

StigHagen · May 29, 2011

How do you know when you have filled it with gas and there is no air left?

Bob-D659 · May 29, 2011

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

I use pure nitrogen, purchased from a welding supply shop. You do need a regulator to lower the pressure from 2,000 psi.

StigHagen, that depends on how empty the bottle is.I have a nozzle that meters out 100cc per second, so it doesn't take long.

An easy way to tell is push a piece of plastic film into a measuring cup,suck the air out with a straw, then stick the dispenser nozzle into the straw and see how long it tales to fill the cup.

If you flow the gas in too fast, it won't displace the air. Having the nozzle down near the surface of the liquid helps.

Diapositivo · May 29, 2011

StigHagen, I think it is not really important to displace all air left. Even if some air remains in the flask, the propane/butane mixture, which is heavier than air, will sit on the chemicals and form an insulating blanket. The air will be confined in the upper part of the flask, near the lid, and will not touch the chemicals in any case.

Anyway, the instructions on the Tetenal product say that 5 seconds of "spraying" will displace 250 ml (that's 1/4 of a litre, you do the math in any other inferior volume measuring convention ) so if you want to displace the entire content of air you have a rule of thumb for that.

Colin Corneau · May 29, 2011

Good information...nitrogen sounds the most promising. Call me a pessimist but I don't like the idea of bottles with some amount of flammable explosive gas sitting around near me.

jm94 · May 29, 2011

i don't understand why tentenal would use hydrocarbons (butane and propane) for their protectan spray if many other alternitives were there, including the refregiant gas, nitrogen, argon and the likes. apart from the fact most hydrocarbons are heavier than air.... and i too dont like the thought of having very flammable containers around, but if you look on deodorant cans, they contain a butane and propane mix! unless the hydrocarbons is a cheaper option than the other options?

Bob-D659 · May 29, 2011

Hydrocarbons like butane/propane mixes are used as they are in a liquid form at relatively low pressures at room temp and form a large amount of gas as they evaporate. Argon and nitrogen at similar pressures will have very little product in a same sized container. Butane and most refrigerants, which include propane and carbon dioxide expand to approx 250 times as they evaporate from a liquid form. So 200ml of liquid butane in a can supporting 75psi, at room temp produces a very large volume of gas, something like 50 liters. 200ml of argon or nitrogen at 75-100psi will expand enough to produce approx one to two liters of gas. If I got the math right.

archer · May 30, 2011

The most used gas to displace oxygen in CCD cameras is Argon as the molecules are heavy and very large and it is the preferred gas to protect wine and paints. Argon is relatively expensive but not prohibitively so. I use butane or propane and it works well but it is flammable unlike Argon.
Denise Libby

StigHagen · May 30, 2011

Bob-D659 said:
Hydrocarbons like butane/propane mixes are used as they are in a liquid form at relatively low pressures at room temp and form a large amount of gas as they evaporate. Argon and nitrogen at similar pressures will have very little product in a same sized container. Butane and most refrigerants, which include propane and carbon dioxide expand to approx 250 times as they evaporate from a liquid form. So 200ml of liquid butane in a can supporting 75psi, at room temp produces a very large volume of gas, something like 50 liters. 200ml of argon or nitrogen at 75-100psi will expand enough to produce approx one to two liters of gas. If I got the math right.

Then the butane option should be far cheaper and last for a long time? I guess if Im careful and using small portions butane is ok.

StigHagen · May 30, 2011

Diapositivo said:
StigHagen, I think it is not really important to displace all air left. Even if some air remains in the flask, the propane/butane mixture, which is heavier than air, will sit on the chemicals and form an insulating blanket. The air will be confined in the upper part of the flask, near the lid, and will not touch the chemicals in any case.

Good point...can anybody confirm?

hrst · May 30, 2011

This is discussed to death once a month.

(1) Do not use carbon dioxide
(2) Do not use air to displace air. This is a no-brainer......
(3) The ONLY way to REALLY displace ALL of the air is to use a closed nitrogen cabinet.
(4) Butane works quite well but a small "puff" is not enough, and it is not perfect. It does not form a very good "protective barrier" but it mixes with air at least to some extent.
(5) Usually, having a plastic bottle that can be squeezed is the most efficient and also easiest way. http://www.youtube.com/watch?v=hdu4cCOrf3I

hrst · May 30, 2011

StigHagen said:
Good point...can anybody confirm?

I can dis-confirm it based on real testing. It just does not work like that in practice.

Kirk Keyes · May 31, 2011

hrst said:
I can dis-confirm it based on real testing. It just does not work like that in practice.

It doesn't work like that because of Brownian motion and microconvection currents will cause any air in the bottle to mix with any "heavier than air" gas.

Bob-D659 · May 31, 2011

If it did work like that, Death Valley should have been full of R12, propane and all their relatives by now, instead of those gasses making their way up to the ionosphere.

hoffy · May 31, 2011

Seriously? Are we trying to fill a swimming pool with heavier air out in the open, or are we trying to put a protective barrier on the top of a sealed bottle with maybe the surface area of a few square CM's?

Kirk Keyes · May 31, 2011

A "protective barrier" is not really what happens. What we need to do is displace the oxygen from the bottle with anything that is unreactive to the chemicals in the solution. I use a cylinder of nitrogen that I bought from a welders supply house.

vpwphoto · May 31, 2011

Any welding supply place can sell you a lifetime supply of N2 gas. That is what was used in air-burst agitation machines also.

Sorry for the duplication of above post... I was replying to an earlier poster not knowing where to get N2.

Also... Just shoot more... then you won't have to worry about oxidation!!

Gas for chemistry preservation

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