Use of inert gases
Hi all, does anyone know how carbon dioxide reacts, if at all, when used to displace oxygen from B&w chemistry in storage bottles? I used to use nitrogen years ago for colour chemistry but was wondering about co2 as I think it’s cheaper. Or does anyone recommend some other inert gas for this use? Thanks
Won’t it make the solution more acidic?
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
yes... and fizzy
I would use nitrogen. CO2 still has oxygen (O2) so I would not use it. Nitrogen will displace oxygen out of the bottle.
Protectan would be a other option..according to the MSDS https://www.digitaltruth.com/product...ectan-MSDS.pdf it´s a mixture of butane, propane and isobutane.
Other sources (Flickr) says that there is argon in it, too.
I think you can use gas cartridges like https://en.wikipedia.org/wiki/Campingaz with butane/propane mixture as replacement, which is more advantageous than carbon dioxide, because it can react with some hydroxides in the solution to carbonates (it´s not chemically inert).
Bj68
A preserving has two characteristics. First it has to be chemically inert when in contact with darkroom chem, second it has to sport a high density.Originally Posted by Dean Wilmot
The high density allows to form a gas layer on the liquid that separates the potentially remaining air from the liquid, this is important.
So you may use a can of dry air, that to blow computers, or you may get Protectan (Tetenal) that if IIRC is a mix of Butane (heavy, flamable) .
CO2 is not completely inert...
Last edited by Pere Casals; 21-May-2019 at 06:32.
Lighter gas (the kind you use for cigarette lighters) is a good substitute for protectan. It meets the criteria outlined above by Pere.
Argon is nice as well but lighter gas is easier to get generally.
CO2 works as well but is less heavy. Oxygen and acidity of CO2 are not really an issue; CO2 doesn't just fall apart into oxygen and C2, and darkroom chemicals will only absorb a small amount of CO2 under normal pressure not adding significantly to acidity.
CO2 dissolves in water and reacts with solutions with pH higher than 7.
Use lighter gas. Just don't smoke filling the bottles
Enviado desde mi SM-G935F mediante Tapatalk
I thought this might be the case. The conventional wisdom has been Nitrogen, but it is lighter than Oxygen, and won’t settle to the bottom. Wouldn’t any Noble gas further down (the periodic table) displace the Oxygen at the fluid level?
--- Steve from Missouri ---
N2 and O2 have similar density and mix very well, butane settles in the low areas, more than C02, see densities.
You have two cheap/available noble gasses: He and Ar.
Ar is abundant in the air and resulting from liquid air destilation, He is cheaper than Ar in the USA because of extraction from natural gas, but has very light density. I'm in the EU and I purchase several big 300Bar Ar bottles per year for metal TIG welding, in the USA they use more He, I was told.
Butane alone is perfect for preserving chem, also it is a liquid inside the can, but is very flamable and I guess it should not be shipped by air...
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