Use of inert gases

[Dean Wilmot]

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

[Peter De Smidt]

Won’t it make the solution more acidic?

[consummate_fritterer]

yes... and fizzy :)

[Steven Ruttenberg]

I would use nitrogen. CO2 still has oxygen (O2) so I would not use it. Nitrogen will displace oxygen out of the bottle.

[BJ68]

Protectan would be a other option..according to the MSDS https://www.digitaltruth.com/products/tetenal_msds/protectan-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

[Pere Casals]

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

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.

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...

[koraks]

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.

[EdoNork]

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

[scheinfluger_77]

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.

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) and Argon (inert, not flamable).

CO2 is not completely inert and is not heavy enough, but perhaps is better than nothing.

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?

[Pere Casals]

The conventional wisdom has been Nitrogen, but it is lighter than Oxygen, and won’t settle to the bottom.

N2 and O2 have similar density and mix very well, butane settles in the low areas, more than C02, see densities.



Wouldn’t any Noble gas further down (the periodic table) displace the Oxygen at the fluid level?

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...

[nmp]

- CO2 has some solubility in water, so the solution will absorb it to form carbonic acid reducing the pH.

- different gases have different densities, but it does not mean they separate as they are miscible in each other.

- If N2 is used, simply force it into the bottle at higher pressure which will displace the air, put the cap on and as long as it is airtight it will keep.


Instead, why not use something like this:


https://www.amazon.com/Kaiser-204198-500-1000ml-Accordion-Bottle/dp/B000L9MWDS

[Ulophot]

Many years ago, I read that holding one's breath for a good forty seconds or so decreased the ratio of oxygen in the lungs, so that exhaling into the developer container would help preserve the chemical. I have used this free source, having once used nitrogen sold for preserving wine, which simply cost too much at the time. I just looked up this phenomenon, after read this thread, since I couldn;t recall whether it was carbon dioxide or nitrogen which increased significantly in proportion. A long explanation written by a specialist contains a graph showing nitrogen plummeting as breath is held, so it must be the carbon dioxide that increases.

[Gary Beasley]

If you have the room and a tank and regulator nitrogen is pretty cheap at the airgas stores where you get welding gases. I paid $18 for a refill last time. Not sure what the argon would be but it shouldnt be outrageous.

[EdSawyer]

Argon is more than Nitrogen. I still have some stuff Beseler used to sell in an aerosol can, probably outlawed now, but it works well.

[Jim Noel]

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

CO2 is NOT an inert gas.

[Drew Wiley]

Argon is commonly used. But that ordinary comes in big pressurized cylinders from welding suppliers. Wine-making supply shops sell smaller volumes, as well as some woodworking stores and on-line sources to keep varnishes fresh by displacing air. A totally different kind of trick involves ceramic micro-beads which float atop solutions to slow down oxidation; they're available from laboratory supply houses. My own answer is simply not to keep developers long enough for oxidation to have
an effect; and I never, ever re-use or replenish them.

[Joe O'Hara]

I would not use butane for this purpose. Actually I would not use it for any purpose indoors,
except under a fume hood, if I had one. It is crazy flammable.

CO2 will react with water to form some amount of carbonic acid. This is the acid in "acid rain" and
what eats the ancient marble statues standing outside. The sulfite or carbonate in developers will
scrub that but it's not helping the situation.

Argon or nitrogen are better choices. Or, you could just mix smaller quantities of developer or store it
in smaller bottles. Or, "canned air", usually some kind of flourocarbon mixture, but they usually (in the US
at least) contain "bittering agents" to discourage inhalation abuse, and who knows what they are.

I just mix enough to use it up in a month or so and don't lose any sleep over it.

[Joe O'Hara]

Clarification: Carbonic acid is not the only acid in "acid rain". Sulfuric acid (mostly from burning
coal, but also from volcanoes) is a bigger issue, but carbonic acid was dissolving marble and
other exposed rocks for quite a while before coal was mined.

[Eric Woodbury]

It's the CO2 in the atmosphere that is increasing the oceans acidity and dissolving the reefs.

I used N2 for many years with PMK in a drum (not the method in the book). I had a short tank in the darkroom. Works fine and is inert at normal temps. No reason to bother with Argon.

[Drew Wiley]

Accordion bottles were mentioned. These were once routinely available at camera stores. But they're still so poorly made with permeable thin plastic that I doubt that they were ever a serious answer. I prefer to decanter or split up developer volume into multiple small amber glass bottles, filled to the top. As for rotary processing, there are pyro tweaks much more resistant to aerial oxidation than PMK. But a related problem is how certain rotary drives (esp Jobo) run at unrealistically high RPM's, even at the lowest setting. I'd rather just roll the drum gently back and forth along the bed of the darkroom sink if I still did PMK rotary. I also have big custom drum machines with far more cooperative RPM's for color processing, which would be suitable for pyro.

[Drew Wiley]

Carbonic acid - I was retouching a print today of a dawn shot of a marble cliff in Kings Canyon, taken two weeks ago, where over 240 caves have now been identified. Most of this acid comes from decaying vegetation. The problem with the acidification in the oceans, due mostly to atmospheric CO2, is that it has the potential for super-additive increase. Those very microorganisms, corals, and mollusks which effectively trap carbon to create shells or exoskeletons, and over time have created limestone, are now having a very difficult time forming their calcareous shells or branches due to oceanic pH shift. It's gotten so bad that many of our West Coast oyster farms have had to import the early stage of their oysters, or raise them in controlled pH tanks until their tiny thin shells are thick enough to resist the acidic corrosion. Back when my wife and I were taking our honeymoon, we traveled to Kauai in a airline 3-seater next to a lady who was a Coca Cola executive. My wife asked her if she got her Coke for free. She responded that she never drank the stuff because every ingredient is shipped in Hazmat tank cars, esp the concentrated carbonic acid. Everybody knows what carbonized drinks do to teeth !

[jim10219]

I use old 2 liter soda bottles. I squeeze all of the air out of them and tighten the cap down when the liquid reaches the top. I generally replace them every time I mix up new chemistry, so I don’t have issues with them leaking air or liquid. Since I already have them on hand, they only cost me the time it takes to wash them out. I even use different shaped bottles (Coke, Dr. Pepper, Sprite, etc.)for different chemicals, which proved handy once when I accidentally poured out a tray of fixer, thinking it was the wash tray in the dark. It was easy to refill with the right chemical without turning on the lights. I’ve had D76 last 8 months in those bottles. It may even last longer, I haven’t had the opportunity to test it.

[Drew Wiley]

Yeah, soda bottles are now made of better plastic than so-called darkroom bottles (though you can get serious plastics from actual lab supply companies). Of course, the trade-off is that all those new soda and water bottles take forever to decompose.

[BJ68]

I use old 2 liter soda bottles.

Be careful....if the solution contains Sodium or Potassium hydroxide (1 to 10%) you can get problems, if the bottle is made of PET see "Polyethylene Terephthalate (PET)--Chemical Compatibility" https://roboworld.com/wp-content/uploads/2017/08/PET_ChemicalCompatibility.pdf
So far I have seen most e.g. developer solutions are made without NaOH or KOH but a few have it: For example Part B of "Pyrocatechin Compensating Formula" or "AGFA Rodinal - Original Version" with 20% concentration see http://www.danieldevinephotography.com/?p=4317

Bj68

[koraks]

I can tell from first-hand experience that ldpe bottles (eg used for soft drinks) will be dissolved by Fuji RA4 developer. HDPE will work fine though.

As to the Coca cola: as far as I know the acid is added in the firm of phosphoric acid. It's a great rust cleaner. Carbonic acid has a pka of only 6.36 and therefore is by far not acidic enough to give coca cola its acidity, nor is it likely to interfere very badly with the pH of a developer.

[Pere Casals]

Be careful....if the solution contains Sodium or Potassium hydroxide (1 to 10%) you can get problems, if the bottle is made of PET see "Polyethylene Terephthalate (PET)--Chemical Compatibility" https://roboworld.com/wp-content/uploads/2017/08/PET_ChemicalCompatibility.pdf[/url]
Bj68

This theory is not directly applicable to BW darkroom regular chem, because the caustic agent is not alone, forming a tampon.

An easy example: a PET bottle with Sodium hydroxide can also contain a certain acid to form a salt, say sea water.

So a RA-4 developer may disolve PET (Koraks), while high content of Sodium hydroxide in the formula may not determine that.



I can tell from first-hand experience that ldpe bottles (eg used for soft drinks) will be dissolved by Fuji RA4 developer. HDPE will work fine though.

As to the Coca cola: as far as I know the acid is added in the firm of phosphoric acid. It's a great rust cleaner. Carbonic acid has a pka of only 6.36 and therefore is by far not acidic enough to give coca cola its acidity, nor is it likely to interfere very badly with the pH of a developer.

Xtol preserves very well inside soda bottles.


_________________________________________-

Please, if using food containers to store chem please label it very well (and permanent) with skull and bones, and keep out of the reach for other people, later wash and destroy the container, for disposal.

[Drew Wiley]

The skull and bones symbol probably belongs on two thirds of what people drink from those bottles to begin with!

[Pere Casals]

The skull and bones symbol probably belongs on two thirds of what people drink from those bottles to begin with!
Sure! :)

[Jac@stafford.net]

Several years ago I bought a large tank, with spout, said purpose was specifically for storing water. Then over a couple month's I deposited water from my home distiller until it was full. Circumstances caused me to leave film process for about 18 months, and when I finally went to the tank it was empty!

Oh, I keep the room under 50% humidity, with the atmospheric water draining into the city system.

Something to think about.

[Peter De Smidt]

What about duster products, such as Dust-off and similar? Most seem to have 1,1-Difluoroethane.

[Bob Salomon]

What about duster products, such as Dust-off and similar? Most seem to have 1,1-Difluoroethane.

And, by law in the USA,a bitterant to discourage inhaling the stuff to get high!

[Jac@stafford.net]

Thinking of economy: are farts inert?

[Drew Wiley]

Bob, if people didn't get high on aerosol cans, "street art" wouldn't even exist. But what I can't figure out is whether the graffiti is due to their brains already being rotted out, or if it is necessary to destroy brain cells afterwards in order to appreciate that kind of thing as art. I simply call it vandalism.

[Bob Salomon]

Bob, if people didn't get high on aerosol cans, "street art" wouldn't even exist. But what I can't figure out is whether the graffiti is due to their brains already being rotted out, or if it is necessary to destroy brain cells afterwards in order to appreciate that kind of thing as art. I simply call it vandalism.

Drew, they added the bitterant because people, mostly kids, were dying from inhaling the canned air. Since they are also classified as a hazmat they should just be banned!

[Drew Wiley]

It always amazes me how people of offices will spend hundreds of dollars a year on canned air but can't afford a modest air compressor. Kids inhale all kinds of aerosols, sometimes with permanent health effects, including behavioral and mental illness. What I especially dislike,however,is glamorizing graffiti when it inherently involves careless use of unhealthy products. But the same categories of hazardous solvents can come from non-pressurized cans and bottles, the number one source not being spray paint at all, but nail polish!

[Jim Jones]

Drew, they added the bitterant because people, mostly kids, were dying from inhaling the canned air. Since they are also classified as a hazmat they should just be banned!

Not only might they die, but a kid in my area is awaiting his murder trial for passing out after sniffing cleaner, and crashing into another car at 85mph, killing the driver.

[J_3]

Ar isn't very hard to come by. It's used as the inert gas in TIG welding. You can weld magnesium alloy with an argon gas shield to give you an idea how inert it is. Nitrogen is 'inert enough' for most applications not involving heat or pressure and is cheaper.

[Eric Woodbury]

Jac@stafford

No. Methane. CH4. A highly reactive hydrocarbon. Tetrahedral. No open flames, please.

[Jac@stafford.net]

It always amazes me how people of offices will spend hundreds of dollars a year on canned air but can't afford a modest air compressor.

Excellent point! Can you point us to a small, quality compressor with moisture filter? Thank you.

[chassis]

Storage options as I see them, in order of lower oxygen permeability (good for photochemical storage) to higher oxygen permeability (not as good for photochemical storage):

- glass bottle
- "wine bag", with an EVOH layer
- PET bottles, e.g. soft drink bottles

A benefit of the "wine bag" and PET bottle options, is the ability to squeeze out residual air before closing. Glass bottles do not provide this option, unless a displacement medium, such as marbles is used. The use of a displacement medium is inconvenient in my experience.

Comments have been made that E6 developers are more strongly caustic than others, and that PET may not behave well with these solutions. I have no experience with this. I have successful experience storing B&W and C-41 chemicals in PET containers.

I do not include in the list the traditional brown polyethylene (PE) storage bottles, accordion or otherwise. These were likely the easiest option available, before the widespread availability of PET bottles a few decades ago. PE is not a good performer relative to oxygen permeation.

Plastic type (PET, HDPE, LDPE, etc.) is often noted on the bottom of a container.

[Duolab123]

Be careful....if the solution contains Sodium or Potassium hydroxide (1 to 10%) you can get problems, if the bottle is made of PET see "Polyethylene Terephthalate (PET)--Chemical Compatibility" https://roboworld.com/wp-content/uploads/2017/08/PET_ChemicalCompatibility.pdf
So far I have seen most e.g. developer solutions are made without NaOH or KOH but a few have it: For example Part B of "Pyrocatechin Compensating Formula" or "AGFA Rodinal - Original Version" with 20% concentration see http://www.danieldevinephotography.com/?p=4317

Bj68

I have used PET for XTOL no problem. E6 color developer, one of the 3 part concentrate DESTROYED the PET. I found a bottle of XTOL stock solution, I had in a PET soda bottle, I had squeezed out all the air. The bottle was 11 years old, just for fun I developed a roll of 120 HP5, worked perfectly!
I guess the lesson for me, if it's dilute, squeeze out the air. I use butane when I split chemistry, in Nalgene HDPE bottles.

Don't waste valuable Helium. It is a great Noble gas though.

[Axelwik]

You'll end up with carbonated chemicals with a lower pH due to carbonic acid.