Darkroom - prevent oxidation in chemistry

[tezzasmall]

CO2 is heavier than air...you could blow that into the bottle before capping it. CO2 is cheaply available for making sparkling water!

+1.

I hold my breath and exhale into my amber glass bottles before capping. Been doing it for years.

This subject has been debated many times, both on this forum and my other main site, FADU.

I bought some small CO2 canisters for my wine making and asked about using them, to be told that although CO2 is heavier than air, it will be absorbed into solution, so not giving any protection.

Various gases were suggested including argon, but that is expensive to buy in smaller aerosols. One could buy much larger amounts of it in very bulky and heavy canisters from builders supplies, but this would also require a dedicated release valve and piping.

Bad to useless were the comments for the plastic concertina bottles and pop bottles. Both leak air through them, and were considered at best OK for short term storage.

The main item agreed upon is cigarette lighter gas - butane, which is both very cheap and easily available. I buy mine for £1 a tin at the Pound Shop. And yes, care has to be taken, as with anything, but there have been no horror stories. It then can be used in tested chemical bottles or glass bottles and most importantly, in tanks like my Nova slot processor, where a short squirt does the job!

Terry S
UK

 

[Doremus Scudder]

No news from the OP for a while.

If they are using large tanks, then acquiring some floating lids seems wise.

If they are trying to keep chemicals in a tray from oxidizing between sessions, covering the developer tray with Saran Wrap (not other brands - they are more gas permeable) works overnight. So does pouring the developer back into a bottle.

Accordion bottles are a pain to clean, subject to sudden failure due to pleats breaking and highly gas-permeable. Three strikes in my book.

Glass bottles are the ticket for storing liquid solutions if possible. Lots of plastic bottles are gas permeable. I've had solutions go bad in bottles from chemical suppliers like Photographers' Formulary when the same solution stored in a glass bottle lasted much, much longer. One batch of ID-62 stock I mixed recently went bad in a plastic bottle in a week or so. The glass-stored half is still clear after months. PET drink bottles are better than a lot of bottles sold specifically for photo chems.

Mixing one batch or one session is the best way to go if you can manage it.

Best,

Doremus

 

[Brad Deputy]

I've had great luck using canned air (Difluroethane, HFC-152a) available cheaply from Costco in 6 packs. Heavier than CO2 or butane.

I spray gently into the bottles with the lid on with a slight gap for the nozzle until the pitch stops decreasing, then close it up.

I've kept all my developers including C41 and fix up to a year easily in those black plastic eTone bottles. I'd like to use glass but haven't found a source or ones with good seals on them yet.

 

[Petrochemist]

I've had great luck using canned air (Difluroethane, HFC-152a) available cheaply from Costco in 6 packs. Heavier than CO2 or butane.

I spray gently into the bottles with the lid on with a slight gap for the nozzle until the pitch stops decreasing, then close it up.

I've kept all my developers including C41 and fix up to a year easily in those black plastic eTone bottles. I'd like to use glass but haven't found a source or ones with good seals on them yet.

Fluorocarbons are quite severe ozone depleting materials (not quite as bad as CFCs but still bad) wouldn't it be better just to add marbles to the glass bottle to bring the liquid to the top?

 

[MattKing]

Fluorocarbons are quite severe ozone depleting materials (not quite as bad as CFCs but still bad) wouldn't it be better just to add marbles to the glass bottle to bring the liquid to the top?

A glass bottle half filled with marbles and half filled with developer is a pain to use, heavy, and vulnerable to breakage.
In addition, it is difficult to tell how much developer is left in such a container.
The marbles are a bit of a pain to clean as well.
Using several smaller bottles with narrow necks is a lot more practical.

 

[chuckroast]

No news from the OP for a while.

If they are using large tanks, then acquiring some floating lids seems wise.

If they are trying to keep chemicals in a tray from oxidizing between sessions, covering the developer tray with Saran Wrap (not other brands - they are more gas permeable) works overnight. So does pouring the developer back into a bottle.

Accordion bottles are a pain to clean, subject to sudden failure due to pleats breaking and highly gas-permeable. Three strikes in my book.

Glass bottles are the ticket for storing liquid solutions if possible. Lots of plastic bottles are gas permeable. I've had solutions go bad in bottles from chemical suppliers like Photographers' Formulary when the same solution stored in a glass bottle lasted much, much longer. One batch of ID-62 stock I mixed recently went bad in a plastic bottle in a week or so. The glass-stored half is still clear after months. PET drink bottles are better than a lot of bottles sold specifically for photo chems.

Mixing one batch or one session is the best way to go if you can manage it.

Best,

Doremus

I agree, at least for the monochrome developers I use. Stock is mixed and then split into multiple smaller glass bottles for long term storage, with a single bottle being depleted for day-to-day use.

For paper developer, I have been moving to what is essentially Ansco 130 which has a very long life and low oxidation tendency.

For film, I've been using PMK Pyro, stored in glass bottles, or Pyrocat-HDC with Part A mixed with glycol. Again, both demonstrate very, very long shelf lives.

I avoid pretty much all generic plastic storage containers because they are gas permeable. There are some that are not, but I find glass to be widely available and consistent in use.

 

[mshchem]

Fluorocarbons are quite severe ozone depleting materials (not quite as bad as CFCs but still bad) wouldn't it be better just to add marbles to the glass bottle to bring the liquid to the top?

No ozone depletion potential. However HFCs are strong global warming gases. 153a is 100+ times that of CO2. Not sure how much longer this will be allowed. It would work well for displacing air in a bottle.

 

[Photoemulator]

I like the StopLossBags. And I wonder how many took the empty wine bags comment to heart?

 

[DREW WILEY]

Floating beads have been used in industrial sized containers. But unless one is dealing with large volumes themselves, I don't see much practicality for that in a home darkroom. But these sure beat sunken marbles.

 

[Petrochemist]

A glass bottle half filled with marbles and half filled with developer is a pain to use, heavy, and vulnerable to breakage.
In addition, it is difficult to tell how much developer is left in such a container.
The marbles are a bit of a pain to clean as well.
Using several smaller bottles with narrow necks is a lot more practical.

I guess weight would be an issue with a 2.5l winchester, I never had an issue with 250ml bottles. My usage must be less than yours

Pouring the marbles out into a developing tray & flushing with copious water has always seemed to do the trick of cleaning them without much effort.

 

[Raghu Kuvempunagar]

I like the StopLossBags. And I wonder how many took the empty wine bags comment to heart?

Similar to wine bags, I have stored developers in 1 l liquid soap pouches (Savlon) and they work fine.

 

[alanrockwood]

CO2 is heavier than air...you could blow that into the bottle before capping it. CO2 is cheaply available for making sparkling water!

A potential problem with blowing CO2 into a bottle containing a water based solution is that CO2 will likely shift the pH of the solution.

CO2 is part of the carbonic acid/bicarbonate/carbonate system. If the solution is basic (as are most developer solutions) adding CO2 will tend to lower the pH, thus throwing the chemistry off from what it is supposed to be.

 

[Don_ih]

CO2 is part of the carbonic acid/bicarbonate/carbonate system. If the solution is basic (as are most developer solutions) adding CO2 will tend to lower the pH, thus throwing the chemistry off from what it is supposed to be

You should add "by an infinitesimal amount." It's just a tiny volume of gaseous CO2. At 0.001836 grams per cubic cm, that's not a lot of mass.

 

[koraks]

You should add "by an infinitesimal amount." It's just a tiny volume of gaseous CO2. At 0.001836 grams per cubic cm, that's not a lot of mass.

That's correct. The absorption of aerial CO2 in stuff like developers is a total non-issue. It pops up from time to time, but has no practical relevance whatsoever.

 

[BobUK]

Fluorocarbons are quite severe ozone depleting materials (not quite as bad as CFCs but still bad) wouldn't it be better just to add marbles to the glass bottle to bring the liquid to the top?

For some reason glass marbles are no longer cheap in the UK.
Also a pain when pouring out the solution from the bottle to the measuring cylinder. They all seem to want to escape.
I once cracked a glass measuring cylinder when a couple dropped from the bottle.
Stick with the gas lighter fuel. Cheap and reliable.
No more dangerous than refilling a gas cigarette lighter.

 

[c41]

+1.

I hold my breath and exhale into my amber glass bottles before capping. Been doing it for years.

I'm not sure if these breathe out the CO2 posts are a joke that's gone over my head? but fwiw we obviously only breathe out a little bit more CO2 than we breathe in, like 3-4% or something. Maybe try farting into the bottles, get some methane in there?

 

[Petrochemist]

For some reason glass marbles are no longer cheap in the UK.
Also a pain when pouring out the solution from the bottle to the measuring cylinder. They all seem to want to escape.
I once cracked a glass measuring cylinder when a couple dropped from the bottle.
Stick with the gas lighter fuel. Cheap and reliable.
No more dangerous than refilling a gas cigarette lighter.

Perhaps they've gone out of fashion. I have a big bag of them around from decades ago, so have no need to buy them.

Meanwhile I'll be keeping my eye's open for some nice boxed wine. I do see a certain appeal to that solution

 

[Truzi]

I'm not sure if these breathe out the CO2 posts are a joke that's gone over my head? but fwiw we obviously only breathe out a little bit more CO2 than we breathe in, like 3-4% or something. Maybe try farting into the bottles, get some methane in there?

But then you add a fire hazard

 

[Patrick Robert James]

Glass bottles with Butane. I use the smallest squirt of Butane. I've had paper developers last years. My one exception to glass is I keep my mixed fix in an Arizona Ice Tea gallon sized jug which is very thick plastic.

 

[quigs]

I divided my 1L Ilford DD-X up into 100ml amber glass bottles and capped them off with nearly no air gap. It's still going strong 9 months later. Given the price of DD-X I don't intend to test the limits, but I have already exceeded the 6-month-open threshold that it supposedly stops working after when exposed to air (which it hasn't).