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Preserving Chemicals

bvy

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I've been developing paper negatives from pinhole cameras. My chemicals are Ilford PQ Paper Developer and Ilford Rapid Fixer, both liquid concentrates.

I use the stuff regularly but not frequently, so I'm not exactly burning through the stuff. A half liter of developer, for instance, lasts me at least a year. So my question is about preserving the chemicals -- keeping them fresh. Keep the stuff in full, airtight bottles, right? Well, any ideas how to do that? For every solution I've found, I've found another reason not to do it:

Fill the bottles with marbles to keep the chemicals top level. But marbles can accumulate crud over time and contaminate the chemicals.

Buy and use collapsible bottles. But these are unreliable and often not fully airtight.

Can anyone help me with some ideas, or at least set the story straight? Thanks.
 
I use Kodak chemicals. For paper developers, I buy 1 gallon bag of Dektol. Rather than storing the whole thing in 1 gallon bottle, I have the following:

1 1/2 gallon bottle
1 1/4 gallon bottle
2 1/8 gallon bottle

When I mix a fresh batch, I fill all of them to the brim. Then start using them from smaller ones first. Once both 1/8 gallon bottles are empty, I divide 1/4 bottle into two 1/8 gallon bottles. Once all that is gone, 1/2 gallon goes into smaller 3.

This way, the largest possible amount exposed to air as result of bottle not being full is about half of the smallest bottle. It will last about 2 months in this condition. I usually use them faster than that.

For my bottles, I use plastic chemical storage bottle from Adorama. Not the accordion type, but regular brown plastic bottles.

Chemical storage is something of a religion. You'll hear lots of opinions, ideas, methods, beliefs, etc. This is what works for me.
 
I mix a gallon of developer at a time. I use 3x 1 liter glass bottles, 1 500mL bottle, and 2 250mL bottles. That way I mix up a gallon and I can always use either 250mL, 500, or 1000. But if you don't fill them you can use wine preserver (nitrogen)
 
Use the argon gas rather than the nitrogen gas preserver as it's the same price and the molecule is larger making for less leakage and as far as I know the argon is completely inert and the nitrogen may interact with some chemicals from what I've been told.
Denise Libby
 
I was given a liter pack of Dektol and it's not something I use much, either.
I mixed it up as directed and poured it into a wine cask bladder. These are multi-layered mylar with some kind of reflective layer on them. The ones I see have a rubber bung/tap at the bottom. I remove the bung (or use a funnel) and pour in the concentrate, replace the bung and with the bung uppermost expel all the air until some developer comes out. Label the bladder clearly with a marker pen and store it in the fridge.
I just took out that Dektol and after a good shake, poured a few mls into a glass, diluted about x10 and after the tiny sediment dissolved, it took a minute to blacken a tail of film. Developer still clear - no brown color.
I made that Dektol up in June 08 according to the label.
I did say I didn't use much!
I also keep a gallon of hypo the same way, since it goes 'off' if exposed to the air for long, turning into the sulfate. Lasts years this way.
None of the above is any use if you don't see/buy wine in a box.
Cheers
Murray
 
Thanks for the ideas. Nitrogen/argon sounds like a good idea. I've looked around on the internet, but I'm not getting a feel for how to use these gases. Is a "system" required? Or do you just spray the gas into the bottle and quickly cap it? Seems kind of clumsy, but I've heard of stranger things...
 
yes, spray into biottle and cap is about it.

If you are looking for a trick, spray with one hand holding the can and extension tube , and the second hand , palm down, holding the bottle on a bit of an angle.

Put the extension tube into the neck of the botlle and place it just above the liquid, and give a puff of gas for a second or two.

If the bottle is mostly full, I find doing this you can feel the cooler gas (as a result of just coming out of the spray can) flowing across the back of your hand when the botlle gassing action has dosplaced all of the existing air with the protective gas
 
A lower cost way without gas is get a bunch of small bottles and fill to the brim, then seal. I use 250ml Amber Glass Large Mouth Bottle to be able to mix up Xtol (20 bottles) or D76 (16 bottles) and store in smaller bottles with no air so it would last longer. Then I could use one shot or 1:1.

If you store in lager and smaller bottle, refilling the small bottles as they become empty, you are exposing the developer to air each time, so its better to just have enough small bottles and be done with it.

The Nitrogen is a good solution if you do more volume and can justify the cost. Argon cost more but I don't know of any advantage over Nitrogen. This is if your using a tank and regulator. Whats available for smaller throwaway may be different but I found it to expensive but it did work.

The 250ml glass bottles work the best for me. YMMV

If you need any, I have an (there was a url link here which no longer exists).
 
There's a product to preserve wine. It's argon gas.

Dead Link Removed

I might be wrong, be air only degrades developers, not fixer nor stop baths. I don't try to preserve the 2 chemicals, only developers.
 
Yeah, cheaper than the wine preserver, but still expensive. Dektol is cheap, and it lasts a lot longer than Kodak says it will. Easiest thing to do is to store it in smaller bottles. Only the contents of a partially full small bottle are exposed to air at any one time. Cast off plastic pop bottles work just fine. Been using them for years and I've got no complaints.

http://www.youtube.com/watch?v=757g5qEs-bQ&feature=related
 


That's the best idea, I've heard in a long time. Did you patent this technique?
 
bvy said:
Is this true?
Click to expand...

I don't use any gas to protect chemicals. After processing, the working solutions go back into their dedicated bottles, are filled to the rim and tightly capped. If a little fluid was lost to evaporation or got soaked up by the paper, it is replaced with plain water. There is never more than a few cc of air in each bottle, and the surface area does not exceed the size of a silver dollar. I see no need to protect reusable chemicals. For non-reusable chemicals, I like tkamiya's proposal a lot.

Also, protective gas is not a complete protection. Developers change activity without necessarily oxidizing. D76 is a good example. Protection against oxidation is only of limited help. Also, never use a fridge to protect chemicals from aging. They may contain certain ingredients that fall out of solution when cooled below 10C. Bringing these chemical back into solution can be tough or impossible.
 
Mainecoonmaniac said:
... I might be wrong, be air only degrades developers, not fixer nor stop baths. ...
Click to expand...

bvy said:
Is this true?
Click to expand...

I don't know if it is literally true since most darkroom chemicals do eventually degrade. But it is true ti the extent that different solutions are challenged differently by exposure to atmosphere. Developers keep best when oxygen is kept away from them, hence if stored in plastic, use PET / PETE plastic bottles which have very low gas permeability. Stop and fix are less demanding.

According to: http://silvergrain.org/Photo-Tech/plastic.html "Use PET for developers. Use PET or HDPE for most other chemicals. If you store acetic acid stop bath in concentrated form, use HDPE." (A good basic primer on plastic bottles for storage of darkroom chemicals.)
 
Liquid Concentrates

bvy said:
My chemicals are Ilford PQ Paper Developer and
Ilford Rapid Fixer, both liquid concentrates.
Click to expand...

I've gone from liquid concentrates to 'dry concentrates'
for the same reason you've mentioned; chemistry growing
old on the shelf.

So I bought a good quality digital scale of modest capacity.
Now I brew partial batches occasionally and have on hand
very fresh chemistry. My one chemical fixer is fresh it's
day of use.

Judging from what chemistry you are now using five on
your shelf dry chemicals would be needed; metol, sodium
sulfite, sodium carbonate, potassium iodide, and for
contrast control and variety, hydroquinone. One
more, sodium thiosulfate; a slower to work
version of rapid fix.

Do some planning ahead and you may never again throw
chemistry gone bad down the drain. Dan
 
dancqu said:
...Judging from what chemistry you are now using five on
your shelf dry chemicals would be needed; metol, sodium
sulfite, sodium carbonate, potassium iodide, and ...
Click to expand...

I guess you meant bromide, not iodide Dan.
 
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