Refrigerating Chemicals

Brian Edwards · Oct 16, 2008

Does anyone have any experience with storing developer and other chemicals in a refrigerator (not a freezer)? Does it cause any problems?

Thanks.

Brian

Photo Engineer · Oct 16, 2008

Chemicals can precipitate out of solution and leave crystals on the bottom of the container. Then, when you go to use it, the solution is not corrrect. Warming sometimes does not redissolve the crystals and you have a problem.

It will work, but is sometimes counterproductive. It depends on the solution.

PE

Ian Grant · Oct 16, 2008

in 40+ years of photography I've never felt a need to refrigerate any chemicals, and in fact the only chemical that needed it was Lanthium Nitrate used for AA-spectroscopy of precious metals.

It's a waste of time & space. It may work in some instances but is not recommended anywhere.

Ian

dpurdy · Oct 16, 2008

I keep opened bottles of DDX in the fridge with marbles in the bottle and I doesn't seem to come out of solution at all and I feel better about keeping it a long time. I keep powder Glycin in the freezer and that seems to keep it from turning too brown. I also have been keeping some Dektol in stock solution in the freezer and I do find that it comes out of solution but when I dilute it with warm water and give it a stir it goes right back into solution. I also keep mixed bottles of Ferric Oxalate frozen and find that thawing it out is no problem and it works fine again.
Dennis

Paul Verizzo · Oct 16, 2008

I freeze D-76 w/o problem. I use it infrequently but like it for a reference developer. Take it out two days before you will use it and the precipitates all go back into solution.

Brian Edwards · Oct 16, 2008

Thanks for all of your responses.

I am particularly interested in D-76 and XTol, the two developers I use. I don't freeze it, but leave the stock solution in bottles in a refrigerator. When I am ready to develop, I add water (usually 1:1) and then allow the solution to come to developing temperature before using.

srs5694 · Oct 16, 2008

Brian Edwards said:
I am particularly interested in D-76 and XTol, the two developers I use. I don't freeze it, but leave the stock solution in bottles in a refrigerator. When I am ready to develop, I add water (usually 1:1) and then allow the solution to come to developing temperature before using.

I've heard of people mixing XTOL, and I believe also D-76, at twice the usual concentration (that is, mixing a 1-liter package to make 500ml, or similar modifications with other sizes). This should help longevity, but I don't have exact figures on it. I've done similar things with a mix-it-yourself C-41 developer and the mix-it-yourself DS-12 B&W developer and I'd guesstimate that it roughly doubles the shelf life. I don't know how this would affect the precipitation effects discussed here if you chose to freeze or refrigerate the extra-concentrated stock solution.

gainer · Oct 17, 2008

An icecube tray could be used as suggested earlier. The amount in each cube could be the amount usually diluted for use, or an even fraction of it. If it is all used, the concentration of ingredients in the final developer will be no les than normal. I don't know if the concentrated solution will freeze. If it does not, the advantage of the tray is lost. It would be better to use small bottles.

Adrian Twiss · Oct 18, 2008

I mix my own developers and was advised by Rayco to keep metol in the fridge. I also keep amidol in the fridge as well.

Paul Verizzo · Oct 18, 2008

Adrian Twiss said:
I mix my own developers and was advised by Rayco to keep metol in the fridge. I also keep amidol in the fridge as well.

Can't speak about Amidol, but there is no need to refrigerate any of the usual darkroom chemicals in dry form. I have Metol and many others from ca. 1985 doing just fine. Metol is known to pick up a slight pink-tan tint, but it doesn't effect the activity.

oldlugs · Oct 18, 2008

I agree about dry Metol not needing refrigeration; I've got about 10 pounds of 40+ year old Malincrokdt "Pictol" that's still working perfectly. It is a light tan in color, in the jar that I'm using from. My second 5 pound jar is still grayish white. BTW- I have 10 pound of Hydro the same 40+ age, and it's fine too. No refrigeration.

Wayne · Oct 18, 2008

Amidol is famous for keeping many decades in powder. I've seen hydroquinone go bad but that may have been from moisture more than age, and the RH is probably much higher in the fridge. While it may extend the life of liquids, I think its a bad practice to keep chemicals in a food refrigerator. One dedicated to that purpose would be better, unless there is zero chance of anyone but yourself ever getting into your fridge.

Wayne

Adrian Twiss · Oct 18, 2008

Wayne said:
Amidol is famous for keeping many decades in powder. I've seen hydroquinone go bad but that may have been from moisture more than age, and the RH is probably much higher in the fridge. While it may extend the life of liquids, I think its a bad practice to keep chemicals in a food refrigerator. One dedicated to that purpose would be better, unless there is zero chance of anyone but yourself ever getting into your fridge.

Wayne

I agree about the used of a dedicated refrigerator. I used to keep only film it it until I bought a chest freezer. Given possible moisture damage I think I'll remove my powedered chemicals from the fridge.

Paul Verizzo · Oct 18, 2008

The humidity is, um, relative. For the same RH, cooler air has less moisture absolute.

Most modern fridges are frost free in the freezer. That also keeps RH low in the main compartment.

All the chemical jars I've gotten in years have a polyethylene gasket cap. If you open the jar for only a few minutes to get at the contents, the moisture of the chemical will change little or not at all.

Metol makes a lousy Instant Breakfast, I hear.

Walter-NL · Oct 18, 2008

Light, oxygen, moisture pick-up and temperature may affect shelf life of chemicals. Freezing is eliminating the temperature effect and slowing down the other effects for a great deal but there is considerable risk of of irrevocable crystallisation. The solution for all other threats except for oxygen is obvious.

- Not all plastics show adequate oxygen barrier properties. Use glass bottles at all times!
- Fill bottles 100% as to lock out oxygen
- Flush partially filled bottles with inert gass. I use Argon which I have for GTAW welding anyway.

Wayne · Oct 18, 2008

Paul Verizzo said:
The humidity is, um, relative. For the same RH, cooler air has less moisture absolute.

Most modern fridges are frost free in the freezer. That also keeps RH low in the main compartment.

I know what RH is. If you take something to a lower RH, it often um, dries, even though there is more total moisture. I presume the converse to be true (subject to other conditions) but then I'm no physicist. If as you say humidity is low in the modern frost free fridge (I didn't know that) then of course it wouldn't be an issue.

Wayne

Refrigerating Chemicals

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