Bri said:
Hi everyone
Can anyone tell me if there is any merit in storing photographic chemicals in liquid form in the refrigerator, or will it damage them?
Thanks
Bri
Reducing the temperature will generally slow down any chemical reaction. With photo chemicals the oxidization reaction of developing agents is the one we are most concerned with.
The way to optimize photo chenistry storage is a multi-step approach. Refrigeration is but one approach.
Start with distilled or reverse osmosis filtered water for mixing developers. That means that the developing agent will only be reacting with the film, not any dissolved metals or gasses that came along with the water out of the tap.
Boil this water in a stainless steel (or otherwise non-reactive) pot, or a pyrex bowl in the microwave. Once well boiling, turn the heat off, cover it and let it cool. Store in a sealed glass jar/jug with a tight fitting lid.
This drives off oxygen that is dissolved in the gas that otherwise works its way into water over time, and keeps it out.
Stir your photo chemistry gently into the amount of stored cooled distilled water that you need. Don't try to whip all kinds of air in as you mix things up.
Top up to the required final volume with more cooled stored distilled water.
Store the prepared solution in filled glass containers. Polyseal caps are great , but if you don;'t have them on your bottles, put a bit of Saran Wrap over the top before putting the cap on.
If the developing agent is expensive, go the extra mile. I mix E-6 from a recipe from scratch, and the first and colour developers are involved, and contain some rather expensive chemistry. I top off even almost full bottles with nitrogen gas; an affordable way to get this is to go to a good wine store; they sell private preserve, or similar named products that aim to keep an opened bottle of wine from oxidising, which is the same thing that we are trying to keep our developers from doing before we expose them to film. Marbles work too, but I find they are a nuisance, compared to using gas.
Try to store the mixed product in a size of bottle that matches how you use it. Don't store partly used solutions and expect them to last like a new unused solution; once they are used there is film/paper residual product in the solution to carry oxidization along at a faster rate than if it were not there.
If you are aware of any components that are stored for a while before using, it is even feasible to almost fill plastic bottles and freeze them. I do this with unused portions of RA-4 developer if it is going to be a while until I get to using it. Short term unused product goes into amber boston round glassware that I only use for photo chemistry storage of developers, and keep them in the fridge. I label them, date them, and put a piece of tape over the top, and put them into the one fridge that we have in the house.
I never store in re-used food or beverage storage containers.
I do store used fix, bleach, and blix in separate reused windshield washer/deicer jugs bought new. When one fills up I pour it into a shallow stainless steel food warming type tray and put it on top of an outside cabinet that gets sun most of the day, and is under the eaves to avoid the rain. After a few weeks the solution has evaporated down to a sludge that gets scraped with a dedicated rubber spatula into a well labeled bottle that is then turned into the local hazardous waste collection depot that accepts it free of charge.
I have the luxury of a used magnetic stirrer, and if a formula or package says mix in 125 degree water, then the stored distilled water gets microwaved to that temp, and then mixed a good long while at a speed to avoid drawing air into the mixing solution to ensure that all components are thoroughly dissolved. I have not had situations where stuff re-crystallizes out after a stretch in the fridge or freezer for storage using this procedure.
