How sensitive are various chemicals to light, air, etc?

Hi,

Unfortunately I only get around pretty infrequently to develop film, and even then only relatively small quantities. Of course I need to store my chemicals in the mean time.

Wherever I look, I only find some generic descriptions, like "keep you chemicals in dark, air-tight containers". While I try to do so - I keep my chemicals in a box, in a usually dark storage area, tightly closed - my methods are far from perfect. While I will try to squeeze some air out of the plastic bottles, this process works only so far until they are more than half empty. Also, while my developer sits in a somewhat opaque bottle, the fixer's bottle is quite transparent.

Basically, my question would be, in what way are chemicals (diluted or not) affected by light and contact with air (in a closed bottle).

Currently I have undiluted Rodinal (Foma R09), undiluted Fomafix fixer and a mixed batch of Fomadon Excel (that is supposed to be an XTOL alternative). [as we have a Foma distribuitor in town, but unfortunately not much else can be found easily]

keli said:

Currently I have undiluted Rodinal (Foma R09), undiluted Fomafix fixer and a mixed batch of Fomadon Excel (that is supposed to be an XTOL alternative). [as we have a Foma distribuitor in town, but unfortunately not much else can be found easily]

Click to expand...

Hi and welcome to apug

Don't worry about rodinal - it is lasting very long. I am using Ilford and Foma fixer, I keep undiluted stuff in fridge for months, never had any problems.

Hello and welcome Keli.

Dark or opaque bottles are not needed, as long as you store your chemicals in a dark place. No light, no problem, if light may deteriorate any chemical you have. The most important thing about storage is the air enclosed in the bottle. If you're worried about it, you can always decant in smaller bottles, filled to the rim. Your bottles should be air tight and many people (including me) successfully use fizzy drink bottles for that purpose.

Now, regarding the life of your chemicals, I'd say Foma R09 should last some years, but AFAIK nowhere near the figures said about Agfa's Rodinal. Fomadon Excel will probably be gone within 6 months, better use it quickly. Finally, fixers have quite long life, but can certainly go bad. The good thing is that you can always test with a piece of film before doing any serious work. In any case, check for precipitate in the fixer. If you see some, chances are that sulfur has precipitated and you should toss it. Even if it fixes film, it will probably deposit precipitate on it and you will *never* be able to remove it. Recently I opened a sealed bottle of Ilford Hypam fixer, god knows how old it was, I got it free. The inner surface of the bottle was covered with a yellow crystalline layer. Needless to say it was tossed...

Fresh and/or Very Recent Chemistry

I too am in the darkroom off, off, off, and on.
Years ago I loaded up on chemistry only to
see much of it go bad.

So I decided to swing for a good quality scale.
A accurate small capacity scale will allow you
to brew up fresh chemistry when needed.
One never-goes-bad chemical does for
fresh fixer each session. Dan

Caps Are Important

Alessandro Serrao said:

Best are dark amber glass bottles for storing everything,
such these http://www.thesage.com/images/prod/119-40xx.jpg

Use everything one-shot and you'll avoid 90% of common
problems found in processing.

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I've a bunch of amber glass Boston Rounds, narrow and
wide mouth. All are equipped with Polyseal or Polycone
caps. I doubt a more sure seal exists. Boston Rounds
are a standard for chemical storage. They are not
expensive.

I split larger quantities into smaller bottles, usually
ending up with just the amount for one session;
one-shot use. Planning the session ahead
can reduce wast to Zero. Dan