>Would someone give me an idea of how long basic chemicals
>last in the original jars, when opened and not opened. For
>example: I have some metol in an unopened container for
>about 15 years. Other chemicals, as well.
The general rule is if a chemical has been protected from exposure to
air and moisture, it is probably usable. Reducing agents by their very
nature are more subject to degradation from air and moisture than the
"sundry" chemicals used to make photo solutions. Amidol that has
oxidized to a black gunpowder appearance is useless. Dark brown pyro
should be avoided. However, metol and hydroquinone can be surprisingly
usable, even when they appear to have oxidized badly (brownish
appearance, sometimes with black flecks in the mix). I have used 50
year old metol and hydroquinone that were in Malinkrodt (sp) containers
from the 1930's. Both appeared to be in ugly shape. I mixed some D-72
paper developer with them, and they worked just fine! However, I didn't
have the guts to make film developer up with these old chemicals <<g>.
So a quick answer is, if it is old sodium/potassium sulfite,
sodium/potassium metabisulfite, sodium/potassium carbonate,
potassium/sodium bromide, boric acid, citric acid, and they have been
protected from moisture and air exposure, they should be ok. If it old
metol, hydroquinone, phenidone, ascorbic acid, or p-aminophenol with
the same protection, probably, but test on unimportant stuff. If it is
old pyrogallol, catechol, or amidol, I would throw it out. The final
three are especially tragic since they happen to be the most expensive
reducing agents. <<g> I hope this helps you.
Maxim M. Muir
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