Now that the fault has been identified as oxidised developer, I thought I'd
just stick my hand up and repeat my observations on keeping the stuff
stored for long periods. The key is to keep oxygen away from the liquid,
the problem is how to do it.
Squeezy bottles work to some extent but you can still trap some air inside,
and they'll be trying to expand all the time, possibly sucking more air in
if there's the slightest lack of air-tightness.
I've found it's much better to displace the air above the liquid with some
sort of inert, or at least non-oxidising gas. Ideally, one which is
significantly more dense than air (rules out nitrogen - that's slightly
less dense).
Argon is perfect for the job, but unless you do a bit of welding you're
unlikely to have easy access to it. Fortunately, there's a readily
available, inexpensive alternative: butane. That's right, gas lighter
fuel. It's more dense even than argon, so it just sits on top of the
liquid, keeping any leftover air away. It's not even as big a fire hazard
as you might think, just keep away from flames & don't smoke whilst you top
up your developer bottles before you seal them again.
----------------------
Ian Nichols, School of Chemistry
I.A.Nichols@xxxxxxxxxxxxx
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