Quote Originally Posted by raoul View Post
Interested - but my main concern in all this is longevity of chems - particularly when opened to take out enough for a single run.
Opened but unused Tetenal concentrates last a very long time, they lasted over a year.

Concentrates last from my experience (as long as you don't allow contamination back in - if you pour too much out, don't pour it back in the bottle). Developer parts are acidic and preserved. Working solution is what will go off given the chance, though it still lasts a good amount of time.

Kodak concentrates - I received expired (in 2005) E-6 colour developer, still like new.