Quote Originally Posted by Simonh82 View Post

I've read on here that the working solutions last much longer than the concentrates which I find really hard to believe.
Yes, it has been posted many times on this forum that working solutions of color developers, stored in glass (and possibly high quality plastic) jars filled to the top can have a very long life as oxidation is minimized. I use glass canning jars, readily available in different sizes. I always mix the whole amount at once and stored this way I have had RA-4 and C-41 developers last more than three years with results indistinguishable from fresh, and little change in color of the chemistry.