Strange thing I noticed today - I have a bottle of nearly full KRST (1+3) that I keep around for negative toning (contrast control) and the bottle was doing one of those sucking itself in type of things. The darkroom has maybe had a variance of 10 deg F over the past month or so and humidity is relatively controlled around 60%. Anyone ever seen this before? I opened the cap and of course could hear the sucking in of new air and just re-tightened and put it back up on the shelf afterward. It doesn't bother me too much, but was just curious if anyone else has seen a similar effect.