: Hi Hank,
: I'm not sure I understand, did the container itself shrink, or did the
: contents shrink?
: Here in Australia West Systems hardener (no MAS) come in bottles half full.
: Is that the case with MAS also? If so how did you determine that there is
: evaporation?
: JohnK

I've had the bottles cave in on me several times. In my case, it happens from storing the epoxy outdoors where it gets hot and cold. When it gets hot, the air expands and bleeds out then when it gets cold, the bottle caves in a little. What is worse is if I store the epoxy with the pumps still in them. Then the hot/cold differential makes the epoxy leak out of the pumps and makes a sticky mess to clean up.