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

: Oops I left my MAS epoxy and hardener (2:1) outside for about 4 months in the
: California weather, sun, ash rains after the fires again and again,
: etcetera. They were covered by a tarp thankfully. The can with hardener
: has shrunk some, I estimate about 10%. It was never opened. Any idea what
: has vaporized? I think I will keep using it anyway at a slightly changed
: ratio regardless since I like to learn the hard way. Unless anybody
: convinces me I should not.

: Thanks for any advice,

: Henk

: PS I also found that plastic cans with System III hardener and resin can cave
: in over time. I hate to dispose of toxic chemicals, curious what causes
: this and how bad it is to keep using it.