: Hi John

: No it is a full 1/2 gallon plastic container, just no seal other than the
: cap. The container was visibly caved in a bit, enough for me to be sure I
: would have noticed it if it had been like this in the store. It also
: happened with System III containers that I thought I had sealed well. Not
: with a Fiberglass Hawaii home brand that came in an metal container. Just
: wondering if something can get through the plastic and if so, what.

If something was evaporating out, then it should do so with an increase in pressure. The bottle would expand as the gas came out of solution. Sounds to me like the hardener has started to polymerize (harden) on its own. Could be an oxiddation issue from any air in the top of the bottle, or it could be jsut the chemicals slowly reacting as they age. when the chemicals form bonds and link up, they take up a slightly smaller space. That could account for the shrinking you see in the contents.

The stuff should work as long as it is a liquid and mixes with the resin. I'd suggest you use the regular amount, not some adjusted volume. Or, mix it by weight. Any hardener which has started to react may be a bit less potent, not more concentrated.

PGJ