On Sat, 04 Jun 2005 11:04:58 +0000, Brian Nystrom wrote:

James wrote:
I would prob use the resin... but would certainly get new hardener.
Advice from a man who REALLY KNOWS the chem of epoxies suggests that the
resin is very stable but the hardener can degrade quite drasticly .. This
is apparently applicable to 99% of epoxy products regardless of who/where it
was made.

I've been told exactly the opposite by another epoxy manufacturer. They
claim that the resin has a limited life (as evidenced by
crystallization), but their hardener last indefinitely.

Crystallization is totally reversible, and the original poster said he
knows how to handle it. You can verify this by reading information from
bulk epoxy suppliers such as Resolution Performance Products, who now
supply the Epon epoxies which used to be supplied by Shell.

Here is the URL for a product bulletin about EPON Resin 828, which I think
is one of the most popular epoxy resins ever. Many epoxies that small
end users such as us can buy are probably based on EPON 828.

http://www.resins.com/resins/am/pdf/RP3075.pdf

A selected excerpt:

"EPON Resin 828 is susceptible to crystallization upon prolonged storage
at normal ambient temperatures. It may be reconstituted by warming to
120-140 F for 4-24 hours depending on the mass involved."

HTH.

BTW, if you are interested in learning more highly technical information
about epoxies, the resins.com website is a good place to sniff around. And
of course, Paul Oman seems to be a good resource, too. ;-)

--Mac