Check the expiration date on the gelcoat. It sounds like the mekp is not
curing the entire batch.
Bruce

--
Shield Finishes and Nauticoat Marine Finish Systems
www.shieldfinishes.com
"Terry Spragg" wrote in message
...
Brian Nystrom wrote:
Evan Gatehouse wrote:

Yes - I think you got lucky the other times. Gelcoat is NOT supposed to
cure when applied over epoxy (i.e. the conventional wisdom)!


My experience has been that the "conventional wisdom" is simply wrong and
epoxy manufacturers agree. Once epoxy cures completely, it's inert, so it
shouldn't matter what you put over it unless it specifically reacts with
the epoxy chemically. I've used this particular combination of epoxy and
gelcoat successfully many times (literally from the same cans) and have
used other epoxies with this gelcoat, so I know from experience that it
works quite well.

Something has gone wrong this time, but I can't figure out what it is.
One suggestion I've been given is contamination in the epoxy or gelcoat.
That's possible, but I'm not sure what could have contaminated it.

Is it possible that the epoxy mix was rich in one or the other of the
components, some of which permeates the epoxy, and which cannot cure
without it's required co-component?

Might adding a little of the other cause it to set up to the point where
it actually becomes "inert?"

Might it then work better with the gelcoat as you would expect?

Or would it be better to remove the epoxy, recoat it with a more careful
mix of epoxy, then finish?

If one of the epoxy components has been around for a while is it possible
it has become "corked", that is, oxodized to the point where it is not
still the epoxy part you bought? Almost everything oxidizes over time. I
have had old polyester resin gum up, it seems to set up slowly with air,
humidity, or UV, sometimes. MEK is an oxidizer.

Have you done a subsequent test to see if this leftover old epoxy will
still set up under normal conditions?

It sounds like a contamination problem, you sure the dog didn't pee in
your mash, or summat?

Terry K