: This is a little bit off subject, but I'll ask anyway. I don't think I'll
: have enough MAS epoxy to do the fill coats on my yak, but I have enough to
: do all the fiberglassing. I have a supply of WEST that I can use, not a
: lot, but at least half a gallon. Is it OK to use WEST as a filler if I
: wait a while and scrub, then sand very lightly to create a mech bond? I
: have a while to think about it, but thought I would ask. If need be, I can
: buy more MAS epoxy.

Chuck,
I used the MAS epoxy as a filler throughout this project, and System 3 primarily for wet out and weave fills precisely for the same reasons you mention above. It worked fine, as long as I gave the MAS a chance to harden completely. Any time I didn't, I ran into problems...I think the standard 3 day cure time as it relates to sanding still applies.
Bill