: I was a little embarrassed the other day when a couple of posts told me about
: the sizing thing. It was the first time I ever heard of it. I have already
: glassed my rudder with the Wal-Mart glass and two coats of epoxy so far
: and haven't seen any problems to speak of. I applied the first coat, laid
: the glass on and padded it until the epoxy wetted through the cloth. It
: all looked good and the glass laid flat and tight around the radiuses. I
: put my second coat on in the sun room which was freezing 32 degrees and as
: the sun came out strong the room got up to 45 and I started getting what I
: believe is out gassing and my surface is pimply right now before I sand it
: this morning. But since I had a first coat of epoxy on I wouldn't have
: thought there would be an outgassing. I assume it is this tricky weather I
: am working in but don't really know.

: John

Well the normal mat is stuck together with styrene (mixed with some other junk), it's possible that the epoxy you're using is reacting with the binder but I doubt it.

Btw, even with improperly sized mat (or cloth for that matter) the resin will usually eventually soften the binder so that it'll drape, just takes a really long time compared to using the resin that it was designed to be used with.

Couple other things about mat to remember, the strands are very short compared to cloth so the stength is fairly low in comparison and mat's published weight is different from cloth/roving etc. Cloth is sold be ounces per square yard. Mat is sold by ounces per square foot. (don't ask me why, have no idea).

Bill H.