If you are having trouble with the polyester resin not totally hardening....
Make sure you are not using a laminating resin!

Laminating resin does not produce a waxy substance at it's surface like regular resin.

Polyester resin will not harden at the air/polyester interface because air inhibits the chemical reaction. Additives in finishing resins produce a waxy surface and seal the surface from the air allowing it to totally harden.

The laminating resin is used when additional layers are to be bonded to the surface later and stays gooey on top.

If finishing resin is used and requires additional layers later, then the waxy film must be removed first and it takes some fairly serious measures to remove all the wax and prep the surface for a good bond.

I am not a big fan of polyester resins, I use epoxy almost exclusively (most epoxies produce the amine blush also). But at times cost is a bigger factor.

This may or may not be what is happening when your resins don't harden (not enough catalyst will cause a problem too) but maybe it will help anyway!

Doug K.

: Hi everybody,
: I have just finished my mold for a seat formed to me, it is made with
: fiberglass matt and epoxy resin, but I was wondering, to save on very
: expensive epoxy, should the actual seat be made from cheaper fiberglass or
: epoxy, I plan on using copy toner for a black look and I figured that sun
: damage would not be much of a problem because the seat would be almost
: always covered by a spray skirt or my back side. Is fiberglass a better
: material? So far I haven't had much luck getting the mixture right, the
: stuff either gels up in the mix cup or it does not dry. Any thoughts?
: Thanks.