Polyester resins contain about 50% or so of styrene, VE contain a little less, like 35-50%. Adding 5% of styrene will give you roughly another 1% of shrinkage (volume reduction). Doesn't sound like much, considering those resins already shrink 5-10%, but it adds up.
Epoxies have a volume reduction of roughly 3-5%, which is 2-3 times better.
All numbers are only rule of thumb, don't take them as absolute.

Try to find epoxy infusion resin, or alternatively the lowest viscosity epoxy resin and a low viscosity (slow) hardener, that should work, too. No slots in the core, and use some post curing in the mold, then most problems should go away.

> Amorim Corecork

Interesting. I've seen it a few years ago at the Composites Europe trade show and grabbed a small box of samples but never used it myself.

I love it. Absolutely no reason to go back to using Soric, it's better in every way. 

Interesting, have you done any structural testing?

Warren

Carbon Copies Ltd

No as yet, no. I have been meaning to do some more of my crude testing, just haven't got round to it. Certainly the tech data sheet makes it sound the goods. More info here:

UK supplier, nice guys too

****Not quite sure why you would actually want shrinkage?
As this is racecar bodywork and you say weight is critical I would have waited the three weeks for the epoxy infusion resin. Result would be a stronger and lighter part with much less/zero print through.***




Well I need to lengthen my wheel base so with the shrinkage in length of the body it negated me from having to make changes. (long Story but it worked)

The reason why I'm using Vinyl Ester is the stiffness, Epoxy doesn't have the same rigidity as Vinyl Ester especially on the rear section where it is going to see engine bay heat.

Further more Epoxy seems to be silly expensive lately

not sure but as far as i know epoxy is more rigid that vinylester... vinylester will be more chemical resistant and heat resistant in some ways