Fiberglassing PVC foam

Hi,
I've done a lot of fiberglassing timber, but am new to foam cores.
When I laminate glass to foam should I first coat the foam with thickened resin to fill the cells or can I just fiberglass straight to the raw foam?

Cheers
Mick

 

You should have a complete laminate schedule organized for your project before you start, but in normal practice on non-scored sheet foam, a resin-rich layer of lightweight mat would be used, to get a good tie between the foam and the following lamination.

 

That would depend on the resin.

 

I assume he is not using epoxy, but possibly wrongly !

 

Could be vinylester, which has better adhesion than polyester.

 

Best he clarifies that himself.

 

Will be with polyester resin

 

An extension to the question.
When laminating over a mould, foam cores come after gelcoat and few layers of fiberglass. In that case how are we going to fix the core with the fiberglass layers? Need special adhesives? I'm also talking about polyester resin.
By the way I'm trying to switch to foam core construction, stopping the solid fiberglass method. Through my estimates i found that it is less expensive and lighter given same strength. Got any objection to my estimates?

 

It depends how you define strength. A solid laminate is usually more puncture resistant for the same stiffness. A cored laminate is usually lighter. Both need to be engineered for the application; there is no generic answer. The core can be bedded in some of a variety of adhesives or resins depending on your laminating method. Are you hand laying the fiberglass? If you are, at least consider vacuum bagging the core.