Can I pour liquid polyurethane casting resin directly over an epoxy tooling gel coat as a much faster way to make a split composite mould than by building up layers of fibreglass and resin as normal? It is a small mould so cost is not an issue.

Thanks for your reply. I have subsequently found some information from an Australian who has successfully done this using epoxy mixed with aluminium trihydroxide filler over a tooling epoxy. It was suggested that polyurethane casting resin would probably also work but had not been tried. The biggest consideration was avoidance of excessive exotherm due to the deep moulding by using a very slow curing catalyst.