Converting from wet PE layup to epoxy infusion

All my molds are made from US Composites PE tooling gelcoat and PE laminating resin. I have a few hood/bonnet molds that I’d like to start infusing, likely with epoxy.

I’ve always used wax and PVA to treat my molds, but would I need to move to something like Frekote to prevent the epoxy form sticking to my molds?

Can I use regular PE gel coat, once hardened, infused epoxy to that. I’ve read and read and do’t find a straight answer. Do I need to step up to Duratec surfacing primer instead of PE gel coat?

Some of my 2-part molds would benefit from the gel coat layer to seal up the parting line for vacuum use.

My normal wet layup schedule with GP PE resin is:

PE gelcoat

.75 or 1.5oz csm

1708 or 2415 Stitchmat

My hoods would come out much thinner, stronger, and stiffer, with less followup repairs (voids in sharp corners) if I could step them up to epoxy infusion. But, I can’t risk the molds to having an epoxy layup get stuck inside.

You can infuse epoxy parts into your PE molds. switching to frekote isn’t a bad idea either since it sounds like you’re using them for production, however you’ll need to full treat and clean your molds to rid them of any left over wax before doing the initial frekote treatment (might as well use their FMS sealer too while you’re at it).

I usually utilize PE gelcoat and resins to build my molds for epoxy infusion parts and always utilize semi-permanent agent release to prevent any problem, it works perfect.

Because I want like you to benefit from the gelcoat to seal up the parting line I did some test with PE gel coat and lay up back with epoxy resin. The test was sucessful, so in next days I´ll go to infuse with this process.

I would suggest getting the mold cleaner (PMC), mold sealer (FMS), and a top coat such as WOLO if you are gelcoating the mold. If you don’t gelcoat, you might want to look at 770 for a top coat (epoxy is hard on the release system).

Also, I noted that at the bottom of your post you wrote that your parts will come out thinner, stronger, and stiffer. Thinner yes. Stronger and stiffer, not necessarily so, especially the stiffer part. Stiffness is a function of thickness. So, everything else being equal, if your part is thinner, it will almost certainly be less stiff.

On your point about voids, void content may improve but you need to make sure you are not just filling the void with resin. You must get the fiber into the corner prior to bagging. The bag won’t put the fiber where you want it to go. You have to put it there. A good trick I use on sharp corners is to use a few roving strands in the corner prior to the laminate.

Finally, you need to make sure your mat is compatible with the resin and the process you are using. Most mats are not compatible with epoxy and they can often foul up infusion flow.