Have you a photo of the finished plug for us? How did you finish the plug?

Is it a polyester or epoxy mould? How old is your release agent? How many applications?

Is this body filler on the surface? That stuff is too porous for just a chemical mould release and needs to be sealed first with a mould sealer/primer.

Cheers, Lester

Are you shure you didn't sand through the high gloss coat? As said before, polyester filler is a highly problematic surface to take a mould from. How did you prepare the plug surface? Sanding till 1000-1500 and polishing afterwards? The smoother the surface, the better.
If your surface was shiny, and the filler didn't shine through, there has to be something wrong with the application of the release agent.
Polyester usually cures quite good without elevated temperatures.

Also bear in mind that some solvent based products (and some paints) continue to outgas for some time after initial cure.  The worse the outgassing the more likely it is to compromise the release agent and cause a sticker. Using 2 release agents can help and ultimately PVA can be used because it provides a physical barrier between the 2 materials.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I've managed to remove most of the plug from the moulds and at first thought it might be a mechanical lock but if this was so would it flake off after breaking a bit .
I sanded the plug with 1200 paper then high gloss coat and didn't sand through it .
There was no paint on the plug Warren ' only gell coat and high gloss coat.

1200 is wayyyy too fine for a pattern coating like high gloss coat. Need about 240 at the finest, preferably 180.

In any case, unless the plug came out of the mould and only left the gloss coat on the surface, then that isn't your issue - just thought I'd mention it.

Unless he sprayed it, wich would be very difficult because of the short pot life, he must have sanded after the final coat. The high gloss coat gives a nice finish, but not nice enough to go directly to the moulding.

If your plug was ok, and you used polyester tool coating (or vinylester) on a polyester plug surface, and never used 1 component products during the plug making, then it clearly comes down to the application of the release agent. Did the flanges stick together as well?