Stuck part on 2nd pull

Doing a pair of small female moulds off of the same plug.

The plug is urethane tooling foam shot with Awlgrip 545 epoxy primer that was buffed to a gloss then wiped down with FreKote. I've used this combination several times before.

The part was done in brushing gelcoat then laminated with eglass/vinyester resin. A few layers of laminate at a time to be sure it didn't heat up too much.

The first pull was a complete success. No damage to the plug.

Next day, wiped the plug down again with FreKote (two coats) and did the 2nd layup. It is completely bonded to the plug. I'm chipping off foam now and will have to carefully sand to expose the part... this is going to take a whole lot of time but probably faster than starting from scratch with a new plug.

Question is, why would the 2nd pull go so wrong? This time it the laminate may have gotten a bit hotter, but not signficantly. That's the only difference I can think of.

Phil

 

Phil, maybe you can make a part from the mold you already made & make another pair of molds? Might be less frustrating than chipping away. I had some 2K paint stick up in a test once, just assumed some solvent entrapment gave it the "surface energy"(duratechs term) to hold on! Maybe I do the same silly old fashioned things but I've never tried semi/perm release agents & use ceara wax & PVA, the pva is like get out of jail free card in monopoly game of composites world but adds time & lower finish on nice molds & better finish on cr*ppy molds. It can only be the gelcoat stuck or maybee some resin sneek through some tripeing(alligatoring? to USA) & stick up due to longer gell time styrene attack to plug surface or gelcoat take too long to set up. Put your stick up out in the sun, might pop it or if that dont, drill a hole & blow off with air nothing to lose if every thing else tried. Hope you save it & all the best from Jeff.

 

Hadn't thought about using the good part to make a new plug etc. Good idea.

But about half a day of elbow grease and I've recovered the stuck part. The foam came off easy enough down to the 545 topcoat on it, which was absolutely bonded to the gelcoat. Still stumped as to why I'd get a near perfect first pull, and a disaster on the 2nd pull.