Mold stuck in Plug! Help!

whata a load of smelly brown stuff !!

PVA in itself can cause problems. The two most common problems are the PVA etching into the mold surface and polystyrene hazing on the surface. Both problems are a result of thin PVA.

Sorry I am not going to let This go unchallenged its a lot of horse crap for more than 25 years I been spraying water diluted pva on moulds that have never seen a coat of wax and they release every time and the shine never changes ,Mould etching !! crap !! polystyrene hazing !! what a load of rubbish !! what you been smoking ??
How can PVA ETCH INTO A MOULDS SURFACE ?? HAZING HOW CAN IT CAUSE HAZING ??? GIVE ME A TRUTHFULL ANSWER !! IF YOU CAN !!

 

We could call it a load of tripe too...... but that wouldn't be quite right!
I don't really buy the PVA etching into the mold surface, I would buy into an incomplete misting of PVA allowing the gelcoat to "bite" into the mold surface in between the droplet pattern. I would accept that styrene from the gelcoat could cause hazing of the surface. There may well be further chemistry at work in the Rexco claims... not my feild(I just mix the stuff up)
What ever has been working for you tunnels is great for you, maybe you've always guaranteed a more complete cure of your tools surface through proper ratios/temperature/timing.
If for example our Irish mate Whacker( http://www.boatdesign.net/forums/fiberglass-composite-boat-building/boat-stuck-mould-43244-11.html ) had applied a nice thick wiped or multipass sprayed coating of a heavy PVA layer to his clinker rowboat mold he may have met with some success in releasing a hull & might have after the heat cycle of a couple of boats may have cured his mold to a less reactive state & enjoyed the process.
All the best from Jeff.

 

Workmanship has a lot to do with just about any problems associated with failures in fibreglass !!Whacker was one in a million , he was not telling the truth of that i am quite sure ,saying one thing and doing something else completely different and telling us mixed truths , I have read those posts a dozen times ,no mater what mood im in I cant put my finger on what he was actually doing !!

Spraying the water diluted PVA like I do is absolutely impossible not to get 110% coverage on any shaped mould no mater how big or small The air carries the water and pva even up to 6 feet or more away ,and because the water takes a few minutes to dry there's no dry edges any where ! once it is dried its possible to blow dry your hand and ever so gently wipe across the mould surface and you can feel the pva grip you skin even though you cant see it ,it has a different feel !!.

As for cured gel coat am always doing what should be done !!1,5% of the manufactures recommended catalyst well stirred and allowed to sit for a couple of minutes before spraying or brushing , temperature at 20c and get a gel time of 35 minutes plus never fails !! its what recommended and you get the results .
The only deviation is for a second coat I always add a small percentage of laminating resin to the gel coat to give a better surface finish , since I been adding resin the alligator problem vanished completely even on the very outside of the edges of mould that are always thin it never happens ! don't ask why because I don't know !!