I used pva on a very slick plug and now sanding stroke marks out of my gelcoat. It appeared to lay rather smoothly applied with a sponge brush but obviously not. i have sprayed it before and didnt really like that finish either. Can I get away with not using it? Alternitives? I want my parts to be as slick as my mould.Tired of sanding… Help… Thanks
Yes, don’t use PVA, use a semi permanent sealer and release agent such as Frekote, or Axel. PVA is only good for splashing moulds off of original parts that are painted, or really old plugs/moulds. Using PVA on a plug that you spend many hours perfecting just to put an interface between the plug and mould that creates imperfections makes no sense. And if you have to use PVA, spray it on in light mist layers.
Indeed. Ditch the PVA. It is only good for the most doubtful releases.
Need to finish these quickly. Can I get by with a few coats of partall#2 on polished mould? Epoxy gelcoat mould,wet carbon layup,vac bagged.Goning to be a few days on frekote.Hate to ruin mould in haste.Thanks
Frekote is not so great… Both PVA and Frekote have + and -
Frekote gives very easy release especially good in complicated shapes , but it is also a disadvantage because gelcoats / clear coats often slips off of the mould.
Pva dont give great release but release is permanent, it also leaves marks on surfaces
PVA always need finishing job so I only use it on wax sheet molding or on some parts or plug that I know I must do an essential finishing job in order to doesn’t wast expensive semi perm.
After many try he best way,IMO, I’ve found is to spray it:
-nozzle between 1,4 and 1,7mm
-pressure around 4/5bar
-starting by spraying thin veil on 3/4 layers
-open a bit the PVA flow on the last 2/3 layers
-leave it dry greatly between each layer
-try to never overload, I try to apply with the same atention that a final varnish …at htis time I sometimes think: bloody idiot why you don’t have use the magic and quick applying sealer+semi perm!!! 
If well apply only some little hole or little fish eye appears
Hope that could help you
Thanks all. Im sanded to 1000 and polished 5 coats partall#2. Scared that will not be enough and have trouble seperating.Not a complex part but not sure. Guess I wait on semi-perm.
if in question, do a small test area so that you do not ruin the mould. When you use a semi-permanent release, you can do a tape test to confirm the application