Do I need to use PVA on a plug thats been finished in duratec PE surfacing primer (with or without high gloss additive mixed in) or can I simpy wax (8-10 coats) the plug (polished to a shine) with a good release wax? For the mold construction I will be brushing (or spraying if brushing is bad) a PE tooling gel coat followed by multi layers of CSM & PE resin. I dont want to risk the mold sticking to the plug but I’d rather avoid PVA if at all possible.
I always use the high gloss add. with the primer and have used wax only (partall #2) or semi perms (frekote and sealer). PVA is the enemy in my book and never have used it with Duratec. 
FYI. The plug is always class A before I release coat.
def use semi-permanent release such as frekote, the results will be so much better and save time. Never use PVA except in very very rare cases such as very old molds that are beat up.
Yeah, it’s well known by some. There are other cases too. Some times you just have to know where to look.
Thanks for the responses guys! (Abervalger: I’m confused by your response) Here is a silly question: If I polish the plug (duratec only) then use a semi-permanent release such as frekote will I still be able to (after the mold has been pulled) lightly sand the areas coated with the semi-perm before re-priming/painting the wing (and have no issues with the primer/paint not sticking)?
You can remove it. Sanding and polishing will remove a semi-permanent. Use a grease/wax remover afterwards to remove any infected dust paticles and residues. I’ve painted surfaces before that were once treated with Frekote.
Thanks Wyowindworks! What do you think of this (Is this the correct chronological order?):
- Sand the plugs with progressively finer paper, ending at 1200-1500 grit
- Polish the plugs to a glossy shine with polishing compound
- Apply at least 10 coats of a good release wax (wait 1hr between coats and dont rub too hard and remove all the wax when buffing each coat off the plugs)
- Wipe on a semi perm realease agent
- Begin laying up the molds (PE tooling gelcoat… lightweight layer of glass with VE resin, then add bulk layers with PE tooling resin)
Questions:
- What brand semi perm do you recommend I use? I need something that I can purchase in small quantities
- Do I need to seal the primer before waxing/adding the semi perm (if so what should I use to seal?)?
- Do I have the sequence correct? As in: Sand, Polish, Wax, Semi Perm
- Am I missing anything?
Semi perms are nice because they release easier then wax and last longer. A seasoned wax mould releases easy but that’s not what you are using.
Thanks for the fast response Rotorage! One last bit of clarification: I’m good to go applying the sealer, then semi perm directly over the polished primer plug right? My first step when laying up the mold will be to brush/roll on some PE tooling gel coat followed by a light layer of fabric/veil with VE resin (per Herman) then bulk up via CSM & PE tooling resin.
Any tips for applying the sealer/semi perm?
Also, a bit off topic (I asked this question in another post): Is there a good reason I should stick with the Duratec PE primer vs using Dupont’s 13850S epoxy primer for my plugs? I have both on hand but the pot life on the duratec is only about 7 min at 105 degrees…
What finish do you want your final part to be class A? If you plug is class A finish then you are ready to seal and apply semi perm. After the semi perm is dry you can apply your gel coats and veils.
My tips for appling the sealer and semi perm are not the best but worked for me. I hope Wyowindworks and others will chime in. I just use terry cloths to apply and buff. Dallas had some good tricks to apply the semi perm with out letting it haze, but I never tried it. I just wipe on let dry, and buff the haze to a gloss. After a few coats I try to stick a piece of masking tape to the released area and it shouldn’t stick and just slide. Hojo taught me that trick. You will want to apply alittle more release where you just put the tape to ensure no contamination. It’s basically like waxing your car, wipe on wipe off.
I have no answer for the dupont question I’ve never used it.
I’d recommend following the directions for your semi-permanent release system and use the recommended sealer. It’s amazing how many people have issues because they didn’t follow the directions.
The one deviation that I make with Frekote 770-nc is that I wipe the excess release off right after wiping it on. If you wipe on and wipe off you won’t get the streaking issues. I wipe the excess FMS sealer off when I notice the edges start to evaporate. I’ve never had hazing issues until the release surface has undergone 50 or 60 cycles. The haze has never really bothered me though. If the mold is hazy the parts come out a little hazy but 1 minute with Meguiar’s Swirl Remover 2.0 and hand work removes the haze easily (don’t use the Swirl remover on the release surface or you will take the release right off). I do the same thing to a new mold surface that has been pulled from a plug treated with Frekote.
Since you are trying to avoid having to polish the mold you need to be careful when making the mold. If you move to heavy fabrics too soon in the layup or demold the mold too soon you will get fabric printing through to the mold surface. I always wait at least 4 days before I pull a mold from the plug…although I use slower curing epoxies.