Everytime it seems as though the PVA causes a slight orange peel appearance on my parts. The worst was on the mold I just made for a jetski hood. I’m always having to polish this out. Can I just get away with using mold release wax only?
Thanks
Just use wax. It will work fine as long as it’s applied properly.
I don’t know why people insist on using PVA. It’s crap.
I never got orange peel by using my PVA.
Spraying PVA can be a PITA and once mastered, works great.
I only use it if I have not semi pernament coat a new mold without heat cycle the mold or a plug that I have questions if it will release properly or not.
I can get my pva finish pretty good now but it took some practice. It will depend what your plug surface coat is. Some paints/primers absorb the wax and will stick to your mold unable to demold. Ive also had a gelcoat reaction with the plug primer causing causing weird cracking and a non cure, which pva would have stopped. I only use just wax when the plug is finished with a gel/flowcoat with at least a 3 day cure.
pva is the only thing that safeguards you from any kind of mishap. spraying it is a bit of a technique, but i can brag now, i have mastered it.
first thing, you have to use a priming wax. that is a liquid wax that stinks awefully. you apply it with a brush or cloth, and after a few minutes, before it dries, you wipe it. it doesnt polish like the other waxes, like meguiars for example, leaves a dull finish. you just wipe it so there wont be any lines from applying it. this serves as a base for the pva.
then you spray a mist of pva, at 3 bar pressure. let it set for like 5 minutes, and again. do this 4-5 times, letting it dry in between, and it will start to make a surface. then add a bit more material on the gun, go a little closer, and spray some more heavily. remember to let it dry in between sprays. after a while you will see that the surface becomes even and glossy. when the color of the pva is deep enough, like on a white part, its leaf green, you re done. let it dry for an hour or so and start your work.
what i love about pva besides the safety, is that it makes even the worst parts or molds, glossy. And parts that are hard to demold with wax because the surface is damaged or rough, are damn easy with pva. i know,molds should have a perfect surface but hey, i didnt know how to make perfect molds since day one… :rolleyes:
I’ve always just wiped it on with shop paper towels, no orange peel, great finish.
I’ve had random issues with pva, but never getting orange peel, maybe once when I was very very careless.
But I’ve wiped it on with good results but I think spraying is still the way to go. If you can get clear coat to lay down decently “which I can” then you can get pva to lay down too.
Right now I have 2 plugs though without pva, we’ll see how they turn out.
Colour your PVA with ink, so at least you can see what you are doing.
Or do not use it at all…
I don’t use PVA I have had good luck with perma seal and wax.
The need for PVA is really dependent on the release surface and the resin. To say that PVA is not necessary would be misleading unless other criteria is given. The internet is covered with photos of epic sticks from people who used just wax.
What is the release surface comprised of? Resin? Paint? What kind of resins are being use? Has the surface been prepped with a sealer and what kind?
I can definitely attest to certain surfaces and resins reacting and sticking like mad with just wax. Wax cannot block the chemical reactivity between certain produces…no matter how many coats you apply. PVA is the only way to block reactivity with some combinations.
If you have access to Part-all Paste #2 and Part-all Film #10 (PVA) then no priming wax or misting coats are necessary. Just shoot a flowing coat right off the bat and be done.
Orange peel is usually caused by the produce being too viscous or drying too quickly. Adding 5 or 10% water can reduce the viscosity and slow the drying.
I just use a very high quality chemical release agent, such as EasyLease. However, I used PVA when making certain moulds, since the the EasyLease is so repellant that gelcoat will run off and pool resulting in an uneven coating of tooling gel.
On parts, I just use EasyLease, it is compatible with any resin system and is high gloss. No need for wax at all.
cheers
So I’ll forever use pva on my plugs. My mould turned out great but a few spots on my primed surface/clear coat stuck to my mould. I’ve been using acetone and a broken pen to scrape it off the mould. Stuff is really stuck in some places!
For mould making from plugs I usually recommend a semi perm sealer, and Meguiars M87 over it. No repelling, excellent release.
I was recently experimenting with a plug surface and discovered that if done carefully, wax (mothers 05550)can actually be applied after the pva is dry. The orange peel appearance remains somewhat visible, but the slight texture is nearly eliminated.