PVA beads up

The extra information about the wax is revealing as it is good practice to avoid silicone and generally the better waxes are based on carnauba wax.However the piece has been moulded now.It is very common and almost universal to compound a new mould as the tiny grooves left by the finest abrasive are turned into very fine ridges and flatten very easily.It isn't essential to use an air tool for polishing as the object of the exercise is to move the compound and it doesn't have to be a rotary movement.A piece of rag rubbed vigorously with a finger will do the job and if you need to get into a very tight corner you can use a rag wrapped round a small piece of plastic tube.

 

OK well its still a tad hazy with tiny scratches after compounding it and putting a wax over it, I feel I cant polish as good by hand but anyways I will spray some PVA and gel coat into it tomorrow possible and see how the part pops out of the mold

 

You can see I am using a cheap turtle wax compound, you can see replection at and angle but there are other areas that are foggy like the left side of it, I will need to spray the PVA well because otherwise it doesnt matter how glossy the mold is the gelcoat will shape to the PVA, Im not trying to put parts off with only wax for now lol

 

PVA is an insurance coat when the mold is new. That is when we suspect the mold has not fully cured and there are some volatiles still in it. We use hot water to dilute it to get the proper mist when spraying. The coating is dull and will not give you a mirror like finish.

With a properly broken in mold, I eliminate PVA. I have used floor wax in a bind, Just made sure it has beeswax in it. Release is not as good as the commercial wax but at least the part did not stick to the mold. And the part is shiny. I would not recommend it as a substitute for regular release wax though.

 

So you are saying generally using wax only is more glossy that PVA over the wax? Would any "Partall" wax work well?

 

I have used the green Partall PVA liquid but not Partall wax. Wax can be polished to a high gloss but not PVA. Once you have sprayed it, you cannot touch it.

 

@rxcomposite may I ask please how much water you put with PVA when spraying it? Let's say in 100 gr of PVA, what is the recommended analogy?

Also with a 1.5 gun nose what is the recommended pressure from your experience?

 

Anywhere from 20% to 30% of hot water then stir to mix well. The distance of the gun to the surface and the gun tip size varies. You will have to get the feel. We use hot water to remove the remaining Partall after demolding.

It is the remaining unevaporated MEKP that is the culprit. It remains in the mold, goes past the wax and attack the gel coat and resin laminate. Partall forms a barrier.

 

Why put water in PVA??

 

Following up on this thread...
The turtle wax I used had silicone in it so the PVA did not adhere well, I have used non-silicone wax since then and had no issues !!

 

Why?

 

Yes tell me what is the point of putting water in with PVA? What benefit does that have?

 

Got truncated.
Why? Have you ever tried to spray PVA in its unadulterated form?

 

Yes I have only sprayed it without adding anything else...

 

It can be sprayed without water, but a bit of water can make life much easier.

In low humidity high elevation locations I've seen PVA spray like cotton candy. Or with high humidity take for ever to become tack free. You adjust the amount of water as needed for your current conditions.