So better to use wax first then pva?

I ask because I have the same issue. I inherited a polyester mould and wiped it with 2 coats of pva.  Did the (epoxy) infusion last night and it was VERY hard to release the part.  I don't want to use the GC50, I don't think there is any need.

Hello

I have sprayed gelcoat for years with a automotive spray gun. (gravity feed)

The bigger the tip size the better. It comes out slower than a gelcoat gun, but you get the same result eventually. Some guys add a little acetone to thin, but I don't.

I now use a gelcoat gun which is worth every penny. Especially in how easy it is to clean up.

As far as laying up epoxy in a polyester mold there is 100% no problem with that. (it is all I ever do)

Just use good wax meant for composite work and PVA and you will have no problem with release.

The only reason to use epoxy for a mold is when great accuracey is needed because epoxy does not have the shrink rate factor that polyester has.

I have never needed that accuracey yet.

Just a tip about PVA. I apply PVA with a bunched up soft cloth just dripping with PVA.

I rub it in with circular motions. You will see it bead up, but just keep going over and over until it just stays shiney and does not bead up any more. It evaporates as you rub it out until it viscosity is thick eneough that it can't bead any more.

It is a fine line to know when to stop. But i aleays get a nice shiney film of PVA everytime I do it this way.  

When sprayed I get a beaded up mess.

Fred 

I got a answer to my first question by mail yesterday.

I copy it here so everyone can see:

"Yes, your suggestion would work. Because the GC50 is a polyester gelcoat, it will not have any problems release from your polyester bond so you do not need to worry about the fact that your mould is made from polyester."



About applying the gelcoat i am worried about that i cant brush a coat with the same thickness in a area that is 1.4 sqm

But buying a gelcoat gun is not a big cost in the process, so that is not any problem.



I am very happy for your aswers here, really good forum with a lots of things to learn and people that helps a beginner.

Best regards from Sweden

Magnus

 

Hi,

I had good luck spraying GC50 with a 3.9mm tip on a G100 spraygun.

Maybe you can spray the GC50 on a 2.5mm automotive spray gun, but it would need to be reduced with acetone, as I doubt a 2.5mm tip could take it as is. But then 2 problems come in mind:

01). I dont know if it is recommended to mix the GC50 polyester gelcoat with acetone. I know that you can do it with polyester filler with no problem tho. Plus I'm not so sure that your release agent will like the contact with acetone. Maybe the Easy Composite Staff could answer, or at least someone who already tried.

02). If you can reduce the GC50 with acetone, you take the risk to reduce it too much so it will "run" on vertical surfaces.

If you dont want to buy a new spraygun, best would be to simply use a brush as Matthieu recommends, while you should know that brushing the GC50 could lead to uneven thickness, and then lead to some milkiness on some areas. It will be especially visible in the sun light.

If you intend to make composites on the long run, a gelcoat spraygun is a good investment and you'll keep it forever as long as you just clean it after each use.

Hope it helps.

 



 


    A $1000 electronic device will always protect a 10 cents fuse

I have no experience in spraying gelcoat, always brush it on, but a gelcoat spraygun is next on my "to buy list" easier and better result :p

Matthieu Libeert
Founder MAT2 Composites X Sports
website: www.mat2composites.com

Thanks for your answer

I have think the same way as you.

But i need a 100% answer.

Can i apply that gelcoat with a spraygun for cars with a 2,5mm nozzle? Or must i have a special gelcoatspraygun with a larger nozzle?

Best regards

Should work I guess,

Hello

I´m gonna buy your infusionkit with epxy for making a roofpanel in carbon.

My problem is that my mold is in fiberglass and polyester.

What i have read is that not so good for use with epoxy? I read that the only soloution is to have PVA that isolate the polyester from the epxyresin?

But if i use https://www.easycomposites.co.uk/clearpol-iso-npg-clear-polyester-gelcoat

should that work? Becouse its a polyester gelcoat that work with epoxy.

I am thinking wrong? Or is that gonna work?

I am from Sweden so sorry if i spell wrong.

Best regards Magnus