Hi

I am currently building a Datsun 240Z and wanted to make some of the parts from carbon fibre. The body shop repaired all of the body parts, sanded them and primiered them ready to be painted.
This is how it is now. 

So that the mold won't stick to the primer what is the best thing to do? Do I have to paint the parts or atleast clearcoat them?

Easy lease I found  working perfect on 2K primer !

PVA works also if you wont to have more shine in your moulds . 

Hi

Wow you guys are very quick!

So basically if i just wax the 2K primered body parts and use easyeasy lease, there should be little risk of the fiberglass mold sticking to the 2k primered steel parts?

Thanks for your help !

This are my first complex parts.  Until know I just made same small carbon patches on a sheet of glass, for sending them to get tested for street aproval.

Depends what your plans are ?
I guess your going to paint the primed panels ?
Since primer absorbs moisture your supposed to get your top coat on ASAP 
Why not top coat and mould off that ?
If you dont want to take your mould off the primer surface I would be tempted to vinyl wrap the panels an mould off that.
You can get vinyl fairly cheaply and it's easy to apply .
You apply PVA to the primer it really needs a release wax 1st an if you do that you will never get a top coat on there

@Lester Populaire Sure will keep project updated D:

@f1rob When I have the carbon fibre pieces i will not use the sheet metall parts. They where not in great shape anyways. They are just fixed so that hey are straight to get a mold of them.  

I am in a similar position to you. I have a matt finished car and I want to take a mold without waxing the matt finish on the plug parts. I was wondering if a very thin stretchy material maybe a bit like cling-film could be applied as a barrier? Anyone know of such a barrier film?
I think the glue on vinyl wrap would be difficult to remove from a matt surface.
Cliff  

Guys, with advanced composites always keep in mind: there's no shortcuts. You get out what you put in, so if you start cutting corners it will always reflect in the end product. Whether that is acceptable to you or not is up to you, but don't expect things to work flawlessly if you try to branch from the tried and tested. 

Vinyl wrap is not a suitable surface for mould making, any gelcoat containing styrene will attack it. The most appropriate solution if you really don't want to paint the primed panels is to spray PVA release agent, which then forms exactly the 'stretch cling film barrier' type of material that Cliff is seeking, and washes off with water when you are done. Yes, it will effect your surface finish with bits of dust and an imperfect gloss, you will need to refinish your mould if you are wanting perfection. It does spray pretty well with a bit of practise, so if you can keep the dust out of it then you may only need to rub the mould back with 1200 before compounding.  

I would always paint the primed parts before moulding and use a chemical release agent to get a perfect mould straight off the pattern. PVA does not work as well, but it is the one shortcut that I would consider if budget was the priority.