Hello all, Im new to the forum and new to making composite parts. I have made a couple of splitter vents for a race car of mine and now am working on brake cooling ducts for the front air dam. 

My question is how to lay up the carbon fiber to ensure a reasonable release from the mold. It currently looks like this:




I was thinking I could lay it up (after sanding and smoothing of course), as is, vacuum bag it, and essentially make it as one piece. But as I read a couple of other posts on this forum I started to second guess myself. Any suggestions from the collective?

Thanks in advance!

  

If you're happy with the basic shape, in that it doesn't pose the risk of a mechanical lock, after sanding back the filler/bondo it would probably be best lay a couple of light fibreglass layers over the pattern

Even if well coated with a suitable paint system, filler/bondo is likely to pull away when it comes to creating an initial mould so the fibreglass skin will add some strength. Once the fibreglass has been roughly sanded, a thin skim of filler can then be used to create a surface smooth enough to apply a top coat. 

The pattern coat primer and hi-coat gloss system that EC sells would be ideal, but some other kind of coating that can bond well to the bare pattern and provide a reliable release surface, after flatting and polishing, depending upon what's available where you are will also work

This will give you a female mould from which you can then create your final male mould using a tooling gel coat and fibreglass reinforcement