I have been making CF-foam-CF sandwiches using the resin infusion method, which involves using a layer of peel-ply under the infusion mesh. This leaves my panels with one smooth side (against the tool surface) and a rough side (courtesy of the peel ply.)

Is it possible to replace the peel-ply with, say, Perforated Release Film (or similar) to give a smoother finish? I'm not looking for a perfectly smooth/glossy surface, just not a peel-ply finish.

Would Perforated Release Film (as used in wet lay-ups) allow the resin to permiate through to the CF-foam-CF sandwich beneath or would you just end up sucking the majority of your resin into the catch pot?

Any advice appreciated.

Phil.

Im not sure how well the film would release from the carbon. someone else might know.

To ensure the resin flows fully throughout the lay up, you want a release film with a high density of holes.  Something like bread wrap works very well, even if slightly overlapped in corners. 

However you need to be careful when you use films such as P3 spaced release film that you dont overlap it too much or flow the resintoo quick as it needs a bit of time to allow the resin to permeate through into the carbon.

Also remember to prepare your foam core with holes and scoring to allow resin flow to the bottom of the lay up. Obviously that is not needed on something like soric where it already has open areas for resin flow.

Hi Philip,

P3 film won't allow enough resin down into the laminate. It will, as you've guessed, mean that resin will stay on top of the film and race through the peel ply and mesh to the vacuum line without wetting out the laminate before it gets there. Warren wasn't sure how well the relase film would come away from the resin - although it's academic in this particular situation the answer is that it release completely and utterly perfectly. Release film simply will not stick to resin in any way, it literally falls away. Worth remembering for lots of other situations where release film can be very handy stuff.

Warren's right about breadwrap, it does allow resin to pass through much more easily but there are a few issues with this. When we use breadwrap in an infusion (which isn't that often) we use it as a barrier between the infusion mesh and the peel ply (which is against the laminate). By doing this, it makes separating the the mesh from the peel ply much easier which in turn makes separating the peel ply from the part easier.

The bottom line is that resin infusion, done in the normal way, doesn't lend itself to creating a 'double a-side'. Depending on the part that you're trying to make, and your determination to have a part that has a double a-side when it comes out of the mould, you could create a matched-tool (a male and female mould that come together, a bit like RTM) and then use an internal flow media (like Soric but others are available) so that you don't need to use a peel-ply and mesh at all. In this way, you could certainly have a double a-side part with no trace of peel-ply.

I hpe this helps.

Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Thanks Matt - that's much as I suspected - at least your confirmation saves me from having to knock up a trial-and-error test piece :- )

I think I'll live with the peel-ply finish as the alternative is more work than it's worth for a non-cosmetic piece!

Thanks,

Phil.