Hi,

I am exploring ways of creating patterns which I can use to directly layup carbon fabric with epoxy resin to given me the carbon component. The pattern relates to a small part the length and breadth of an A5 piece of paper.

I have created one pattern with balsa wood and pine then adding some P38 filler to achieve a smooth surface.

My next step is to prepare the surface of the pattern ready for laying up. I am very interested to hear what product would be best suited to achieve this. I do not need a perfect surface finish but would like a surface that allows for easy mould release from the cured epoxy resin/carbon fabric that I will be using.

Would the Epoxy Coating Resins be suitable here? Then once set to the pattern would the only other step be to coat in wax?

Similarly I may make the same pattern in machined acrylic. However, I would still need to use P38 filler to fill in gaps and so I wandered if I still need a sealing coat on top or if just a wax would do? In the case that I still need a surface coat do you think that the same Epoxy Coating Resin would work well here?

I should add that I have polyester resin as another option of achieving a surface finish in both the wood and plastic pattern - would this be advisable considering I am laying up with epoxy resin with carbon fabric?

Thanks,
Kristoff

Hi Kristoff,

If your shape is pretty simple, like a smooth curve, then the simplest method would simply be to wrap the pattern in release film pulled tight over it and then taped down at the back. Our release film is stretchy enough to mean that it can be pulled tight over simple shapes like this without any wrinkles or creases. If this is a long-term moulding surface then you might want something more permanent but if it's just to make a few parts and the shape is appropriate then release film is a bulletproof way of ensuring that your parts release perfectly and only takes a few seconds to do.

If you don't think release film would be appropriate then the first choice in a workshop environment is 2-pack (2k) filler primer. You buy this from a car paint supplier and it needs to be mixed and then sprayed through a gun. Because it needs spraying it's often not used for small projects like this but I thought I'd mention it because it is one of the more common way to finish a pattern in the industry.

Given that you'll be laminating epoxy onto this pattern I would say that it would be a good idea to have a barrier between the polyester bodyfiller and the epoxy, more of a barrier than release agent alone can provide and for this reason our Epoxy Coating Resin would make a good choice. It will effectively 'seal-in' the polyester bodyfiller prevent it from causing any problems for the release agent. You'll find that our Epoxy Coating Resin makes a very tough shell indeed but be prepared for some more flatting and polishing after you apply the coating resin because, although it will cure with a nice clean hard surface, it will have some ripple in that you'll need to flat back and then polish.

Similarly I may make the same pattern in machined acrylic. However, I would still need to use P38 filler to fill in gaps and so I wandered if I still need a sealing coat on top or if just a wax would do? In the case that I still need a surface coat do you think that the same Epoxy Coating Resin would work well here?

Yes, I'd say the Epoxy Coating Resin would be the way to go if you coated an acrylic pattern in polyester bodyfiller, for the same reason as above. As an aside, I'm not sure how well the polyester filler will stick to the acrylic but if it's just for a few releases it might be OK, particularly if you have a hard coat of epoxy over the top.

I hope this helps and look forward to working with you.

Best regards, Matt


Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Hi Matt

Thanks alot for your advice - this is much appreciated!

Its good to hear about the other options and I particularly like the idea of the release film as a designer trying out many prototypes fast. So I will get some supplies in and give them ago.

Cheers,
Kristoff

You're welcome. I forgot to add a link to the Unperforated Release Film and also you might be interested to take a look at this video where you can see the release film being pulled tight over a repair. It's not the way you'll be using it (you'll be wrapping the part and then laimating over the top of the film) but it does show you how you can pull the film tight:

http://youtu.be/Xm2Ezo70vFI?t=6m39s - This link will jump you right in at the part with the film.

I hope it goes well.

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales