I have a part from which I want to take a mould - it's around 50cm long by 46cm wide at the widest point.  I'm unsure as to whether the ready mixed epoxy fibre kit would be best or the uni mould kit, and which size to use if the former.  Guidance on this would be great.

It's a small motorcycle fairing and is curved so part of it touches the board and the top is about 6 inches of the board.  I've watched the video and saw that when making a small part, modelling clay is used to created flanges. I could do that with the part it would just need a fair amount of it (46cm across by about 15cm high) to bring the moulding cloth/putty down to the board. Is that the best thing to do? Or better to cut out sign board and make flanges that way? 

Hi Mike,

Just been through all the grits to 1200 - is it best to polish it and if so with what type of polish? Or just put on mould wax then a few layers of easy lease then do the uni moulding ? When the part comes out, then wet sand and polish the mould?

Always get your pattern as perfect as you can, it's far better and far easier to get a perfect finish on a male pattern than it is on a female mould. Female moulds are, by their nature, concave which is much harder to flat and polish than a convex shape. Also, it's nicer to not be rubbing bag the gelcoat on the mould surface if you can avoid it.

As for which polish, T-Cut is really not used at all in the composites industry and has an oily/solvent residue which doesn't work well with release agents. Also, it's too fine for most cutting.

We sell Mirka Polarshine which is a great cutting compound. T10 is our best seller because it can be used on its own, or you can go for a C20 (Coarse 20) and then an F05 (Fine 05). Other brands are Kovax Modente paste or Faracla Profile, both of which are excellent too.

Or would it just be better for the finished result to get it painted in 2 pack polyurethane paint?

Two-pack paint is great for a pattern surface but if you've got a polyester gelcoat surfaces pattern and you're using Unimould to make your moulds (which is a vinylester gelcoat) then there's no need to change to a paint finish. Polyester polishes up really well so I'd just polish up the polyester mould, clean it off, release prep it and pull your moulds!

Lastly, I'm still up in the air about how many layers of reinforcement to use.

I'd say probably two layers of carbon either side of the coremat but if you're in doubt I think it would be a good idea to make up a 'token' (a test sample) that you could bent and break to destruction so that you can know with confidence what layup is right. Start with 2 carbon either side of the coremat and just lay up a small sample. Cure it off and see how it feels. It's a good way to test out your other methods as well and ensure everything is right before the main event.

All the best, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales