Fibreglass Mould making....

The normal advice is to avoid anything containing silicone - I don't know the reason for this. Theoretically you should be able to use copius amounts of furniture polish though. Why not trial a small area first?

I've just bought a 400g tin of the proper stuff off the bay for £12.50 delivered, so yes, it is pretty expensive just for the one job.

PVA does the same job as release wax. Just coat the part in PVA, do your layup and when dry, part the FRP from the trans tunnel - the PVA will allow it to release, and will also usually peel away from the gelcoat - if its being stubborn then some warm water will disolve it. I would use PVA over wax if I wanted to be 100% certain that the mould will seperate rom the plug.

Wax on the mould before PVA will help the parts seperate if the draught angles are quite steep, but don't think you will have this issue with a transmission tunnel.

East Coast fibreglass carry everything and their online site is pretty good.

What was the website where John got all his stuff i've forgotten it.

Matt

Thanks Guys, all useful stuff.
Completely new to mould making but quite excited by it TBH.
The east Coast supplies site looks good, ordered my supplies last week though.
Just out of interest, as an alternative to standard matting, could the carbon/kevlar combi matting be used to the same effect in fewer layers, because it has a higher strength?
I have gone for 450gsm matting, but the carbon/kevlar stuff is available in 180gsm.
If I used that instead, does that mean I could make just as strong a mould, at considerable weight saving?

ooooh - my poor flexible friend..... bits for the GTT6 will be sorted asap.
Wonder if I can knock up a pit shape while the garage floor is mullered
;D 'just drop that in fellas thanks'

I too read PVA was the way to go previous users have had better experience on seperation.... although I'm also a newb - so will probably muller it no matter what

Good luck - photo's on how it comes out... or step by step guide even? pretty please?

Cant say I don’t pay attention!



But if separation is a big concern, I would personally do a lay up with PVA, take a mould, then make a part from that mould – fill sand where required and then take another mould from the part, and then make another part from the perfected mould – long winded but would save the “oh flaps I have just bonded a wad of fibreglass to something and I cant remove it moments!”

Trust me, I used wax on the first time I tried to make a mould of one of my velocity stacks – hoping for a pristine finish and they simply wouldn’t separate! PVA means they will always come apart. TBH on the subsequent mould I did using PVA any imperfections in the finish are tiny – even if you were knocking out panels I don’t think anyone would notice.

Those Make up sponges John used gave a good even finish though!

Guessing you could also spray PVA as well to ensure it goes on nice and smooth. When I am not messing with painting the car I am also going to see if Its possible to spray gelcoat with a normal gun and a big nozzle – for a good even gelcoat thickness.




If you plan to use Kevlar / Carbon then you will want Epoxy resin. Whilst you can use Polyester with Kev / Carb its quite brittle and not as strong. Carbon and Kevlar will always be stronger than FRP of an equivalent thickness. But you wouldn’t want to waste Carbon / Kevlar on making a mould – use chop mat for the mould then make the plug with the material you want as the finished product.

450gsm chop mat sounds pretty thick though, cant remember what I normally use.

FYI to avoid any mess etc – mask off the area’s you don’t want the FRP to stick to with masking tape / parcel tape. Resin won’t stick to the tape. Just means you can make a nice neat mould without the resin running out all over your floor pan. If you don’t have PVA or Wax you can use tape as a release agent if needed.

Another question.....sorry Guys! This may actually belong in the Daft question amnesty...
Because the part I am making is a transmission tunnel cover, that will then be covered in tunnel heat shield, and then trimmed, the finish is not critical.
Could I actually use the mould itself? I appreciate it will be a few mm larger than the plug itself, but that won't present a problem.
Or, am I just being a lazy curse word!?

Don't know but since you have to make the mould anyway, why not try and se. If it works it's a cover, if it doesn't it's a mould.

Oh, is the transmission cover a structural element in your car?

Robinji

At some point I'm going to make a bonnet out of plain old glass/polyester but am wondering about reinforcing the hinge and bonnet pin area with some carbon or kevlar. Could you advise the best way to do this please?

I.e. what surface area from the bolting point, what gsm, weave, and number of layers would you use; would it be carbon or kevlar, and would it be embedded with another layer of glass or the last layer in the lay-up?

Also you mention aramid in the area of the gearbox cover by the flywheel, again, what qualities and layup would you recommend?
(sorry ofr a bit of a hijack)
Ta
Madmog

Cheers