How to Make a Mould for a Carbon Fibre Bonnet (or Similar Panel)

Ideally choose a panel in good condition with minimal paint blemishes or defects on the surface. The better the quality of the panel now, the better quality the mould surface will be and less need for repairs and polishing later.

Remove any parts that are not to be moulded - such as the bonnet latch. Create templates for and create the mould flanges. Gaps around the flanges can be filled using filleting wax to get a sealed gap and smooth transition to the flange.

To ensure the best possible chance of a successful release, it is wise to use 2 release agents at this point. First EasyLease is applied to the bonnet with 5 layers being applied. Secondly this is backed up with 2 layers of mould release wax

The mould for the outer skin is then made using the Uni-Mould Mould Making System. The lay up for this mould is standard for the Uni-Mould system and consists of Tooling gelcoat backed up with coupling coat and 100gsm CSM, finally finished with the Tooling resin and 4 layers of 450gsm CSM to add the backing strength to the mould

The Outer skin mould is left to fully cure before turning over the whole mould to make a start on the Inner Frame Mould.

The flange barrier material is now removed, exposing the flange of the bonnet skin mould. The Filleting wax around the outside of the flange is trimmed and neatened to ensure the same good seal between the Outer skin mould and the bonnet itself. The holes and slots on the frame underside are sealed over with Release Tape to keep the resin out and produce a smooth neat finished mould.

The entire bonnet underside is then coated in release agent just as the outer skin, with extra care taken to ensure the new flange is properly coated in release agent,

The mould making process for the inner frame is identical to that of the Outer Skin. Once complete, the mould is allowed to cure fully before it can be trimmed and demoulded.

Mark around the outer edge of the flange with a marker pen as a cutting guide. The rough edges are then cut off using a jigsaw to reveal the neat edges of the mould. Using a chisel or demoulding tool, carefully pry between the upper and lower moulds to open up a small gap, Carefully widen this gap and separate and demould the Outer Skin Mould and Inner Frame Mould from the Original bonnet.

Once demoulded, any rough edges can be tidied and the wax removed prior to inspecting the moulds for damage.

A small patch has been damaged and will need a gel coat repair. Using tools and sandpaper, the damaged material was removed and prepared for repair. A small batch of Tooling Gel Coat is mixed up with some MW1 Wax Additive Solution to avoid a tacky surface finish.

Once cured, the repair was carefully sanded flush with the surrounding area before being polished back to a high gloss.

To get a very high quality professional finish, the mould was sanded and then polished. The mould surface has very fine print through from the mould process and some small marks and blemishes from the imperfections on the original bonnet. The imperfections were removed by wet sanding the surface working through the grits from coarse to fine. It was then machine polished to give the high gloss finish.