In this instructable I will show how to make a simple silicone matrix/cavity mould, single piece, the simplest form of matrix mould, it is possible to do multipart matrix moulds but I wont be covering that in this instructable.

I needed to make a silicone mould of a part and I didn't want to use a load of silicone by doing a block mould for such a large part so I thought I would give matrix moulding a go.

there are a few methods for creating a thin silicone mould with a fibreglass jacket, one method is to add a thickener to the silicone paint it on until you think its thick enough then let it set, and build a fibreglass jacket on it. problem with this method is that you can end up with thin spots on silicone mould which would be prone to tearing.

A matrix mould allows a uniform thickness of mould over the whole part you want to cast and it uses significantly less silicone than a block mould so it works out slightly cheaper. the down side is that it requires a little more time for the setup.

This kind of mould is also referred to as a cavity mould as you are creating a cavity between the master (the part you want to mould) and the jacket.

Step 1: Equipment and Materials

you will need the following materials and equipment, some are optional and are noted as such. and a suitable master to make a mould of, I used a MDF elbow gimble master from my life size ED-209 project


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Condensation Cure Silicone - You could use and mold making silicone but I am using condensation cure Shore 25

Polyester laminating resin - for fibre glassing

Fibreglass Matt - I used 450 gsm its cheaper but you use more resin, you could use 300 gsm matt

Foil Tape - optional

M6 Bolts - 6mm bolts

M6 Penny Washers

M6 Wing Nuts

A thick disposable board

Equipment and consumables

Latex Gloves

Tongue depressors - for mixing resin

2" GRP Brush - this is a brush that can be used with the fibre glassing resin, normally its a natural fibre brush as they wont melt with the resin.

Paint mixing cups 600ml

Counter top food mixer - Optional, I used it to mix the silicone but you can mix it by hand.

Vacuum Chamber with Pump - Optional, I used this to degas the silicone to help prevent surface bubbles.

Saran wrap / Cling Film / Pallet wrap

Clear Straws

WED Clay or Oil Based Modeling clay

Blue PVA Mould Release.

Vaseline / Petroleum Jelly

Silicone mould release

Old clothes / overalls - you don't want to get resin on good clothes

Retractable Knife

A drill

A drill bit the same size as the bolts.

A drill bit the same size as the straws, this happened to be the same size as my bolts so I only needed one.

<p>Great instructable! Very thorough instruction and detailed steps, including excellent illustrative photos of the whole process. Thank you!! </p>
No problem at all, if it helps anyone understanding how to make their own matrix mould then thats great.

About This Instructable




Bio: One day I shall own a Delorean.
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