Hi there,

Silicone are normally self-releasing so the dont need any release agent, except when you want to pull a silicone part out of a silicone mould

Matthieu Libeert
Founder MAT2 Composites X Sports
website: www.mat2composites.com

Hi Emma,

Like matthew says, the only thing silicone really sticks to is silicone and so, if you want to create a two part silicone mould in the way that you're desribing (pouring the two haves at two different times) then you would need a release agent of some description. The most common would be petroleum jelly (Vaseline) wiped over the surface of the 'seam' line.

• It's quicker (only one pouring operation)
• It doesn't require a release agent
• It doesn't determine which way you need to orient the pattern when pouring the silicone mould.
• The registration of the zig-zag cut pattern works very well to register the two halves of the mould together when you're actually making your castings.

I hope this answers your question regarding the release agent and also give you some ideas for making the split mould without the need for a release agent.

Best regards, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Sorry to be stupid, but seam line? You mean don't apply it to the first half of the silicone that is set, put it on the model? one pour sounds good.

Hi Emma,

Yes, I do mean apply it to the first half of the cured silicone (if you decide to do it in two pours). The way you often see it done (which as I explained we often don't favour) is to put your model in your setup box lying on its side. You then pour silicone around it up to about halfway (where the split will be in your mould). You then let that silicone cure. When it has cured you apply the vaseline to the exposed surface of silicone (this will be flat as a mill pond all the way around your model) so that the new half of the silicone mould won't stick to the first half. You then pour your second half. This should mean that once the second half has cured to two halves can be separated along this seam line and both will peel away from the model.

I hope this makes it clearer.

Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales