Hi I have started casting recently
I have made my moulds with CS25 condensation cure silicone.
I’m making tyres for models i make, using PX60.
After 20 casts the silicon started to lose its release ability and I started having to spray a liquid wax release agent into the mould that helps but is still not as good as I’d like. But now it’s at 50 casts and the mould is totally Dried out and air bubbles are now a problem even when degassing and putting it into a pressure pot.

I’m thinking it might have something to do with the shape of the tyres as I have other simpler shaped tyres that have 50 casts but the rubber doesn’t stick but some are starting to change colour where the rubber touches the silicone now.

Is their a certain number of cast that it can do or has it got to do with my method?

You might want to look at a rigid plastic mould or even billet tooling for that kind of quantity - assuming of course you can demould without the flex a silicone mould would make. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant