This is explained on our dedicated mould information page. Put simply, there is no shrinkage from master to mould with a cold silicone mould. Generally, shrinkage is approx. 1.5/2.0% from master to vulcanised mould, then a further 1.5% from mould to casting. There is no shrinkage from master to mould if a cold mould is used. Pink no-shrink moulds are an alternative to a cold mould if the master pattern is metal. There will always be casting shrinkage regardless of mould.