What Can I Use To Make Keys In My Two-Part Mould?

Keys are simply shapes on the parting line surface of the mould that nest into each other to align the different parts of the mould.

A groove shape can be carved into a clay parting surface prior to pouring the first section of the mould. Then the first poured section will have the reverse shape (a tongue) on the rubber. When the mating part of the mould is poured the groove will be in that half.

As shown below, marbles pushed half way into a clay parting surface before pouring also create great keys.

TIP: Neill’s Materials sell useful bags of 10x various sized Mould Keys. These polyurethane resin keys will self release from most mould making materials and are reusable.

Original Source: Polytek Development Corp.