Silicone Mouldmaking Rubber

Addition and Condensation cured rubbers for making moulds

Silicone Mould making rubbers have been in use as a mould making material for many years. These Silicone Rubber Materials have natural properties which make them ideally suited for use as a moulding medium for part reproduction as well as use for products in their own right.

General Features of Silicone Rubber

Fine detailed reproduction of most surfaces
Excellent self release properties (use of release agents not normally required)
Durable
Good tear strength and elongation
Low shrinkage
Easy and Simple to use

There are 2 different types of silicone rubbers:

Addition cure systems which use platinum based catalyst.
Condensation cure systems which use a tin based catalyst Silicone Rubbers cured with either system have very similar properties but there are some differences which should be considered when using or making moulds from either type of Silicone Rubber.

Silicone rubber key differences:

Addition Cure Silicone (Platinum Based) POLYMECH PROTO Series

Low shrinkage, below 0.1%
Marginally higher tensile strength
Slightly tougher rubber
Need for careful and accurate mixing
Platinum catalyst can be chemically contaminated *
Good abrasion resistance
Can be accelerated using heat
Tolerant to the addition of silicone fluid as a softener

Condensation Cure Silicone (Tin Based) POLYMOULD Series

Lower costs
Wider range of properties available
Less sensitive to mix ratio errors
Easy to use with thixotropic agents to produce a brushable silicone rubber product.
Cannot be Heat Accelerated to speed up cure
Fast catalysts available to speed up cure
Mixing of grades possible to achieve desired hardness