Silicone Rubber

How to Guide

Refers to Moulding a statue 800 X 300 X 150

Pot life is 1 hour so no hurry to mix and use. This decreases with temp and humidity but pot life independent of catalyst load.

De-gassing is strongly recommended to improve surface. For De-gassing you need to allow at least 4 X the volume of product being De-gassed. ie. 1 Litre of silicone needs to be in a container at least 4 litres volume.

It is Ok to pour a mould in several pours as long as everything is done within the 1 hour pot life approximately.

Mix thoroughly, it is recommended to use a paint stirrer for at least 5 minutes. Use a fresh container between batches, however, containers can be cleaned for reuse later - silicone can be peeled off or cleaned off with acetone.

Catalyst added at 5% - more will make the silicone brittle, less will impair curing.

Two most common ways of making a mould are as follows;

1. Use thixotropic additive and coat the object, back with a fibreglass jacket for support.

2. Make a wooden MDF moulding box

If you want this to be self supporting then give say 400mm clearance around the sides between the object and the moulding box. If you re-use the box as the backing then you can get away with 12-15mm clearance.

With a tall statue, cast mould vertically with the statue standing on it's base. Fill with silicone and leave for 6-12 hours. Disassemble box and remove mould. Split down the side only enough to remove the statue. Turn upside down and place back in the box for casting. Vegetable oil or mould release agent will prolong the life of the mould. Slow curing concrete's will  give off less heat and concretes with less lime may prolong mould life. Expected life of mould is 20-100 pulls depending upon shape, concrete, mould release, technique and general care taken by moulder.

Example below is of a 2 piece mould.

MDF box used as backing and half filled with clay. Object inserted into clay (some clay would need removing depending upon object. Marbles inserted into clay for location pegs. Silicone poured onto object and clay. After Silicone has cured reverse procedure and pour silicone onto silicone half with object still in place and location marbles removed and remove any clay residue. Use mould release before pouring of silicone..

Available Kit sizes: 1 Kg, 4 Kg, 20 Kg