Rubber Mould Making

VULCANIZATION METHOD

Once we have received your model and a suitable compound has been decided upon, we then proceed to make your rubber mould this is done by building layers of rubber around the model with every part of the model including any hidden cavity’s carefully filled with rubber, once the model is embedded within the rubber block it is then placed into an aluminium frame to be vulcanized, the aluminium frame containing you mould is placed into a press for approximately 45mins to 1hour and heated to 150c once the mould has vulcanized it is left to cool the mould is then trimmed and the skilful procedure of cutting the mould can begin. with the use of a scalpel the mould has to be cut into two halves this is a highly skilled and intricate part of the process, location points are first cut into the mould and then our mould maker cuts down the sprue to get on the edge of the pattern he then cuts around the edge of the model, this is where the amateur mould maker can make severe errors by coming off the cutting line and hence leaving nasty parting lines along the surface of the item once waxed, once the mould has been cut into two halves vents are applied to areas where the air could become trapped the mould is then coated with a lubricant spray and a test wax produced to see if everything is ok with your finished rubber mould.

LIQUID RUBBER METHOD

Also known as cold cure or RTV(room temperature vulcanization) this method is the only option for wax carvings, plastic, twigs etc basically anything that will not tolerate heat or compression, the model is stabilised within a u shaped aluminium frame and two plastic plates are secured on the outsides to form an airtight container, silicone base rubber is then carefully weighed out and a catalyst is the added to the base mix, the silicone is then mixed thoroughly and then is placed within a vacuum chamber to eliminate all the air from the mix, the frame/container holding the model is then carefully covered with the liquid rubber and allowed to set at room temperature.

The rubber is then cut just as before in the vulcanized method however cold cure/rtv requires more care than vulcanized compounds as the silicone is not forgiving, because of the nature of silicone rubber the rubber is easier to tear in thin sections than the vulcanised compounds and so extra care is taken and a slightly different cutting technique also applied to allow the wax to release from the mould easy.