RTV silicone rubber for plaster crown moulding

First of all you must prepare a perfect original crown model, followed by cleaning work with detergent and drying it with an air gun. Then a layer of release agent is required for we need to demould in the later operation and we must make sure that the RTV silicone mold will not be broken by the demoulding process. We suppose the plaster crown is in a medium size, so we had better choose the brushing molding method rather than pouring molding method. Moreover, maybe we should make a multiple-pieces mould which is collapsible and convenient.It is important to choose the right parting mold line, normally the mold should be made in two pieces or multi-pieces for complex plaster crown. Evenly brush the first layer of RTV silicone rubber on the surface of the model. Normally the first layer RTV silicone rubber is brushed thinly to cover the model, so it should not be too thick. After brushing the first layer of RTV silicone rubber, put the model into the vacuum container, then deflate and take out the plaster crown model. Totally four layers of RTV silicone rubber for plaster crown moulding is OK. To make the silicone mold stable, the out protective resin shell is essential.