Plaster is an inexpensive and interesting material toexperiment with as it affords the modelmaker theopportunity to produce model bases and components thatincorporate topography and textures during the castingprocess. It may then be worked on further using knives,sandpaper or paints depending on the desired finish. This method has an almost limitless range of possibilities but it isuseful to have an idea of the intended application in termsof scale and size of the surface and component to be cast.
1.Using a container or custom made mouldformer, fix the master model centrally in place.The size of the container used should reflectthe strength required for the mould. In this casethe component will be small but rigid so 1-2cmwalls should be more than enough to supportthe cast without distortion.
2.Following the manufacturer’s instructions,thoroughly mix the silicone and catalyst whilsttrying to reduce the amount of air mixed in. Ifyou have access to a vacuum chamber use thisto get out as many air pockets as possible.
3.Pouring the silicone in a thin stream at a steadypace will help to reduce the chance of bubblesin the mould. Allow the mould to cure for themanufacturer’s specified time. Once cured,remove the silicone mould from the formertaking care not to damage the master model incase you should need to re-pour the mould.
4.Mix plaster to the manufacturer’s instructionsaiming to achieve a single-cream-likeconsistency. A good guide to mixing is toadd powdered plaster to water until ‘islands’of plaster begin to form at which point beginmixing to remove any lumps. Pour into thesilicone mould in the same manner as themould pouring process.
5. Allow the plaster to set and carefully remove thecast from the mould. The advantage of usinga silicone mould is in its flexibility, which helpsprevent any damage to fragile casts and aidsremoval.
6.The finished cast can be used for a variety ofuses such as exploring façade detail or as acomponent in a larger model.