Liquid Latex Rubber (dipping rubber)
Latex is a natural air drying liquid rubber easily used to produce thin skinned, highly elastic moulds.
A former (original model) is simply dipped into the liquid latex. A thin film of latex will cling to the former, and dipping is repeated until a skin of the required thickness is built up.
For one off or limited production runs, formers can be made from glass, aluminium, glazed porcelain, polyester resin or plaster. Copper, brass, bronze or ferrous formers should not be used as the metals impair the rubber (for the same reason, latex should not be stored in containers made from these materials).
Latex should be stored in airtight containers. A sheet of polythene floated on the surface will prevent the latex skinning.
Immerse the former slowly in the latex, making sure the liquid flows in all dents and undercuts, then remove the former and allow to dry for a few minutes, then repeat the process five or six times to build up a significant thickness.
After dipping, the mould should be left to dry thoroughly before removing from the former. Drying will take about 24 hours at 24oC, longer at lower temperatures. Higher temperatures should not be used if over dried, the latex loses its elasticity. Once dry, the mould should be rinsed in diluted washing- up liquid, then peeled from the former. Before turning back the right way, dust the mould with French chalk (talc).
Untreated plaster formers should be thoroughly dried before re-use, non-porous formers can be reused immediately.
