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How to perform Slip Casting of Latex Rubber

latex-rubberSlip casting of latex rubber will provide a rapid build of rubber and give a mould that is of more uniform thickness. This provides a more aesthetically pleasing rubber product. There are no brush marks to spoil the appearance.


The ideal method for slush (slip) casting of latex is to start with a completely dry plaster mould or pattern. Other types of stone tend to be less porous and therefore absorb less moisture from the latex rubber. Non-porous (i.e. silicone or urethane) will work, however the result will be very poor unless a slightly different technique is used. Brush or dip latex will both work, however the thinner dip grade will release the bubbles much faster.


1. Fill your mould to the top with latex and let sit for 30 – 45 minutes (or longer) depending on required finished thickness. 30 minutes should give at least 1mm dried film thickness.


2. Pour the un-coagulated latex back into the original container for re-use. A wet film of approximately 2mm will remain gelled on the inner face of the mould.


3. Leave the mould to drain and even out the coating.


4. Dry this coating at room temp for at least a day.


5. Fill and drain again for increased thickness.


6. Dry the coating by blowing warm air into the cavity.


7. Dust the inside face with talcum powder before attempting to de-mould the latex skin. There may be times when there is insufficient latex to fill a very large mould. The mould may be partially filled and then rolled or slushed around until the required film thickness is obtained. Take care to build up the latex as evenly as possible.


8. Pour out excess latex and dry as previously.


Non plaster moulds may be used for slip or slush casting if the mould face is treated with ‘Latex Lightning’. This is an artificial coagulant for latex. It is slushed or brushed onto the mould face and allowed a few minutes to dry. The latex will coagulate similar to when used in a mould made from plaster.