For Mould-Making:
Apply PolyCoat Sealer & Release Agent to porous (may require multiple coats depending on porosity) or non-porous models when making polyurethane and platinum-cured silicone rubber moulds (not recommended for use with liquid tin-cured silicone rubber). Since PolyCoat leaves a dry, cured silicone coating on a surface, it may be used without an additional release agent. This can be of benefit when making a polyurethane rubber mould as no residual release will transfer to the cured mould surface, from the mould-making process.
For Casting:
PolyCoat Sealer & Release Agent can also be applied to ageing Platsil and Tinsil silicone moulds to improve performance (easier demoulding) and extend their useful life. In addition, PolyCoat can be applied to firm polyurethane rubber moulds to give them a thin silicone skin on the mould face. This can allow materials such as polyurethane plastics or foams, that would ordinarily require releases, to be cast into dry polyurethane moulds at a reduced cost.
Notes:
Cure time varies between 30 minutes and 16 hours depending on temperature, humidity and porosity of the model. Ensure that PolyCoat has completely cured before applying liquid rubber or plastic. Very porous surfaces may require multiple coats of PolyCoat, applied ~15-20 minutes apart. Care should be taken to adequately seal the surface, but not over-apply; as with other sealers, surface details on the model can be lost when a sealer is over-applied. When brushing, be careful not to leave brush marks on the surface as the PolyCoat begins to gel. One common technique used when either brushing or spraying is to apply the PolyCoat then flip the master over to allow excess to run off. This leaves a thin coating behind and helps to eliminate brush marks or surface defects. Do not use PolyCoat to seal plaster. Gypsum models tend to aggressively wick the solvent into pores and the curing process can be slow or incomplete, leaving some residual solvent behind, which may interfere with the cure of certain rubbers.
