Tin Cure Silicone Mould Rubber — Condensation Cure RTV

Tin cure silicone cures through a condensation reaction that releases a small amount of alcohol as a by-product. That by-product is the reason the rubber shrinks slightly as it cures and continues to age over time. In exchange, tin cure is far more tolerant of contamination than platinum cure: it will normally cure against sulphur clays, latex, unsealed wood, plaster residue and other surfaces that inhibit addition-cure systems.

It is the default for concrete and cast stone production, where moulds are abraded, wetted and cleaned constantly, and where absolute dimensional precision matters less than cost per mould. It is also the safer choice for taking a first mould from an unknown or dirty master. It is not the right choice for high-precision resin tooling or where long shelf life of the finished mould is critical.

Choose tin cure for tolerance, cost and casting plaster or concrete. Choose platinum cure for dimensional accuracy, negligible shrinkage, longer mould library life and food-contact or skin-contact grades. Tin cure moulds have a finite useful life and gradually stiffen; platinum cure moulds keep their properties far longer but will fail to cure entirely if the master is contaminated.

Base and catalyst are weighed accurately, mixed thoroughly including the container walls, de-aired where equipment allows and poured in a thin stream from a height into the lowest point of the mould box so air is drawn out. Masters are sealed and released. Cure times shift with temperature and catalyst level, and the supplier's stated ratio for the grade supplied always governs.

Working properties are configurable options within this canonical product, not separate products. Depending on the family, that can include grade, viscosity, mix ratio, pot life and demould time, hardness, colour, particle size or fibre length, and pack format. No configuration is presented as stocked or approved until it is confirmed against the supplier's technical data for the exact material offered. Supplier grade names, factory codes and manufacturer brands are not published here.

Send the casting material, part size and geometry, the level of undercut and texture, the number of castings you expect per mould, and your preferred pour or brush application.