TinSil® 80-30 is a Shore A 30 durable tin-catalysed silicone usually used to make moulds of objects in order to create duplicate casts. TinSil moulds have high tear strength, good release properties and resistance to high temperatures, and excellent chemical resistance. These moulds are a great choice for casting polyesters, epoxy and polyurethane resins, polyurethane foams, plaster, waxes and many other materials.
The mix ratio is 10 parts silicone to 1 part catalyst, and care must be taken to accurately measure and mix components. Eyeballing or using a calibrated cup may be sufficient for smaller amounts, but over catalysing may reduce the mould's life and also mean you run out of catalyst! It is best to use accurate scales to measure by weight.
Before use, be sure that Parts A and B are at room temperature and that all tools are ready. Surface and air temperatures should be above 15°C (60°F) during application and for the entire curing period. If cooler, the silicone may take longer to set if warmer then it can speed everything up. If moulding porous materials such as wood or plaster, it's a good idea to seal the surface first with a sealer such as wax, petroleum jelly or car lacquer spray.
To use, measure out the quantity required into a container strong enough to withstand the mixing (a paint kettle or bucket is ideal and reusable) and mix thoroughly by hand or a mixing/stirring paddle in a drill. Take care to wipe up drips and spills as you go - work clean and work smart!
TIP: If using a vacuum chamber to degas the mixture after mixing, make sure there is sufficient space in the container to allow the material to rise during evacuation. The 80-30 silicone is smooth with a viscosity of 17000cP (similar to that of Hershey's chocolate syrup if that helps paint a picture). When under a vacuum, you may need a container up to 4 times the size of the amount mixed to accommodate the expanded volume.
Once mixed, there is a generous 45-minute pot life at room temperature which is fine for most applications. Warmer temperatures may reduce the working time so ensure everything is ready before mixing the catalyst in. If making a mould by brushing on multiple layers, allowing each layer to set before applying the next. Although set after a few hours, full cure is reached after 24 hours so ideally leave a mould overnight before opening to ensure the silicone is at full strength.
No release agent is necessary for casting most materials in TinSil moulds. For longer mould life, however, it is advisable to apply a spray release such as wax or an epoxy Parfilm. Be aware that alcohol evaporates out from newly cured silicone, and this can affect some materials cast out from it, such as Polytek Poly-Optic® 14-Series clear casting resins and polyurethane rubbers. To reduce the likelihood of any problems, once opened, it is best to put the mould in a warm, airy space for a few days if possible.
When using any products, materials or equipment, you should familiarise yourself with them and take appropriate health and safety measures to protect yourself and others around you from harm. Obtain and consult the relevant MSDS (Material Safety Data Sheet) from your supplier.