Mini Tutorial: Thixotropic Silicone Moulding

Fancy making your own moulds, or maybe you have been making them with Siligum- a two part clay-like mixture? Silicone can be quite expensive but not as expensive as Siligum, but sometimes you need it’s properties for making small moulds, which help it to last longer- there’s no pouring it into a large container and having too much waste around the edge! Here’s how to make your own version of Siligum, which can be used for gravity defying mould making (maybe you want to capute a detail on a ceiling rose?!) and repairing silicone moulds too!

NOTES! This has the consistency of cake frosting, so you will need a mixing cup and stick. This only works with addition cure silicones- these are the most common types where you add a 2% catalyst to the silicone liquid. Thixotropic Solution is available at all good silicone suppliers, I bought mine from www.tomps.com

1) Pour your silicone into a cup and add 2% volume catalyst (instructions in my book) with the same amount of thixotropic solution (2%). Mix really well until the colour is consistent. I used a fast catalyst (red), but it is also available in slower curing varieties such as blue. I find red works best for this technique.

2) Now you have a thick, gloopy mix! Spread it like a thick layer of peanut butter on the model you want to make a mould of. You can also use it on your skin to make body part moulds though do be aware you will have to stay still for quite a while! This is really economical moulding as you don’t need to put your model into a container. Make sure your mould walls are pretty thick though, about 1cm should give you a long lasting mould.

3) Leave to set for a few hours (half an hour to an hour should be enough for skin moulds) and if it is no longer wet and sticky, then you can peel it away from your model, and there you have it!

You can use these for resin, polymer clay, silver clay, allsorts really! I now plan to test out the flexible additive for polyester resin today and see what happens!

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