bathroom silicon sealer mould for resin casting?

[Zipadee Doodar]

is it possible to use bathroom silicon sealer to make a mould for use in resin casting? Anyone done this at all?

ZD

[Mary Fisher]

Yes, I have. It's possible but you mustn't be in a hurry, it takes a VERY l-o-n-g time to cure in any mass.

You'd be better buying the properly designed silicone moulding medium, a two-part substance which will be able to be used for very many castings even at very high temperatures. Go to

If you only want to use your mould for one or a few castings try the re-meltable vinyl moulding medium, called Gelflex or Vynamould. Your local craft shop probably has that, if not contact Tiranti. the definition isn't as good as the silicone medium but it's pretty good.

Mary

[Ian Stirling]

Mixing a little of an appropriate alkali in works well. I've tried wet bicarbonate of soda, and as expected, you get a slightly foamed result.

Painted on one layer of caulk using a stiff brush, let it set normally, then piled on the rest.

Alternatively, chalk powder (again wet, to supply moisture for cure) may work too.

(used for casting small cement fish)

[Jerry Built]

Yes, you can. It is best to use a thinnish coat of silicone rubber and then Plaster of Paris or whatever to support the rubber (make sure the outside of the rubber gives a good key to the plaster).

You can also cast small lead objects in silicone rubber moulds (which must be absolutely dry).

J.B.

[Simon]

you could ..... but why would you want to? it would be a rather time consuming endeavour compared to buying some 2 part RTV with a thixotropic additive and using that ... the thought of building up thin layers and having to wait until each one has set before adding the next strikes me as a rather tedious way of going about it. you should have a mould ready in say 7 days? .. that you could be using the same day as moulding if you used a 2 part RTV.