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Make two part molds with silicone mold putty

Make a small batch of silicone putty.
push original into the putty, up to the mold line.
let cure.
put in vents for air to escape and a pour hole
cover with more putty, but
will the new putty adhere to the old? How do I keep the mold pieces seperate?

also

If I want to use pewter originals, how do I prevent tin contamination of the mold?

canucksgirl5 years ago
I just helped another member with a similar question in making negative molds and suggested a product called Easy Mold (which you can find in stores like Michaels). It can be used with low melting metals. You simply mix the 2 parts and pour it into your mold. I would recommend that you encase the object that you want to mold into the silicone along with a straw (to allow you to pour in your casting material later). Then once the silicone mold has dried, use a sharp blade and cut the silicone block into 2 pieces, and you'll have a perfect, detailed mold. I've used it before and the member I helped just bought the same product and used it and was very happy with the result, so it might be worth looking into for your project. ;-)
frollard5 years ago
Pewter/Tin is not soluble in silicone, and won't leave anything behind if you use a high temperature silicone.

Check www.smooth-on.com for silicone molding materials. If you don't want the 2 halves of the mold to stick together you put a layer of release agent (usually a wax based spray) between the layers. It allows almost perfect jointing with no gap.
hardlec (author)  frollard5 years ago
I have read that putty molds don't react well, don't cure completely with tin originals.
Will paste wax (i.e. kiwi) work? Spray cans and I don't play well together.

Thanks.
paste wax should help insulate the materials...I'd still say its best to use the best material designed for the job.