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Matt asks:

I’m interested in making a silicone mold, and I’m wondering what sorts of things the silicone will stick to and what sorts of precautions to take to prevent it from sticking? I’m making a mold of a plastic figurine.

Well, you have to assume it will stick to anything. If you’re using Polytek PlatSil or TinSil, you’ll want to use a non-silicone based mold release (like PolEase 2500), and spray shellac will work in a pinch. SIlicone sticks to itself, too, so be sure to coat the different pieces of your mold in the release agent before pouring multiple parts. When in doubt, give the folks at Polytek a call; they’re really helpful on the phone and will work with your specific project to make sure you’re using the right materials and processes.

If you’re unfamiliar with moldmaking in general, check out our primer in MAKE, Vol. 08 by Mythbuster Adam Savage. You can preview the article in the Digital Edition.

If you have a question for Ask MAKE, send me an email at or tweet at us!

Becky Stern

Becky Stern

Becky Stern is director of wearable electronics at Adafruit Industries. Her personal site:

  • MadSpark

    My experience with the Smooth-On platinum cure silicones is that they don’t stick to ANYTHING — except silicone or, if you think about it this makes sense, glass.

    Now, it will wrap around fine details (like hairs) and exert a (sometimes considerable) pull on them, but that’s a mechanical locking and not a chemical sticking.

    If you have a porous object, seal it, to avoid this mechanical lock.


    I read this article in my Make Magazine and it made me want to get started on my Tap Handles for my home brew beer! I have a custom wooden tap handle for my home brew beer and I want to make several copies in a hard plastic like Resin. The article does not cover working with Resin or hard plastics to cast the mold nor does it cover making such large pieces as I would need. (12″x6″x6″), Also, I am looking into painting the mold and then casting the tap handle to have it pop out pre painted!

    If anyone has experience casting hard plastics, larger molds, or in mold painting please contact me at Thanks!

  • Dave Stewart

    I have used McLube 1700 & McLube 1711 for silicone for years. It works outstanding.

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