I love polymer clay and I love silicone mold putty. In fact I recently explored the difference between two main brands of silicone mold putty, Easy Mold and Amazing Mold Putty. And if you work with polymer clay, sooner or later you begin to get curious about using silicone mold putty and begin to think about how it works with polymer clay. And if you can use them together. Here are two ways that you can use polymer clay with silicone mold putty.
Using Silicone Molds to Create a Polymer Clay Object
You can use silicone mold putty to create a mold or texture sheet from some object or texture that you want to duplicate. For instance you have a small figurine that you want to duplicate in polymer clay. You would use the mold putty to create a mold from the figurine. Then put polymer clay into the cured silicone mold to create a polymer duplicate of your figurine.
You can learn more about using silicone molds with polymer clay in my article here. I show you how to fill the molds, get a good impression, and de-mold the cast without distortion.
Making Silicone Molds from a Polymer Clay Object
The second way is to make an item from polymer clay and then create a mold from that polymer clay object. You would then use the silicone mold to make more polymer clay objects or you could use the mold with other materials like chocolate, wax, resin, soap, or even low melt metal.
Seems simple enough and quite straightforward, right? I thought so too. But then a reader, George Cheech, told me that he had problems with mold putty curing when it was used on Kato Polyclay. I’d never heard of that before, so I did a quick test with some clay that I had sitting around. And sure enough, Amazing Mold Putty did not fully cure when it was molded over Kato Polyclay. And that made me think. Does cure inhibition happen with all mold putties when used with uncured polymer clay? What about cured polymer clay? And does the brand of polymer clay make a difference? Well you know me. I had to find out.
Cure Inhibition of Silicone Mold Putty on Polymer Clay
I cut out a circle of every brand of polymer clay that I had on hand and arranged them on a ceramic tile. I used Sculpey Original, Super Sculpey, Sculpey III, Premo, Souffle, Kato Polyclay, Cernit, Fimo Soft, and Pardo. All colors tested were white except for Super Sculpey (which is a pinkish-beige color) and the Cernit and Pardo which I only had in translucent. I then mixed up some Amazing Mold Putty and some Easy Mold and put a little ball of the uncured mold putty on the uncured polymer clay circle. Then I waited for them to cure (about 30 minutes or a bit more). I ran the same test on cured circles of the same polymer clays.
|Unbaked Clay||Baked Clay|
- AMP – Amazing Mold Putty
- EM – Easy Mold
- OK – Complete cure of mold putty
- X – Cure inhibited
- sticks – polymer clay stuck to the cured mold putty
- soft – mold putty was soft, suggesting an incomplete cure
- pits – mold putty cured with pits in the surface
According to my test, if you’re going to make a silicone mold from polymer clay it will work best if the clay is fully cured first. Making a silicone mold from unbaked polymer clay did not work well with most clays and with both brands of silicone mold putty that I tested. Creating a mold from Kato Polyclay and Cernit, even when the polymer clay is baked first, did not result in a complete cure of Amazing Mold Putty.
In short, make your silicone molds from baked polymer clay. And if you’re going to use Cernit or Kato Polyclay, you must not only bake the clay first but you need to use Easy Mold instead of Amazing Mold Putty.
I only tested two brands of silicone mold putty and there are many dozens of brands of this material, each with their own characteristics. I can’t make any judgement about the cure inhibition of those brands. But my test does suggest caution when using Kato or Cernit. And that you should not expect good results when making a mold from uncured or raw polymer clay. Always test your materials first before devoting hours of time and effort on a project only to have it ruined by incompatibility.
I see no reason to expect that cured silicone molds will cause any softness or problems when used to create a polymer clay cast. So feel free to use mold putty for making molds and texture sheets that you will use with polymer clay. This is a time-tested method and works very well.
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