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Elvenwork Forum

This forum has been a way to provide a public exchange of questions and answers for polymer clay sculptors. But, as I said in my final post, there comes a time when all things must end. That doesn't mean the forum used as an archive has nothing to offer. Indeed it is still loaded with questions and answers that remain relevant and which are searchable! For that reason, I'm keeping it available, though no new posts can be added. If after searching the forum your question isn't addressed, Join me on to ask it. As always, you'll find me there as Katherine Dewey. Hope to see you there. --  Katherine

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What happens when you bake polymer clay

No chemical reactions transpire when you bake polymer clay. The transformation of one set of chemicals into another (got that from Wikipedia) does not take place. Polymerization, the linking of two or more monomers (a simple compound whose molecules can join together to form polymers) does not occur. PVC, the component that gives polymer clay its name is
already a polymer. It's been ground into a fine powder, but the polymer chains are there. You gotta think molecular to understand how small they are. So, what's happening when you bake the clay? It's called fusing, and that's kind of like "sintering", the making of a solid by heating a powdered compound just below its melting point (another string of words from Wikipedia). If you've ever held a warm Xerox in your hands, used a heat gun on embossing powders or messed around with ceramics, you've sintered something. And, you may have noticed these sintered powders have expanded a bit as they melted and fused together.

Wait -- polymer clay is not a powder, is it? Well, with rare exception (gel stabilizers that prevent chain scission, the breakdown of polymer chains due to heat), polymer clay is a compound of dry powders (PVC particles, pigments, bulking agents) suspended in a liquid plasticizer. The plasticizer gives the clay its plasticity before baking, and, because plasticizers work by embedding themselves between the chains of polymers, spacing them apart, they're ideal as a suspension agent for plastics manufacture, including polymer clay. When you bake polymer clay, those porous PVC particles (infused with and suspended with plasticizer) swell and fuse together. They kinda sinter, just like Xerox toner or ceramic glazes or embossing powders. It's that simple.

Re: What happens when you bake polymer clay

Thank you Katherine, I hope we can both continue to probe the depths of the Polymer Clay mysteries and find ways to better understand and make improvements to this wonderful material.

Re: What happens when you bake polymer clay

Can you post or email me a link to where on wikipedia you found this? I am having trouble locating it. Thanks in advance for any consideration.