Is Polymer Clay Porous?

People often joke that I’m like those guys on Mythbusters. I love to get to the bottom of the myths. (here’s a bunch more I’ve already busted)

Here’s a myth that I’ve heard repeated over and over for the entire 18 years that I’ve been working with polymer clay. Let’s put this one to rest!

It’s often repeated that polymer clay is porous. It is not. 

Wood, paper, and cloth are porous. Glues used on them, and paint applied to them, seep into the spaces within the material itself and are absorbed. You can’t remove glue or paint from paper. It becomes one with the paper.

Polymer clay is vinyl plastic that’s been mixed with binders and fillers (similar to chalk or talc) that allow it to act like dough or putty, (as opposed to the drippy syrup of liquid clay). Those fillers can absorb water.

So sometimes it appears that cured polymer is absorbent. But it does not have spaces into which the glues or paints can flow. Glue and paint will bond to the surface of the cured polymer, rather than being absorbed into it.

Treat polymer clay as a non-porous material.

As an aside here, a related myth that often gets repeated is something similar to this: “Polymer clay has microscopic pores where bacteria can grow, that’s why it’s not food safe.”

As is often the case with myths, this one has several misunderstandings lumped together.

  • Everything has microscopic pits, even steel. Having pits does not mean something is porous.
  • Disease-causing bacteria won’t grow in polymer clay. 
  • “Food safe” is a complex certification/classification that has to do with the suitability of a material to withstand the rigors of temperature, cleaning, and sanitation, not with porosity. Otherwise, we couldn’t have food-safe wooden cutting boards.
  • Polymer clay isn’t suitable for making food vessels for many reasons, that doesn’t mean it’s toxic and our lips should never touch items made with it. Make whistles! 
  • From pores harboring bacteria, the conversation often goes to skin contact. Polymer clay is vinyl, not poison. Yes, you can make earrings with it, even “gauges“. And no, bacteria won’t grow in those, either!

I hope this myth can now be put to rest. And I’ll be looking out for the next one to bust. It’s like whack-a-mole, though. They pop up faster than you can whack ’em down. On with the day!

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Ready to level up?

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Insiders is a supportive polymer clay learning community with live discussions, monthly discovery challenges, and a private community forum. Join us!

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