Cracks on the Sides of Polymer Pieces

Sometimes, when you use 3-D printed cutters to make polymer clay shapes you may notice horizontal cracks on the sides of the pieces, almost like they’re separating into layers. Sort of like a flaky croissant! Since these cracks are not usually noticed until after baking, it’s easy to assume they are caused by the baking process. No, these cracks on the sides of your polymer clay pieces are something else entirely. Here’s what you need to know about these cracks on the sides of your polymer clay pieces.

Graphic that reads, "Cracks on the Sides of Polymer Pieces" with an image of pink pearl earrings.

About Cracks on the Sides of Clay Pieces

Here are some things to know:

☝️These cracks were there before you baked the clay, but may have expanded during baking like a flaky croissant. They’re not caused by baking.

☝️The most common cause is using blunt cutters that smash the clay rather than cut it.

☝️It’s caused by the clay cracking instead of yielding to the pressure of a dull cutter.

☝️Fimo Professional, Cernit, and Hobby Lobby Advanced are the brands most commonly affected.

☝️This isn’t caused by poor conditioning or hard clay. It happens with soft clay at times.

☝️Use sharper cutters, but even with sharp cutters, you will see this in some clays!

☝️Try using templates and a craft knife rather than cutters.

☝️Warmer clay will crack less during cutting, so try warming your sheet slightly on a heating pad set on low.

☝️You can fix cracks by filling with a smear of the right clay color or translucent and baking again. Smooth before baking to avoid having to sand.

Notes about these earrings…

The above earrings are made with Cernit Pearl using the mica shift technique.

There is no resin or varnish. This is just 100% polymer clay that’s been sanded and buffed. If you want to know how to create this flawless, shiny finish the best resource is my Sanding and Buffing Polymer Clay course. The course also includes a bonus tutorial showing how to make the mica shift technique used to create the design on these earrings.

Sand better, not harder

Everyone loves a perfectly smooth, glassy finish, but it seems to be elusive. Does your polymer clay look scratched and rough after sanding? This course will change everything.

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