Have you spent hours or even days on a polymer clay project only to find that it has suffered small cracks or breakage during baking? Cracking is almost always caused by insufficient curing or by baking a sculpture with uneven thicknesses throughout. To ensure you have a consistent thickness in your piece, we recommend “bulking out” with foil or creating an armature from Super Sculpey UltraLight™. It is also very important to adhere to proper baking times and temperatures. Using an oven thermometer is the most accurate way to make sure your oven is heated to the exact temperature.

When your sculpture does crack, there are several ways to repair the polymer clay. Read on to discover ways you can fix broken clay creations — and even prevent them in the first place! 

How to Fix Broken Polymer Clay Pieces

While it is tempting to add new clay to your creations and rebake them, this may not have the desired results — cured and uncured clays will not meld with each other. In fact, trying to fill cracks with new clay often causes them to widen. 

If your piece has suffered a break, you may be able to save your clay project with some carefully placed glue and a paint touch-up. 

How to Fix Cracks in Polymer Clay: Adding Clay Dust to Hardened Pieces 

Cracks in the surface of a project can be frustrating, but there are some no-bake ways to save your finish. If the completed piece is destined for paint, mix some two-part plumber's putty and spread it smoothly into the cracks. This epoxy will air-harden in just a few minutes, and you can sand and paint the repaired piece once it's fully set. 

Already happy with your Sculpey® color? Take a small piece of baked clay in the same shade and use a rasp or grater to make clay "sawdust." Then, mix your colored dust with a clear, air-hardening epoxy glue and fill the cracks. 

How to Prevent Polymer Clay From Breaking or Cracking 

Variation in thickness is one of the most common reasons clay experiences cracks or breakage. To ensure you maintain sufficient compactness so the piece can cure properly, try:

  • Creating an armature from Sculpey® UltraLight™ or adding crushed aluminum foil as bulk to keep the clay layer consistent. 
  • Using an oven thermometer to make sure your home oven is heated to the recommended temperature. 
  • Ensuring baked pieces of polymer clay are not exposed to significant humidity or temperature changes.
  • Working in some Sculpey® Clay Softener before baking if you are working with a very thin clay layer — the increased flexibility will help keep it stable.
  • Using a type of support under the polymer clay piece before placing it in the oven to bake. Extended or raised portions of the clay can sag or crack when heated. Supports you can use under the clay to keep it in place during baking include crumpled aluminum foil, crumpled up tissue paper or paper towels, glass bowls, fiberfill, wire supports or wooden dowels. 

Work With Sculpey® for Premium Clay and Artistic Expertise

Still have questions about how to repair cracks in polymer clay? Contact us today by submitting our general inquiry form. If you're ready to get started with a new crafting project or want some inspiration for a new creation, check out our tutorial page or visit our clay lines to buy your Sculpey® clay today.