Why is my polymer clay cracking?

Working with polymer clay can be a delightful and creative experience, but encountering the frustration of cracked clay can be disheartening. Cracking is a common issue that polymer clay artists may face, and understanding the potential causes can help you prevent and address this problem. In this article, we will explore why polymer clay may crack during and after baking, and provide insights into how to troubleshoot and avoid cracking.

1. Insufficient Conditioning

One of the primary reasons for cracking in polymer clay is insufficient conditioning:

Polymer clay needs to be conditioned thoroughly before use to ensure that it is soft, pliable, and free of air bubbles. Inadequate conditioning can result in uneven distribution of particles and air pockets within the clay. As the clay is baked and hardens, these inconsistencies can lead to cracks forming along weak points.

2. Improper Baking Techniques

Incorrect baking techniques can also contribute to cracking:

If polymer clay is not baked at the correct temperature or for the recommended duration, it may not cure properly. Incomplete curing can result in weakened clay that is more prone to cracking. Additionally, sudden temperature changes during or after baking can cause thermal shock, leading to cracks.

3. Overworking the Clay

Overworking the clay can lead to cracking:

Excessive rolling, folding, or manipulating the clay can cause stress and strain on its structure. This stress can weaken the clay and create microscopic fractures that develop into visible cracks during or after baking.

Addressing and Preventing Cracking

If you encounter cracking in your polymer clay projects, here’s what you can do:

  • Thorough Conditioning: Ensure that you thoroughly condition your polymer clay until it is soft, smooth, and free of air bubbles before starting your project.
  • Follow Baking Instructions: Always follow the manufacturer’s recommendations for baking temperature and duration. Use an oven thermometer to ensure accuracy.
  • Avoid Sudden Temperature Changes: Allow your baked clay to cool gradually in the oven or on a heat-resistant surface. Avoid exposing it to drastic temperature changes, which can cause cracks.
  • Handle with Care: While working with clay, handle it gently to avoid overworking and stressing the material.
  • Test and Experiment: If you’re using a new brand or type of polymer clay, conduct test bakes to determine the optimal baking conditions and techniques.


Cracking in polymer clay can be attributed to factors such as insufficient conditioning, improper baking techniques, and overworking the clay. By understanding these causes and implementing proper techniques, you can reduce the risk of cracking and create polymer clay projects that are smooth, durable, and visually appealing. With care and attention to detail, you can enjoy the creative process and achieve successful results with your polymer clay endeavors.

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