Cracks in ceramics — the ultimate heartbreak for any potter! You’ve spent hours molding, shaping, and perfecting your piece, only to find it cracked during drying or firing. But fear not! In this blog, we’ll guide you through the common reasons why cracks happen and, more importantly, how to avoid them. Let’s make sure your next piece comes out as smooth and flawless as you imagined!
Ceramics typically crack due to uneven drying, rapid temperature changes, or structural weaknesses in the clay itself. These sneaky cracks can happen at any stage of the process—while you’re working, during drying, or even after firing.
Here’s how to avoid them:
Inconsistent thickness across your piece is a common reason for cracking. Thin areas dry faster than thicker areas, leading to tension in the clay. Try to keep the thickness of your walls as even as possible. Whether you’re handbuilding or using the pottery wheel, this will help the piece dry evenly and minimize the chance of cracking.
When attaching two pieces of clay, it’s essential to properly score and slip. This creates a stronger bond between the pieces. If you don’t score deeply enough or forget the slip, the pieces may separate as they dry or fire, leading to cracks at the seams.
Pro tip: Always score both sides, use plenty of slip, and press firmly but gently to make sure your pieces are fully attached!
The more you handle the clay, the more it can lose its elasticity and moisture balance. Overworking your piece can make the clay dry out too much in certain areas, leading to cracking. Be mindful of how much you’re handling the piece, and try to keep it as moist as possible during the construction stage.
Trapped air bubbles in your clay can expand during firing and cause cracks or even explosions in the kiln. To avoid this, make sure to wedge your clay properly before starting your project. Proper wedging removes air pockets and creates a more consistent clay body.
In our studio we prepare clay for our students. But still, some bubbles might sneak through. In this case - just pop them with a needle tool and smooth the surface.
One of the main culprits behind cracking is uneven drying. Clay shrinks as it dries, and if one part dries faster than the other, cracks can appear. In our studio we take well care of the drying process: we don't place your pieces in direct sunlight or under a fan. Instead, we let it dry slowly and evenly in a cool, shaded spot. For larger or thicker pieces, we cover them loosely with plastic to slow down drying even more. Patience is key!
Cracks often happen during firing, especially during the first (bisque) firing. If your clay is still damp inside, the water will turn to steam and expand rapidly in the kiln—resulting in cracks or even explosions!
That's why in our studio we make sure your piece is completely dry before placing it in the kiln. But this takes time! Depending on the size and thickness, this can take anywhere from a few days to a week. Don’t rush it — patience always pays off!
Cracking might feel inevitable at first, but with the right techniques and a little patience, you can significantly reduce the risk. Slow down, take care during making and drying, and don’t forget to score and slip those seams!
In our long-term courses we discuss each step of ceramic production and look into most common mistakes. We offer both 1-month and 3-month programs designed to help you master the craft. Check out the schedule for the next course!
