Clay Bits Defect in Ceramics: Causes & Analysis

Clay Bits Defect in Ceramics: Causes & Analysis

Clay bits are small fragments of clay that appear on the surface of a glazed ceramic product. They can sit on top of the glaze or get trapped just beneath it. This defect affects the surface finish and appearance of the final ceramic product.

What Causes Clay Bits?

1. Clay Bits Left on Body Before Glazing

Sometimes small pieces of dried clay or body material remain on the surface of the ceramic product before the glazing process. When the glaze is applied, these small pieces get covered by the glaze. During firing, these clay bits heat up differently from the surrounding glaze and body, creating raised spots or rough patches on the surface.

2. Clay Bits Falling During Kiln Firing

Another cause is clay particles falling from the kiln furniture, kiln walls, or the roof of the kiln during firing. These particles can land on the glaze surface while it is still soft and melted during high-temperature firing. When the kiln cools, these particles remain stuck to the glaze surface, creating the clay bits defect.

How to Prevent Clay Bits Defect

• Clean the ceramic product body thoroughly before applying glaze to remove all loose clay particles
• Maintain cleanliness in the glazing area to prevent contamination
• Inspect and clean kiln furniture, shelves, and walls regularly to prevent loose particles from falling on products during firing
• Use good quality kiln furniture that does not shed particles at high temperatures

Impact on Product Quality

Clay bits defect creates a rough and uneven surface on the ceramic product. Depending on the size and location of the clay bits, the product may be downgraded or rejected in quality inspection. Minor clay bits may be removed by grinding, but this can affect the glaze finish.