Drying is usually the stage where most of the rejects are generated, especially because of drying cracks.
The root causes are often to be found in the casting workshop, with cracks in the hollow parts of the products or coming from joint parts, not seen during the finishing step.
But also, too fast drying, uneven atmosphere (temperature or moisture), incautious storage are potential causes for the drying cracks.
From a raw materials point of view, the use of minerals allowing a good packing of particles and able to absorb or avoid crack generation lead to significant improvement of the yield.
Moreover, the numerous handling between de-molding and the kiln are stressing the pieces, and it’s sometimes needed to increase the strength of the body with higher plasticity clay