Applying underglaze too thickly can result in issues such as cracking, chipping, or uneven color during the firing process.
Drying and Shrinking
Thick underglaze takes longer to dry and can shrink significantly during the drying process, which may lead to cracking or flaking.
Surface Tension
Excessively thick underglaze can create uneven surface tension during firing, causing the underglaze to pull away from the clay body and potentially chip off.
Firing Considerations
Firing thick underglaze too rapidly or at too high a temperature can contribute to chipping or other defects. Follow recommended firing schedules for underglaze application.
Application Techniques
Using multiple thin layers of underglaze is generally more effective than applying a single thick layer. Experiment with application techniques to achieve your desired results.
Conclusion
To avoid chipping and other issues, it’s important to apply underglaze in thin, even layers and follow proper drying and firing procedures.