Underglaze can sometimes peel or flake off ceramic surfaces, which can be attributed to various factors related to application, firing, and glazing.
Improper Adhesion
Underglaze may not adhere properly if the clay surface is not adequately prepared or if the underglaze is not applied with sufficient pressure.
Firing Issues
Underglaze can peel if it has not been fired at the correct temperature or if the firing schedule was not followed precisely. Overfiring or underfiring can affect the underglaze’s bond with the clay.
Moisture and Contamination
Moisture or contaminants on the clay surface before underglaze application can hinder adhesion. Dust, oils, or residues can create a barrier between the underglaze and clay.
Glaze Interaction
If a glaze is applied over underglaze, the interaction between the two materials during firing can affect adhesion. Incompatible glazes or improper firing can lead to peeling.
Conclusion
Proper surface preparation, correct firing temperatures, and compatible glazing are essential to prevent underglaze from peeling and to achieve a durable and lasting decoration on ceramic pieces.