Introduction
The glazing process is a critical stage in ceramic production. The quality of the glaze layer not only affects the product's appearance, luster, and texture but also directly determines its stain resistance and wear resistance after firing. However, in actual production, various glazing defects often occur due to factors such as glaze properties, process parameters, or the condition of the body. If uncontrolled, these defects not only increase rework rates but also impact overall product yield. This paper systematically analyzes common glazing defects and their causes.
I. Glaze Pinholes
Causes: Excessively high glaze slurry viscosity, high body moisture content, or overly thick application prevent proper bubble release.
Countermeasures: Optimize glaze fluidity, reduce body moisture content, and control glaze layer thickness.
II. Glaze Layer Too Thin or Too Thick
Too Thin: Low glaze concentration leads to insufficient coverage, resulting in yellowing and lack of luster after firing.
Too Thick: High glaze concentration causes glaze buildup and cracking, especially at edges where even coverage is difficult.
Countermeasures: Adjust concentration appropriately based on glazing method (pouring, dipping, etc.).
III. Glaze Cracking or Curling
Particles too fine → High viscosity and moisture content, prone to cracking and curling;
Particles too coarse → Rapid settling, poor adhesion;
Excessive viscous materials → Excessive viscosity, also causing defects.
Countermeasures: Optimize particle size distribution, rationally add gelling agents or organic additives, and appropriately adjust raw material ratios.
IV. Glaze Peeling
Mismatched thermal expansion coefficients between glaze and body, or high-temperature reactions forming salts causing separation.
Countermeasures: Improve formulation compatibility, optimize firing processes, and avoid thermal stress and abnormal reactions.
V. Poor Glaze Luster
Excessively thin glaze layer; excessive glaze absorption by the body; volatile components or non-fusible materials in the glaze; sulfur oxides or sulfate impurities in the kiln.
Countermeasures: Ensure appropriate glaze thickness, use pure raw materials, and control the firing atmosphere.
VI. Other Process-Related Defects
Excessive water addition, over-sintered body → glaze adhesion failure; uneven glaze slurry mixing → stratification, bubbling, or cracking.
Countermeasures: Standardize glazing operations, enhance glaze slurry mixing and homogenization.
Summary
Glazing defects often stem from multiple factors including glaze slurry properties, body condition, and process control. Issues like pinholes, sagging, crazing, glaze peeling, and insufficient gloss reflect deficiencies in raw material processing and formulation matching, while also exposing deviations in glazing operations and firing processes. By stabilizing glaze slurry properties, optimizing process parameters, maintaining body-glaze compatibility, and ensuring stable equipment operation, manufacturers can not only reduce defect rates but also significantly enhance product surface quality and production consistency, thereby strengthening market competitiveness.