Heavy Glaze Defect in Ceramics: Causes & Analysis

Heavy Glaze Defect in Ceramics: Causes & Analysis

Overview

Heavy glaze defect occurs when an excessive amount of glaze is applied to ceramics, causing it to run off to the bottom or corners during firing. This defect is also referred to as glaze drop.

Primary Causes

• Over-application during spraying: When glaze is applied too thickly, it accumulates in certain areas and flows down during firing.

• Over-firing: Excessive kiln temperatures cause the glaze to melt more than intended, leading to increased flow and pooling.

• Over-grinding of glaze raw materials: This reduces viscosity, making glaze more prone to running during firing.

Prevention Measures

The following steps can help control and prevent heavy glaze defects:

• Closely monitor and maintain proper glaze thickness during application

• Ensure even and consistent glazing to prevent excess accumulation

• Implement proper control of glaze preparation and firing parameters

Corrective Actions

Several corrective measures can be implemented to address heavy glaze defects:

• Sponging: Remove excess glaze from the bottom and corners of wares before firing to significantly reduce glaze runoff.

• Design modifications: Round the edges and bottoms of wares during design and production, as sharp corners tend to trap more glaze and cause pooling.