Colour Test for Ceramic Glaze: Methods & Analysis

Colour Test for Ceramic Glaze: Methods & Analysis

Colour testing is performed on all raw materials to ensure consistency in supply and also for the production glaze. Colour test helps to compare the raw materials supply consistency.

Sample Preparation and Testing Method

A sample is evaluated using a spectrophotometer. For this test, a flat sample is prepared using the pressing method. Raw materials with added moisture content are pressed at 200 kg/cm² to form a sample button.

For production glaze colour testing, the glaze is sprayed or poured onto a cast slip body, and the sample is then fired.

Spectrophotometer Analysis

The fired sample is analyzed using a spectrophotometer, which measures the following parameters:

• L: Represents lightness, ranging from 0 (black) to 100 (white)

• a: Indicates the position between green and red

• b: Represents the position between blue and yellow

Colour Difference Calculation

Using L*, a*, and b* values, the ΔE value is calculated by comparing the colour of the standard sample with the colour of the supplied result. This ΔE value helps the lab determine the magnitude of the colour difference between the two samples.