Stains used for ceramic glazes
Stains used for ceramic glazesmust be fired at temperatures above the firing temperature of glazes so that the color does not disappear after firing. In addition, the colors must match well with the chosen glazes. The colors will appear as intended because some colors are not suitable for glazing with zinc, some colors are not suitable for glazing with lead, some colors are incompatible with magnesium glaze, etc.
When grinding the color in the glaze, the glaze should thoroughly be ground before adding the color near the end of grinding and continue grinding for a while. Or, if it's a fine finished color, grind the clear glaze separately and add the pigment to the glaze then stir the ingredients together.
Color powder used to prepare various glazes must be suitable for the production of coatings which is different from the mixed color in the clay both the raw materials used in production and the reactions that occur during the firing. The structure of the color mixture in the glaze is not as strong as the color mixed in the clay. Therefore, it will react to melt with the glaze while melting. After firing, the fine grains are stable and will be melted into the glazes
When the factory produces the color used in the glazes and then the test is carried out with a metal-coated drag method, which is a paint splatter. By taking the old standard color to compare with the new color and fire it. After firing, the test color will be clearly visible in the same test base before being measured with a colorimeter.