色・発色
coloring vs discoloration
Japanese: 着色と変色
Coloration = the process by which a metal is oxidized; discoloration = the process by which metal ions are sulfidized. It’s a fine line between what’s intended and what goes wrong.
Learn More
"Coloring vs. Discoloration" is a concept that distinguishes between "coloring," the intentional addition of color to glass, and "discoloration," the unexpected change in color that occurs during firing. Coloring is a phenomenon in which a stable color is achieved using colorants such as metal oxides. Discoloration is a phenomenon in which the original color changes due to color burnout, reduction blackening, silver reaction, devitrification, and other factors.
By being mindful of the distinction between the two, you can establish a thought process for identifying post-firing color abnormalities (discoloration) as a problem and investigating their causes. For example, if “red turns orange,” you can infer that the cause is “color burnout” resulting from high-temperature firing in cadmium-selenium-based glass. By combining knowledge of coloring and discoloration, you can prevent color-related issues and analyze their causes.
Related Concepts
See “Metal Oxide,” “Cadmium Selenide,” “Silver Reaction,” “Color Burnout,” and “Color Sample Tile.”
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.