色・発色
reaction line
Japanese: 反応境界線
A colored line that appears at the boundary between reacting pieces of glass. The core of reactive expression.
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A reaction line is a banded color pattern that forms at the interface where two glass pieces containing different metal oxides come into contact and melt during firing. Metal ions dissolved in the glass undergo a chemical reaction at the interface, producing a unique color distinct from that of the glass on either side. This phenomenon produces a variety of patterns depending on the composition of the glass and the firing conditions.
While reaction lines may appear to be defects when they occur unintentionally, they can become a distinctive expressive element of a piece when intentionally incorporated into the design. In particular, when combined with a silver reaction, they produce complex and beautiful linear patterns. To control reaction lines with consistent results, it is necessary to understand the glass composition and conduct repeated test firings.
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.