Zoltán Ficsor (asker) Jan 25, 2022:

Most találtam. Ezek szerint valamilyen öregítési folyamatról van szó: Some Bullseye glasses appear pale or colorless in the cold sheet form, but “strike” or mature to a much different color when fired. Striking colors can vary, depending on temperature, atmosphere, and heat history.

Producing strikers allows for a greater palette of colors for kilnworkers. And because heat work is cumulative, we use the minimum amount so that kilnworkers can use more of it in their studios.

For projects that are especially color-sensitive, we recommend testing your striking glasses prior to use either by fusing or torch working small samples. This will help you predict final color results.