Why does the underglaze red of raw ore glow in the sun?

The content of copper ion in raw ore glaze is high.

The raw ore glaze red glows in the sun because the content of copper ions in the round frame glaze red is very high, and copper ions are extremely sensitive to temperature. At high temperature, copper ions will volatilize and escape from the glaze layer, showing a unique flashing red phenomenon.

The biggest feature of underglaze red is that it is difficult to fire and the yield is extremely low. It is called "underglaze red" because it uses copper as colorant, directly draws various patterns and patterns on the white tire, and applies a layer of glaze on it.