... crystal powder.Average particle size range: 20~30um.Luminous color: Sky-blue.Free of dangerous, toxic, heavy metals, radiation. Friendly to human ... glow in dark is repeatable.For more information, feel free to contact us.Zhongbang Chem specializes in manufacturing and marketing ... . Glow in the dark pigments (glow in yellow-green, blue-green, sky-blue, blue-purple, red, orange, etc.)2. Glow in the dark ...