What is the “Lumi Brite” used in Seiko watches?

LumiBrite is the latest development in Seiko luminous paints. Conventional luminous paints all used to rely on radioactive substances to generate their afterglow. Then came fluorescent paints that glowed in the dark by releasing light energy stored while the surrounding light was bright. Their freedom from radioactivity and its potential hazards was a great advantage, but their glow tended to be short-lived, fading rapidly as the stored light-energy was discharged. LumiBrite is a dramatically improved fluorescent luminous paint that quickly absorbs more of the light-energy falling on it and glows brighter, for much longer, in the dark. Safe and harmless to human beings and the environment, it is completely free of radioactivity and can be used without restriction--covering the entire dial, for instance.

A LumiBrite dial will glow at its full brightness after only brief exposure to bright light. For instance, just ten minutes under normal room lighting will often be enough--much less under sunlight. LumiBrite, as its name suggests, starts glowing brightly in the dark, and fades slowly. It is the ideal successor to both radioactive luminous paint and conventional fluorescent paints.