Reflective paint is mixed with glass beads in the paint, and the total reflection occurs in the glass beads after the light irradiation, which can basically return the direct light from afar to achieve the effect of luminescence. But if there is no source of light, then the reflective paint has no luminous effect, because it does not emit light itself.
In fact, there are many such examples around us: not only street signs on the side of the road, but also car license plates. If you look closely, you will find that the reflective paint can be seen with the naked eye: it seems that the paint surface has depth, and it seems that there are many small bead-like structures closely connected. You can have a magnifying glass to see for yourself.
