Retroflective device and method of manufacture thereof

A retroreflective device 1, for use in creating a retroreflective surface, comprises an agglomeration of glass beads 2, formed by binding together glass beads 2 of a specific size with an adhesive material 3. Selected properties, for example refractive index, of each glass bead 2 are chosen in accordance with the desired retroreflectivity of the device 1. The adhesive material 3 may be pigmented, thereby to colour light retroreflected from the device 1. Preferably, the agglomeration of glass beads 2 is approximately spherical or ovoid and the glass beads 2 are approximately spherical. A retroreflective road marking coating may comprise a road marking material applied to the surface of a road and a plurality of the retroreflective devices 1 embedded in the road marking material so as to protrude partially therefrom. The retroreflective devices 1 may also be used with a coating from which they protrude so as to provide a road surfacing material.