How is Reflective Paint Made? (click to shop)
Retro reflective paint is made by intermixing clear polyurethane paint with either white standard glass spheres (beads) or silver metalized glass spheres (beads). To help keep the beads in solution, an anti settling agent can be also be used. The purpose of the clear polyurethane is to bond the beads to the surface of the object being coated. Exposed beads that sit higher than the paint surface are what provide reflectivity. To enhance this effect, we use plenty of reflective powder in our paints.
Because glass beads are heavier than liquid polyurethane, the beads tend to sink to the bottom of the container over time, so when you are ready to paint, the container should be shaken, and then stirred. I normally stir, then immediately dip my brush in and paint. This assures a plentiful supply of beads in the coat and an even distribution over the surface.
It would seem that the thicker the coat, the better, however, the coat actually needs to be thin so that beads are exposed through the top of the layer of clear. This allows light to enter the microscopic beads, bounce off the back, and exit the way it came.
Silver Metalized Beads versus Standard White (clear) Beads
Silver beads, which are dark in color, actually reflect at twice the intensity that white (clear) beads do. This is because the metalized finish of the silver beads gives them a mirror backing which reflects light much more efficiently. Reflective Paint made with metalized silver beads in preferred for applications where a bright return of light is required.
White beads do not have a metalized coating, so they appear to be white in color, although they are actually clear. Light enters these clear beads and reflects, but just not as intensely. Reflective Paint made with clear (white) glass spheres is preferred when a more clear or white coating is desired and reflectivity does not need to be as intense.
In summary, retro reflective paint is made by mixing a clear medium like polyurethane with microscopic glass beads, either silver metalized, or white standard. The beads that are exposed take in and return light back to the source, hence making the paint reflective.