This page discusses and illustrates now-antique but still-extant reflector technologies and shows admittedly unfair comparisons of two of such examples and the Tri-Color Triangle ™
Growing up in Northern Indiana in the 1960s and 70s, our town still had some of the old Chicago Motor Club road signs on the streets. Recently I ran across an example still up in a private subdivision on the shores of Lake Michigan in Harbor Country. Being on my bike at night, I couldn’t resist using my flashlight and the camera’s flash to document the retro-reflective qualities of the baked-on glass beads on part of this old sign to see how it still performed by itself, compared with my bike’s “reflectors”, and with the Tri-Color Triangle ™ with modern cube-corner reflective sheeting. Well, that last comparison was like taking a gun to a knife fight. Here’s the shots, including ones taken in daylight — regular distance and close-up of the transition from plain paint to beaded sections. Following the pictures are some documents referencing glass-beaded license plates and their comparisons to “reflective” sheeting (old engineering grade). A telling finding was how much better even old sheeting was at being effective at an angle than standard cars’ “reflectors.” The same can be said for SMV emblems that still use molded reflex red strips. (see orange text further down)
The finest 1950s-60s safety technology… an improvement over separate individual glass “Cats Eyes” (stop sign following)
Close-up of the glass beads coating to make the center of the sign reflective (bottom section, vs. plain paint on top).
‘Reflectorized’ license plates (ca. 1974, using engineering grade sheeting) retain much of their ‘reflectivity’ at light entrance angles of up to 50 degrees. On the other hand, automotive vehicle reflex ‘reflectors’ retain much of their reflectivity at light entrance angles of only up to 20 degrees. A license plate of ‘reflectorized’ sheeting is of about the same reflectivity as an automobile reflex ‘reflector’ at entrance angles up 10-15 degrees. Thus, all things being equal, a ‘reflectorized’ license plate would return the same amount of light as a vehicle reflex ‘reflector,’ if the incident light was within 10-15 degrees from their axes. Beyond entrance angles of 20 degrees license plates of ‘reflectorized’ sheeting will generally return more light than a vehicle reflex ‘reflector’*. Among the license plates tested, only the license plates with ‘reflective’ sheeting backgrounds conformed to the SAE standard for vehicle reflex reflectors.”
*this is a good reason for eliminating the provision that allows SMV emblems to continue to incorporate molded reflex ‘reflectors’ for the red strips around the orange triangle… they do not ‘reflect’ as well from angles as either the old engineering grade or the new cube-corner sheeting does.
In the 1930s “Catseye” ‘reflectors’ were invented. This technology utilized marble-sized glass ‘reflectors’ and possibly even marbles themselves in some applications; this being a super-sized version of the previous glass microspheres shown on the Chicago Motor Club sign. The old stop sign shown here is in my collection and had been given a sloppy fluorescent upgrade by a previous owner.
The pictures here show the sign illuminated by both the setting sun and the rising sun, and then side-by-side with the T-C T for yet another totally unfair comparison. The cat’s eyes in this sign could possibly be red marbles instead of actual patented Catseyes, something that would have saved the manufacturer some money, though at the tradeoff of effectiveness… something that has at times crept into the manufacture of SMV emblems.
The stop sign illuminated by the setting sun.
One thing that makes the comparison with a cat’s eye sign unfair is that by nature this very old sign cannot look the same by night as it does by day. Cat’s eyes and their backing method for mounting were expensive and heavy. A string of separate dots within the letters was about all that could be come up with in making such signs. Too many cat’s eyes and the effectiveness of the black letters against yellow background in the day would have been diminished.
That problem of dissimilar appearance was similar to how conventional SMV emblems through version 276.7 have failed to appear similar enough by day and night… no longer a factor with the all-retro-reflective Tri-Color Triangle ™.
Below are pictures of and links to articles on the Cat’s Eye reflectors — still in use in Europe and elsewhere as pavement markers.
Above diagaram from Wikipedia: https://en.wikipedia.org/wiki/Cat’s_eye_%28road%29
Other interesting links on this invention and its creators are
Michiganians can say goodbye to their “Old Blue” license plates since the Secretary of State announced earlier this month that it will stop issuing it at the end of the year. About 5.6 million motorists use the “Old Blue” license plate design, which was introduced in July 1982, according to the Secretary of State. “The license plate has been around for roughly 24 years, and most states replace their plates within five to 10 years,” said Kelly Chesney, spokesperson for the Secretary of State. Having a reflective background on license plates will improve visibility on roadways and allow law enforcement officers to perform their public safety duties better. Secretary of State Terri Lynn Land said in a written statement that she feels it’s time to use newer technology to create the license plates. “This change will also allow the state to use the same type of material for all of its license plates, which makes production more efficient,” Land said in the statement. Michigan is the only state in the nation that uses the costly and outdated process of applying finely ground glass beads to the characters on the license plate during production, Chesney said. Small, glass beads that have the consistency of sand are sprinkled on the wet white paint on license plates to give them limited reflectivity. As registrations expire, Michigan residents will be issued the new plates. “From a public safety perspective, having license plates that are easier to read at night will assist law enforcement in keeping our streets safe,” said state Rep.