Road Sign Reflector


Back in the day, railroad crossing signs and road signs used clear glass marbles as reflectors. Collectors use the term “transparent” to describe these clear marbles.


Three types of base glass.

When you look at a glass marble for the first time, the Base Glass (the body of the marble) is the first feature you see, even before you see the colors and decorative lines. What is it made from? Is it clear or solid?

Base Glass is the term used to describe the main body of a glass marble. All of the decorative colors and features of a marble are built on this foundational material – the base glass.

The base glass may be clear, translucent, or opaque. Let’s examine each of these terms.

Clear based marbles are more often described as Transparent Marbles. You can see right through them. The best examples are the clear marbles used in craft projects, flower vases, or in the bottom of fish tanks. You may also hear them rattling around inside an aerosol paint can.

Transparent based marbles were called Clearies in the old days. Because light striking the clear glass marbles would easily reflect, red and amber clearies were used as reflectors (Fig. 5) in railroad signs and highway markers.

Other marbles are solid. You can’t see through them. The term collector’s use is Opaque. A good example, are the Game Marbles (Fig. 6). You have probably played with them on a Chinese Checker board. If no light can shine through the glass, it’s opaque. They are of very little value because you can’t tell an old one from a new one, and they are so plentiful.

But hold the phone! Under a light, some white opaques will glow a soft orange, yellow or green. These little surprises are called Moonies. Without a light, they appear to be opaque’s, but under a light, they actually glow.

This brings us to the third base glass category.

In between the Transparents and Opaques, are the translucent based marbles. The glass on a translucent is milky or foggy, it diffuses light. A flashlight will light it up, but you can’t see inside the marble.

The Moss Agate (Fig 7), a patch marble, with milky brown or muddy green translucent base glass, is a good example. The neat thing about Moss Agates is, they also fluoresce!

Speaking of base glass, the foundation of a marble, this may be a good place to mention Martin Christensen. In the early 1900s, Christensen, an inventor, patented a machine, which would make steal round balls. We call them “ball bearings”. Tinkering with the machinery, in the barn behind his house, he then set out to do the same with glass. In 1906, he patented the marble machine, which ignited the American Marble Revolution.

I dare say, we may not be discussing these beautiful opaque, translucent or transparent spheres of glass, if it hadn’t been for Mr. Christensen.