Is Glow in the Dark Really a New Concept?
Everyone loves glow in the dark, who wouldn’t? But did you ever wonder how glow in the dark came to be? You may be thinking that a sorcerer or alchemist created magic glow crystals to ward off the darkness. Well, you are partially right! From the beginnings of its early discovery to the multitude of uses available today, there is much to learn about this fascinating subject.
What is Photoluminescence?
Let’s start with an understanding what photoluminescence really is. Photoluminescence by definition is the emission of light from a molecule or atom that has absorbed electromagnetic energy. The ingredient that causes the glow is phosphor, and its various compounds are called phosphorescents, or materials that glow in the dark. The glow material exhibits luminescence when charged by certain wavelengths of light. Light sources ideal for activating phosphor include sunlight, ultraviolet or black lights, and room lighting such as fluorescent, halogen and incandescent bulbs. That is why when you charge glow in the dark material under a light and view it in a dark room, it glows.
There are early reports dating back to ancient China about the amazing glow in the dark phenomenon of fireflies and glowworms. Remember that song you sang as a child: “Glow little glow worm, fly of fire. Glow like an incandescent wire”? Glow worms are bioluminescent glow creatures and have long interested scientists and children alike.
Among the earliest records of objects that glow in the dark was back in 1602 when Vincenzo Casiarolo discovered a phosphorus glowing stone just outside of Bologna, Italy. Casiarolo began the first true scientific study of luminescence. However, it was German alchemist Hennig Brand who truly claimed the discovery of a commonly used material still recognized today. Brand is sometimes called “the last of the alchemists”, a group who were searching for materials to gain eternal life.
As alchemy contained more magic than science, it was not considered a truly scientific discipline. However, many important discoveries were made, including that of phosphorus glow. In 1669, Brand found a way to isolate the element phosphorus by creating a chemical reaction from mixing urine, which contains phosphates, and other carbon based organic materials to the phosphorus rock by applying high temperatures. Using urine for experiments may seem a bit gross but his results were successful!
How is glow created?
Not all glow is produced the same way. There are chemically induced glow materials (chemiluminescence), photon light activated glow materials (photoluminescence), elements that when violently crushed cause fracture stresses that emit tiny bursts of light (mechanoluminescence), and electrical current induced glow (electroluminescence).
Hundreds of years before the modern world recognized mechanoluminescence, the Uncompahgre Ute Indians from the central Colorado area filled rawhide rattles with special Quartz crystals. Used at important ceremonies, when shaken in complete darkness it produces flashes of light, thought to be quite magical at the time.
One interesting home experiment involves crushing sugar cubes. Sit in a dark room with your eyes adjusted to the darkness. Place the sugar cubes on a white plate and sprinkle some loose sugar onto the same plate. With the flat bottom of a clear glass, quickly crunch the cubes and loose sugar to break down the cubes. The result will be tiny quick flashes of luminous blue glow light.
So now that you know some of the historic beginnings of glow in the dark, let’s see how we apply glow in the dark today. In 1977, Richard Taylor Van Zandt invented and patented a Chemical Light Device, more commonly known as liquid glow sticks that are intended for a single use (chemiluminescent). Also developed in the 70’s to the delight of children everywhere, were cool new glow in the dark (photoluminescent) toy monsters, pirates and aliens that inspired playtime imagination and could provide fun even after parents put kids to bed. Remember the Star Wars movies? Where would Luke Skywalker be without his glowing light saber (electroluminescent)?
In the 1980’s, more serious uses for photoluminescence were developed particularly for safety signage and applications. Just think of the many glow in the dark products that we might encounter. Glowing cautionary and road condition signage is becoming more common. As higher quality glow materials now offer brighter and longer lasting glow properties, more consumer applications can be designed with enhanced safety benefits.
Fast forward to today, here at Lunabrite, we continue to work on cutting edge photoluminescent technology. Although humans have known about glow in the dark technology for centuries, high performance glow materials are becoming ever more popular as the demand for nighttime visibility grows. Just think of the glow in the dark possibilities for the future!