Well Glow in the Dark is a very cool and interesting phenomenon that when harnessed, has almost unlimited applications! From Glow in the Dark Paints to Toys, to entire glowing cars to even the sticky stars you put on your ceiling at night, you start to see the picture. Read further to understand what makes Glow in the Dark Stuff Glow and then get some ideas on how to incorporate Glow In the Dark into the stuff around you every day!
The Glow in the dark property is also know as Luminescence – which in turn simply means an object that has chemical properties that store energy when exposed to light. These special energy storing chemicals are called Phosphors which give way to a second term for glowing: “Phosphorescence”. To put it simpler:
Glow In the Dark Objects contain Chemicals which have the property/ability of Luminescence.
“Phosphorescence” (derived from the word Phosphors) means the same as “Glowing”.
How Do Phosphors Glow?
Now that we have the basics, we now need to explore how Phosphors Glow! This is actually quite simple. As we know all atoms in matter radiate – Phosphors, being matter… radiate. The difference is that over time as Phosphors charge in the light they continue to build up energy. Once they are fully charged they begin to radiate and in turn that radiating frequency creates the glowing effect perceivable to the human eye! Pretty cool huh?
Even cooler than that – the rate that Phosphors release this stored energy is slowly – so its not all at once. This is why when you have an object that glows in the dark – and you leave it in the sun all day to charge – it will glow for hours through the night… if not ALL Night!
How Long Does My Stuff Glow For?
Depending on the type of chemical in the product determines the length of time that the product will glow. Over the years chemists have created a multitude of substances that behave like phosphors – charging in light and glowing in the dark. All of the products using phosphor substances have three main characteristics:
- Energy Needed to Energize the Element
- The Visible Light Color they Emit
- The Glowing Length of Time (this is called the Persistence of the Phosphor)
To make a product, toy or anything glow longer the chemist needs to add a phosphor that is energized by every day lighting sources (the sun, interior lighting, etc.) and in turn has a very long persistence. The top phosphors with these properties are: Zinc Sulfide and more recently discovered Strontium Aluminate. By far Strontium Aluminate has the longest persistence and is fast becoming the more popular of the chemicals.
On a side note – on occasion you might see an object (typically in high end watches) that does not need light to charge – it is naturally always glowing! How does this happen?! Well in this special case the phosphor is mixed with a radioactive element. What… Radioactive? Yes! But don’t be alarmed these days the radioactive element is an isotope of Hydrogen called Tritium (Tritium has a half life of 12 years) or Prometheum (half life of three years), a man made radioactive element.