There is just something magical about objects which can glow with a cold light despite having no apparent power source. This drives us to experiment, fettle, and ultimately integrate these glow technologies into everything we touch. This article is meant to shed a little light, pun intended, on the phosphorescent technologies we use for the majority of them.

The following list is roughly in order of performance:

• Green - daylight pale green - This is easily the brightest and longest lasting color. If peak brightness and glow time are your primary considerations, this is an easy choice. A good charge can still be visible after 24 hours in darkness. The glow is so bright and intense that the “actual” color is slightly off white, but upon charging it will turn pale green while still under a light source, even daylight.

• Aqua - daylight semi-translucent off-white - Somewhere between green and blue glow in terms of brightness and duration, this color is also popular for its glow performance and beauty.

• Blue - daylight semi-translucent off-white - White with maybe just a drop of gray in it under light gives way to a gentle, pure, and beautiful blue glow. A very special color for sure.

• Biohazard Green - daylight biohazard green - This has that unmistakable “radioactive waste spill” look to it, day or night. A louder more vibrant shade of green than our regular green.

• Gold - daylight neon orange - A very bold neon orange under light gives way to a bright gold in darkness. It really makes things pop under any light.

• Yellow - daylight orange-gold - Very pleasing colors all around. The bright electric yellow glow though is something to behold for sure

• White - daylight ivory - Somehow this color just sticks in your mind as special and unique. Perhaps it is because it plays a bit of a trick on the eye if moved slowly from charging to darker areas? Initially it doesn’t register as “glowing” so much as just getting purer, cleaner, and brighter white…. until eventually it becomes obvious that it is actually emitting light, not merely reflecting it.

• Ultra Purple - daylight alabaster - Photos don’t do this justice. Lightly speckled deep purple-blue, when glowing it almost looks like a blacklight, like it is right at the edge of the visible spectrum. Unique and very cool. The disadvantage of this color though is that it is the least bright of all our strontium aluminate colors and takes the most energy to charge so is best charged in direct sunlight or UV light. Very much one of the coolest colors we offer (in our opinion anyway).

• Red Calcium* - daylight coral - If ultra purple feels like it is at one limit of the visible spectrum, this feels like it is at the other. The red it produces seems impossibly deep, like blood, deeper and richer than coals in a fire. It is why, despite using calcium sulfide as its source instead of strontium aluminate and thus lacking in glow duration, we really love this color. It is worth noting that, of all our colors, this one has a noticeable advantage when charging with lower light as it can be charged by lower energy spectra.

• Red Yttrium* - daylight cream - Wanting two options for red, this is more of a red-orange-rust colored glow. Using Yttrium Oxide instead of strontium aluminate, what it lacks in glow duration it makes up for with its exotic beauty.

 A little background on glow technologies. What is phosphorescence? It is the persistent emission of light following exposure to and removal of incident radiation (ref. American Heritage Dictionary) In short, radiation excites electrons driving them up into higher energy orbitals. Over time they fall back down to their lower energy states, and when they do they release energy which is converted into photons (light)

There are a handful of different phosphorescent technologies/chemistries out there. Most people are familar, if not by name, with the results of the most common: zinc sulfide. It is the original glow-in-the-dark technology, that didn’t use radioactive isotopes anyway, and is responsible for much of the derision glow-products face. ZnS is actually as old as the mid 1800s, and we are all too familiar with that green zinc sulfide glow from things like useless watch hands which started dim and were unreadable pretty much whenever you needed them. Thankfully technology marches forward and we now have MUCH better options. Never the less, zinc sulfide is found in the majority of glow products today. Why? Well there are a handful of reasons, but it mostly boils down to being cheaper and people not knowing the difference.

We use what is commonly called strontium aluminate for all our glow colors, excluding the reds marked with an * as there are no red dopants. Although the name is “improper” because the chemistry is a bit more complex, this is what you’ll find it referred to the majority of the time. There are various dopants, grades, and added pigments all of which can affect appearance and performance. While there are a handful of glow technologies on the market, the simplified answer is that SrAl is the brightest and longest lasting phosphorescent technology. As a comparison our strontium aluminate green is about twenty times better in both peak brightness and glow duration than zinc sulfide.

Excitation (charging) is the final subject important to brush on here. Not all light sources are created equal. Again the simplified version is higher energy wavelengths, and greater intensity exposures, are better; a quick intense flash of ultraviolet light will result in brighter glows than ten hours in a dimly lit room. The excitation range for these tend to be in the blue range. Direct sunlight is great, but given that it isn’t available whenever you might want it, bright UV lights work well too. (the common inexpensive UV LED keychain lights used to check for counterfeit currency work great) Failing that, close proximity to the brightest light source you can find will suffice. Under ideal lighting conditions the pigments will be 80% charged in a couple seconds. Full charge is certainly not necessary, but takes less than 10 minutes.