A party and event favourite, glow sticks have been around for some years but continue to grow in popularity.
Glowsticks contain two chemicals, separated in some way. When the two chemicals mix, they produce light for a limited amount of time. Common glow sticks consist of a plastic tube containing one of the two chemical components, inside which is a thin glass vial containing the other chemical component and - usually - a fluorescent dye to colour the glow. When the outer plastic container is bent, the inner glass vial breaks and allows the two chemicals to mix beginning the chemical reaction that causes the glow. The duration and intensity of the glow is dictated by the amounts of each chemical present and the current temperature.
What’s inside my glowstick?
There are many chemical combinations that will produce this glowing effect including some rather nasty chemicals including one called called DBP or Di-Butyl Phthalate which has been banned in the European Union because it is harmful to your health. The most common and probably the safest chemical components for glowsticks is Hydrogen peroxide and tert-butyl alcohol. Of course, not all glowsticks are created equal, the quality and purity of the chemicals used in the manufacture of the glow sticks can greatly affect the brightness and duration of the glow.
Temperature also affects the duration and intensity of a glow-stick’s glow, the warmer it is, the brighter the glow stick will illuminate, but for a shorter time. Conversely the colder it is the longer - and dimmer the glow. This gave rise to the myth that freezing a glowstick, after it had been activated, would ‘re-charge’ it and allow you to use it again. Sadly this isn’t true, freezing an activated glowstick will slow or even stop the chemical reaction causing the glow to stop or become very dim, defrosting the glowstick will only allow the reaction to carry on. At the best, you could possibly use this method to make one glowstick last for a couple of nights, but once the glowstick has finished glowing, the chemical reaction cannot be reversed.
How long do glowsticks last?
On average, a good glow stick should glow for around 8-12 hours after activation - temperature permitting - normally a faint glow can be seen for up to 24 hours later, but the glow will be brightest and most visible within the first 8-12 hours. A glow stick that has not been activated should normally ‘keep’ for around 2-3 years from the date of manufacture. To get the best ’shelf-life’ from glowstick products, they should be wrapped up away from bright light sources - especially direct sunlight - and protected from extreme temperatures and bumps and knocks that could accidentally activate them.
Some glowstick products, such as glowstick necklaces, are particularly fragile and can be accidentally activated very easily with only a sleight bend in the stick - even removing them from their packaging can cause them to activate and it is a good idea to leave them in their packaging tube or carton until you’re ready to use them and only remove the quantities you wish to activate immediately. To store necklaces once the tube has been opened, it is advisable to pad the tube with tissue or tissue-paper to prevent the remaining necklaces from rattling around, bending and activating in the tube.
What’s the brightest colour glowstick?
The brightest colours in the glowstick spectrum are Green, Yellow and Orange. Although it is possible to mix a white light stick, the colour is not as bright as any of the top three. This is because the white colour is formulated using a few other colours which makes the white glow slightly dimmer and, after a while, a white glowstick begin to hint with other colours such as pink or pale blue - sometimes both. For safety applications, green, yellow and orange glowsticks are the most commonly used colours. Green is especially useful in emergency situations, since the green coloured light is the most visible.
It is also possible to formulate high-intensity glowstick - glowsticks that illuminate much brighter but last for shorter amounts of time. These glowstick ‘Flares’ are commonly made to last between 5 and 30 minutes and glow very brightly. They have been used both for safety and hazard markings at night and for performing arts like juggling and poi spinning.