Fourth of July Fireworks: What Makes Black Snakes Go, and How to Make Them Yourself

Fireworks is a Fourth of July tradition. The majesty and beauty of glistening explosions in the sky is a sight that few want to miss this time of year. But there's another kind of fireworks which has mesmerized kids (and still some adults): black snakes.

Sometimes called snakes, black snakes, the pharaoh's serpent, or their green cousin, glow worms, these are the little tablets that you set on the ground, burn, and magically they grow a long column of ash, seemingly out of nowhere. While they don't explode, fly, or burn bright, there's something amazing about watching this little black tablet burn and produce a huge snake-like pillar.

How does that happen? How to they work? Here's a little primer on the chemistry behind snakes, and how to make them yourself (Caution: this involves flammable chemicals and fire, so you should not try this unless you've got protective clothing, safety glasses, and you're a responsible adult!)

Black snakes produce the snake-like ash column through what's called an intrumescent reaction. That means that the black snakes, when exposed to heat, swell in size, increasing in volume, rather than melting, burning up, or exploding. Intrumescent substances produce char (the black column of ash) and are actually commonly used as fire protectants, as the char they produce are poor conductors of heat.

Black snakes are commonly made of mostly sodium bicarbonate, also known as baking soda and some sort of sucrose (also known as sugar), and other chemicals like ammonium nitrate or ammonium dichromate to give it certain colors or extra effects, depending on the kind of snake fireworks you buy. When heated up (and it does sometimes take a while to start a snake going), the sodium bicarbonate breaks down into sodium carbonate (the majority of the ash), water vapor, and carbon dioxide gas, while the burning sugar produces water and more carbon dioxide.

Sounds pretty simple right? Well, you can make your own snakes with materials and chemicals just lying around the house. You'll need sand, baking soda, sugar (preferably powdered sugar), sand, and a flammable liquid fuel like high-proof alcohol or lighter fluid. (You'll also need to be a responsible adult with proper protection and a safe place to set up, preferably outside away from people and flammable things).

The first step is to make a mixture of the powdered sugar and baking soda. Make sure it's four parts powdered sugar to one part baking soda (and start small, like four tablespoons to one). Make a little pile of the sand and push in a dent into the middle, like a volcano crater. Now use a little of the alcohol or lighter fluid to wet the sand, pour the sugar/baking soda mixture in the middle, and then carefully light it. The sugar and baking soda will eventually light up and produce a snake. It might not actually produce what looks like a snake - instead it might look like a huge wild plume of cloud ash or a mushroom. But it'll be a firework that you created yourself, so show it off with pride. If you're more a visual learner, check out this video from LabconoCorpoation demonstrating the above instructions. For more information on how to make black snakes with other chemicals, go here.