The Science of Fireworks

This Fourth of July, many families will be wrapping up their festivities by going to see a blazing, brilliant firework show.  No matter if it’s your local community or Navy Pier in Chicago, people of all ages marvel at the stunning displays of color and sound.  Firework displays have become very sophisticated, and every year you many notice some shapes that you have not seen the previous year.  Have you ever wondered how those shapes and colors are made?  Well, you have science to thank, particularly chemistry. 

Fireworks

To understand fireworks, you do need to understand some fundamentals of chemistry, like matter. What is matter? Matter is anything that has mass and takes up space.  For example, the smartphone, tablet, or computer that you are reading this article on is made up of matter.  Matter is made up of elements, the smallest units of matter that cannot be broken down into anything else, for instance carbon, oxygen, sodium, and chlorine.  These can be combined into mixtures as a result of chemical reactions.  For example, sodium (a metal), and chlorine (a poisonous gas) can be mixed together in the proper proportions to make sodium chloride, which is table salt.  Fireworks are made up of certain elements and each of those elements has unique properties. We can give credit for the beautiful colors that light the night sky to the different elements used. Copper gives us blue, for red we use lithium, sodium burns gold, and barium green.

The anatomy of a firework

Anatomy of a Firework (Photo Credit: Robin Moncrief)

A firework is comprised of several components, and variations of these components can produce a wide range of effects.  There are seven components to a firework:

1) Black powder – Also referred to as gunpowder, this material was discovered in China, the birthplace of fireworks, about 1,000 years ago.  It is composed of potassium nitrate, charcoal, and sulfur.

2) Stars – This is the “star” component of the aerial firework.  When assembled they look like dark round marbles, but when ignited create the brilliant colors and shapes that generate smiles on the faces of spectators.  All of the aerial shells are made by hand and workers create the shapes for each firework.

3) Break – Each break is composed of a group of stars, and for fireworks with multiple breaks, each is separated by compartments.  During fireworks displays, you may notice that some bursts are larger than others.  The tighter the breaks are wrapped, the larger the burst will be in the sky because so much force is generated, expelling the stars.  Some fireworks may contain a sound charge which creates the big boom in the sky.  To achieve this sound, an explosive called perchlorate is used.

4) Lift charge – At the bottom of the firework, there is a pouch that contains black powder.  If black powder burns in the open air, the heat and gas that are generated will dissipate quickly.  Since the powder is trapped inside a bag, the heat and gas will build pressure in the bottom of the launch tube, resulting in an explosion which frees the heat and gas.  This in turn, will propel the firework into the air, as high as 1,000 ft.

5) Launch tube – This is sometimes referred to as a “mortar” and it is usually a long cylindrical tube that has the same diameter of the firework shell.  This is important, because if the shell is too small for the tube, then the pressure from the lift charge will escape and can lead to a malfunctioning firework.

6) Main fuse – As technology evolved and fireworks became more sophisticated, fuses went from tissue paper rolled around a trail of black powder, or a sting that was embedded in the gun powder, to today where electrical wires connect the firework to a control board.  With a push of a button, an electrical current is sent from the control board to the firework fuse, igniting the lift charge.

7) Time-delay fuse – Many firework shows are timed with music and each firework is designed to explode at different altitudes.  As the firework is in the air, the time-delay fuse burns until it reaches the gunpowder in the first break.  Some fireworks can have multiple breaks, two or sometimes three.  In these instances, the time-delay fuse continues to burn after the first break and will continue to burn until it reaches the second and third breaks.

Get your friends together, and go see some fireworks this year.  Enjoy!

*** DISCLAIMER***

This article is for the entertainment and information of our readers.  DO NOT try to create fireworks on your own.  It is a violation of the law to make or use fireworks without the required permits.