How Do Fireworks Actually Work?

iStock
iStock

by Sarah Dobbs

Each year, as the Fourth of July approaches, the sound of explosions starts to become a normal part of the evening. Fireworks have existed in one form or another for around 1000 years, and they show no signs of going away anytime soon. But how do they work? Most of us just know to light the fuse and stand back. Let’s take a closer look …

ROCKETS

fireworks over new york city
iStock

Rocket-type fireworks can produce all kinds of different effects when they go off, but the basic structure of an aerial firework stays more or less the same. Each rocket is made up of the following parts: a mortar, fuses, propellant powder, a shell, a bursting charge, and a collection of "stars." The mortar is the outer container, and the fuse is, of course, the piece that you light. When the fuse burns down, the propellant ignites and shoots the firework into the air.

When it’s airborne, a second explosion is triggered inside the shell by a time delay fuse. The bursting charges set off the stars—small, explosive pellets made of fuel and metallic compounds that create the lights in the fireworks display. Different metals create different colors when they ignite: barium goes green, calcium salts go orange, magnesium goes white, copper is blue, lithium turns red, and sodium becomes gold. And the arrangement of the stars will determine the shape of the explosion—so if they’re packed in a heart shape, they should reproduce that heart shape in the sky.

Other effects can also be built in by adding various ingredients; different kinds of fuel can create sound effects, for example, like the whistling or screaming noises some rockets make as they shoot into the sky. Stars can be made up of layers of different metallic compounds, to create multicolored explosions. And in some more complex fireworks, there may be several stages of explosions; in that case, there are generally multiple fuses inside the shell, and as each burns down, a different explosive goes off.

FOUNTAINS

fountain type fireworks
iStock

Of course, not all fireworks are of the shoot-into-the-air-and-go-bang variety. Fountains don’t take off, and generally don’t go bang, either; instead, they stay where they’re placed and give off a cascade of sparks—like a fountain, but with pyrotechnics instead of water.

Usually conical in shape, fountains consist of a paper or plastic tube, with clay plugs at either end. Inside the tube are a couple of different kinds of fuel, plus the metal compounds that create the sparks. When the fuse is lit, the fuel ignites, and sparks are forced out of an aperture in the top of the fountain.

Again, different metals create different colors and effects. Multi-stage effects can be created by bundling multiple tubes together, so that as one finishes another starts, adding different colors or sound effects to the display.

CATHERINE WHEELS

wheel firework
iStock

Catherine wheels are another common type of firework, and again the same kinds of ingredients are used to create a slightly different effect. Named for the unfortunate Saint Catherine, these fireworks are generally fixed to a pole or a mount, so that they can spin as they burn, creating a spiral of sparks.

Bigger Catherine wheels tend to have a plastic disk at their center, with “gerbs” attached around the edge. The gerbs are similar to fountains, in that they’re tubes filled with the mixture of ingredients that create the effects; when lit, the thrust from the explosives makes the wheel turn as they burn. And again, the effect can be made more elaborate with multi-stage effects and different colors; each gerb might be different, so that the wheel changes as each one ignites in turn.

Smaller Catherine wheels might, instead, be made up of a single long, thin tube coiled into shape around a smaller central disk. Again, the thrust of ignition makes the wheel spin.

SPARKLERS

person holding sparkler
iStock

The only firework you should ever hold in your hand once it’s lit is a sparkler—a Fourth of July staple. Unlike most other fireworks, they don’t explode with a bang, but gently fizzle for around a minute, as a ball of sparks makes its way down a metal wire. And they’re pretty simple: basically, the metal wire is dipped into a pyrotechnic compound that’s made up of a metallic fuel, an oxidizer, and a binding material.

The metallic fuel is what creates the sparks; it’s usually aluminum or magnesium, which creates white sparks, but some sparklers may use iron or ferrotitanium for gold sparks instead. The oxidizer, which provides the oxygen to keep the spark going, is generally potassium nitrate. And then a binding material, a kind of flammable starch, keeps the mixture together, and burns away once the sparkler is lit.

Hopefully, none of that has taken away any of the magic of a good fireworks display. If nothing else, you’ll be able to impress your friends by quietly musing “oooh, barium” next time you see a green firework.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Why Does Santa Claus Give Coal to Bad Kids?

iStock/bonchan
iStock/bonchan

The tradition of giving misbehaving children lumps of fossil fuel predates the Santa we know, and is also associated with St. Nicholas, Sinterklaas, and Italy’s La Befana. Though there doesn't seem to be one specific legend or history about any of these figures that gives a concrete reason for doling out coal specifically, the common thread between all of them seems to be convenience.

Santa and La Befana both get into people’s homes via the fireplace chimney and leave gifts in stockings hung from the mantel. Sinterklaas’s controversial assistant, Black Pete, also comes down the chimney and places gifts in shoes left out near the fireplace. St. Nick used to come in the window, and then switched to the chimney when they became common in Europe. Like Sinterklaas, his presents are traditionally slipped into shoes sitting by the fire.

So, let’s step into the speculation zone: All of these characters are tied to the fireplace. When filling the stockings or the shoes, the holiday gift givers sometimes run into a kid who doesn’t deserve a present. So to send a message and encourage better behavior next year, they leave something less desirable than the usual toys, money, or candy—and the fireplace would seem to make an easy and obvious source of non-presents. All the individual would need to do is reach down into the fireplace and grab a lump of coal. (While many people think of fireplaces burning wood logs, coal-fired ones were very common during the 19th and early 20th centuries, which is when the American Santa mythos was being established.)

That said, with the exception of Santa, none of these characters limits himself to coal when it comes to bad kids. They’ve also been said to leave bundles of twigs, bags of salt, garlic, and onions, which suggests that they’re less reluctant than Santa to haul their bad kid gifts around all night in addition to the good presents.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Why Are Poinsettias Associated with Christmas?

iStock
iStock

Certain Christmas traditions never seem to go out of style. Along with wreaths, gingerbread cookies, and reruns of A Christmas Story sits the poinsettia, a red-tinged leafy arrangement that’s become synonymous with the holiday. Upwards of 100 million of them are sold in the six weeks before December 25.

Why do people associate the potted plant with seasonal cheer? Chalk it up to some brilliant marketing.

In 1900, a German immigrant named Albert Ecke was planning to move his family to Fiji. Along the way, they became enamored of the beautiful sights found in Los Angeles—specifically, the wild-growing poinsettia, which was named after Joel Roberts Poinsett, the U.S.-Mexican ambassador who first brought it to the States in 1828. Ecke saw the appeal of the plant’s bright red leaves that blossomed in winter (it’s not actually a flower, despite the common assumption) and began marketing it from roadside stands to local growers as "the Christmas plant."

The response was so strong that poinsettias became the Ecke family business, with their crop making up more than 90 percent of all poinsettias sold throughout most of the 20th century: Ecke, his son Paul, and Paul’s son, Paul Jr., offered a unique single-stem arrangement that stood up to shipping, which their competitors couldn’t duplicate. When Paul III took over the business in the 1960s, he began sending arrangements to television networks for use during their holiday specials. In a priceless bit of advertising, stars like Ronald Reagan, Dinah Shore, and Bob Hope were sharing screen time with the plant, leading millions of Americans to associate it with the holiday.

While the Ecke single-stem secret was eventually cracked by other florists—it involved grafting two stems to make one—and their market share dwindled, their innovative marketing ensured that the poinsettia would forever be linked to Christmas.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER