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
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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
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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 Are Barns Often Painted Red?

iStock/Ron and Patty Thomas
iStock/Ron and Patty Thomas

Beginning with the earliest American settlements and continuing into the 18th century, most barns weren't painted at all. Early American barn builders took sun exposure, temperature, moisture, wind, and water drainage patterns into account when placing and building barns, and they seasoned the wood (that is, they reduced the moisture content) accordingly. The right type of wood in the right environment held up fine without any paint.

Toward the end of the 1700s, these old-school methods of barn planning and building fell by the wayside. People sought a quicker, easier fix for preserving their barns—a way to coat and seal the wood to protect it from sunlight and moisture damage. Farmers began making their own coating from a mix of linseed oil (a tawny oil derived from the flax seeds), milk, and lime. It dried quickly and lasted a long time, but it didn't really protect the wood from mold and wasn't quite like the "barn red"we know today—it was more of a burnt orange, really.

Turning Red

The problem with mold is that it decays wood and, in large quantities, can pose health risks to people and animals. Rust, it turns out, kills mold and other types of fungi, so farmers began adding ferrous oxide (rusted iron) to the linseed oil mix. A little bit of rust went a long way in protecting the wood, and it gave the barn a nice red hue.

By the late 19th century, mass-produced paints made with chemical pigments became available to most people. Red was the least expensive color, so it remained the most popular for use on barns, except for a brief period when whitewash became cheaper and white barns started popping up. (White barns were also common on dairy farms in some parts of Pennsylvania, central Maryland, and the Shenandoah Valley, possibly because of the color's association with cleanliness and purity.)

Throughout Appalachia (a historically poorer region), many barns went unpainted for lack of money. In the tobacco regions of Kentucky and North Carolina, black and brown barns were the norm, since the dark colors helped heat the barn and cure tobacco.

Today, many barns are still painted the color traditionally used in a given region, with red still dominating the Northeast and Midwest.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

This story was updated in 2019.

Is There An International Standard Governing Scientific Naming Conventions?

iStock/Grafissimo
iStock/Grafissimo

Jelle Zijlstra:

There are lots of different systems of scientific names with different conventions or rules governing them: chemicals, genes, stars, archeological cultures, and so on. But the one I'm familiar with is the naming system for animals.

The modern naming system for animals derives from the works of the 18th-century Swedish naturalist Carl von Linné (Latinized to Carolus Linnaeus). Linnaeus introduced the system of binominal nomenclature, where animals have names composed of two parts, like Homo sapiens. Linnaeus wrote in Latin and most his names were of Latin origin, although a few were derived from Greek, like Rhinoceros for rhinos, or from other languages, like Sus babyrussa for the babirusa (from Malay).

Other people also started using Linnaeus's system, and a system of rules was developed and eventually codified into what is now called the International Code of Zoological Nomenclature (ICZN). In this case, therefore, there is indeed an international standard governing naming conventions. However, it does not put very strict requirements on the derivation of names: they are merely required to be in the Latin alphabet.

In practice a lot of well-known scientific names are derived from Greek. This is especially true for genus names: Tyrannosaurus, Macropus (kangaroos), Drosophila (fruit flies), Caenorhabditis (nematode worms), Peromyscus (deermice), and so on. Species names are more likely to be derived from Latin (e.g., T. rex, C. elegans, P. maniculatus, but Drosophila melanogaster is Greek again).

One interesting pattern I've noticed in mammals is that even when Linnaeus named the first genus in a group by a Latin name, usually most later names for related genera use Greek roots instead. For example, Linnaeus gave the name Mus to mice, and that is still the genus name for the house mouse, but most related genera use compounds of the Greek-derived root -mys (from μῦς), which also means "mouse." Similarly, bats for Linnaeus were Vespertilio, but there are many more compounds of the Greek root -nycteris (νυκτερίς); pigs are Sus, but compounds usually use Greek -choerus (χοῖρος) or -hys/-hyus (ὗς); weasels are Mustela but compounds usually use -gale or -galea (γαλέη); horses are Equus but compounds use -hippus (ἵππος).

This post originally appeared on Quora. Click here to view.

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