Fireworks are meant to dazzle the eye and the mind with spectacular colors. The colors burst out into awesome shapes and are accompanied by extremely loud booms, bangs and whistles. By definition the word “firework” means: a device for producing a striking display by the combustion of explosive or flammable compositions. Fireworks are one of the few things today that were discovered by accident.

Fireworks have an interesting history; well actually they have many histories. The history of fireworks goes back thousands of years to the Han dynasty, about 200 B.C. long before gunpowder was invented. It is believed that the first “firecrackers” were chunks of green fresh cut bamboo were thrown onto fires when dry wood ran short. They began to burn nicely, but eventually they randomly exploded. What happened is that because bamboo grows so rapidly that pockets of air and sap are trapped inside the bamboo chute. And when the air is heated is expands, keep on heating it and pressure builds up in the bamboo until it explodes with a loud long crack!

Now for the gunpowder side of the story. The birthplace of fireworks is generally recognized as China, this belief has not been disproved. The way gunpowder was discovered is actually quite funny. A cook in a field kitchen supposedly discovered gunpowder accidentally; some time in the Song dynasty, about 960-1279 A.D. This cook had found that a mixture of sulfur, saltpeter and charcoal were very flammable when mixed together. (The funny part is that these 3 items were all common kitchen ingredients). Okay so it isn’t that funny, but it is odd. This crazy cook also discovered that it become explosive than confined in a small space and ignited. It is surprising that this field cook lived to tell the tale of the exploding substance. Now after sharing his discovery, other monks and cooks alike were experimenting with gunpowder a lot. They found that certain colors were created when other colors were added into the mix, and then ignited.

The Chinese developed rockets and used them to help defeat the Mongol invaders of 1279. Fireworks have had many uses over the hundreds of years since they have been created. The Chinese had many uses for it. Because fireworks were new to the world the loud booms and bangs were frightening to animals and humans. The Chinese figured that if it scared living creatures so much, it would probably scare away spirits, particularly an evil spirit called Nian, who they believed to eat crops and people. After that, it became customary for them to throw green bamboo onto a fire during the Lunar New Year in order to scare Nian and other spirits far way, thus ensuring happiness and prosperity to their people for the remainder of the year. Soon, the Chinese were using bursting bamboo for other special occasions, such as weddings, coronations, and births. The “bursting bamboo”, or pao chuk as the Chinese called it, along with simple firecrackers continued to be used at such events and are still used today. Today they aren’t as primitive as they used to be, but in one way or another the Chinese still use fireworks, or bamboo in celebrations.

Although gunpowder was discovered in china, the majority of the research and usage was happening in Europe. Germans were developing fireworks to use them in battles. The Italians were using fireworks to mark great occasions. Firework schools were established in Germany and Italy during the renaissance. The one in Italy emphasized elaborate fireworks while the one in Germany stressed scientific advancement. The British were using fireworks for all kinds of celebrations; even some people of the middle class were using them. Queen Elizabeth I loved fireworks so much she created a royal position for a professional firework maker: “The Fire Master of England” King James II liked the fireworks display at his coronation that he knighted his Fire Master. Black powder also enabled the development of rockets, cannons, and guns. But throughout all these developments, fireworks were still just a bright light in the sky; there really wasn’t that much color. This went on until around the 19th century, until pyrotechnicians started experimenting with metals.

Before the 19th Century, the only colors that could be produced were yellows and oranges with

Temperature (C)

Color

480

Faint Red

580

Dark Red

730

Red/Orange

930

Bright Orange

1100

Orange/Yellow

1300

Yellow/White

>1400

White

the use of steel and charcoal. Later development involved Chlorates that introduced basic reds and greens to the repertoire. Good blues and purples were not developed until this century and the quest for a deep forest green firework color is still going on. There are two ways to make a firework produce color: incandescence and luminescence. Incandescence is the light produced from heat. Heat causes the substance to grow hot and glow. This results in the emission of infrared rays, then moves up the spectra to white light spectra, which is visible to our eyes. But heating of a substance to produce light can only work to about the color orange. Then it becomes too hard to get any color further along the spectrum. Blues and greens require much higher temperatures and so cannot be formed using this method. Instead, they are created by Luminescence.

Luminescence is a process that is much easier to create a wide variety of colors, because lower temperatures are required. Elements all burn with a color unique all to themselves, so all that is needed is the right combination of elements to produce a spectacular color. Every element is made up of atoms of the same type this is why they burn in different colors. First the atom receives energy, either from heat or electricity, (in this case heat, because when gunpowder is ignited it explodes in a small fiery inferno). This heat causes the orbiting electrons to spin into outer orbits, but here, the electrons become unstable and try to return to their original orbits where they will be stable. When the electrons travel back to their original orbits they give off light energy, called photons. These photons emit light that is seen as one color, but if the light is separated through a crystal prism it forms colors of lines in the ultraviolet spectra. Each element has a unique light signature. Electrons can travel back to their original orbits in segment or all at once. Depending on the distance the electron travels; it gives off a photon that emits a certain color light. Pyrotechnicians use this information to decide which element to use to produce to color they want. Because some elements constantly produce photons that have the same energy, thereby always giving a constant color. The color of light directly corresponds to the energy in the photon. From least energy to greatest energy, the colors in the spectrum are as follows: red, orange, yellow, green, blue, violet.

The after about a hundred years of experimenting with elements, pryotechnicians and firework manufacturers use these elements:

Aluminum produces sliver and white flames and sparks, which gives sparklers their dazzling effect. Barium produces green and has no other effects. Carbon is used in black powder, so it is a very important element. Calcium is used to enhance the color of fireworks, to give it a deeper color; calcium salts produce orange color. Copper produces blue. Iron is an interesting element, it produces little sparks, the color of iron is variable. Depending on the temperature of the metal, the color changes accordingly, red being the coolest, and yellow and white being the hottest. Potassium produces a purple or violet flame and is important in black powder. Lithium produces red. Magnesium produces a very bright white light; it is commonly used with iron to make pleasing white sparks. Sodium produces a gold-yellow color, it is used in moderation because it is very bright and can mask other less intense colors. Because phosphorus burns spontaneously in air is responsible for glow in the dark effects of the light. It is also a component of black powder. Sulfur is a component of black powder. Antimony produces a firework’s glitter effects. Strontium produces red. Titanium can be burned as powder or flakes to produce silver sparks. And last but not least, Zinc produces smoke effects for firework displays.

There are many types of fireworks, all with a unique purpose and different way of launching the firework. A normal aerial firework is composed of a base on the bottom. The mortar tubes angle the charge in the direction that is desired and then the life charge is placed in the bottom then fused. The firework is then placed in the tube and then a protective cardboard disk is placed on top sealing the firework inside. Then a paper cap is put on the mortar tube to ensure no dust can get in the mortar tube.

Firecrackers are the simplest and oldest of fireworks. A single firecracker is simply a paper tube of several layers to give it strength. It is plugged at both ends with a dry clay-like substance, and contains a small amount of flash powder in the middle. When the fire from the fuse ignites the flash powder, it creates a large volume of hot gas in a short period of time. The casing of the tube contains this gas until the pressure blasts the tube open with a loud “crack”.

Single tube fountains consist of a cardboard tube (which may be inside of a cone) that stands vertically on a plastic base. The tube is charged with a composition designed to make lots of sparks, flame, and gas. At the end of the tube there is a clay plug with a hole drilled into it, forming what is known as a “choke”. Without a choke, the fountain would only give off a weak spray of sparks. With a choke, however, a lot of pressure builds up inside of the tube, which forces the gas and sparks out of the fountain with a much greater velocity. Very small fountain tubes (i.e., 1/4 in diameter) don’t require chokes. The fountain composition is often layered as to produce different effects at different stages in the burning. For instance, one layer may burn to produce orange sparks, followed by a layer that produces white sparks and green star fragments.

Strobes are usually small paper cups filled with a liquid composition that is allowed to dry. Strobe composition is a mixture that consists of two main parts: a composition that reacts easily, and one that doesn’t. When the fuse ignites the composition, the more reactive compound burns to create a large amount of heat. This heats up the more difficult to ignite portion of the mixture, which goes off with a sudden flash once it reaches ignition temperature. This process repeats itself over and over, gradually increasing in frequency and producing hundreds of flashes. In display fireworks, strobe composition is made into stars and put into either aerial shells or mines.

The most famous smoke device is probably the smoke bomb, a large ball of clay with a hollow center. Inside the center is a composition that usually consists of potassium chlorate, lactose, and a powdered dye. When ignited, this composition burns at a relatively low temperature, which evaporates the dye into fine particles and disperses them into the air (so the colored “smoke” isn’t actually smoke at all). The smoke composition must be cooled off fairly quickly after ignition, or else the dye particles will react with oxygen to burn up. This is why smoke is always observed rapidly exiting the burning chamber. If you hold a smoke device too close to a solid object, the burning particles can’t get away fast enough to cool down. At this point, the device will begin emitting a flame rather than smoke.

Though roman candles seem like a simple firework, the construction process is quite complex and difficult. After a clay plug at the bottom, the Roman candle tube consists of alternating layers of lift charge, stars, and delay compositions. When the fuse enters the tube, it activates a slow-burning delay composition that makes its way down. Within seconds, the delay charge reaches the first star, simultaneously igniting both it and the lift charge below it, which blows the star out of the tube. This ignites another layer of delay composition, which will light a star and the lift charge to blow it out a few seconds later. This continues until every star has been blown out of the tube. These are illegal in California.

The physics of fireworks are relatively simple. Just follow these equations:

H=V1T+.5G^2

H=height, V1=initial vertical velocity, T=time, G=gravity which is approximately 10m/sec^2.

Z=V2T

Z=horizontal distance, V2=initial horizontal velocity, T-time.

Shell Size, (in inches)

Initial Velocity (in ft/sec)

2”

117.5

3”

144

4“

166

5“

186

6“

203.5

8“

235

10“

263

12“

287.5

24“

393

36“

481

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