Fireworks

Fireworks are low explosive pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays, combining a large number of devices in an outdoor setting. Such displays are the focal point of many cultural and religious celebrations, though mismanagement can lead to fireworks accidents.
Fireworks take many forms to produce four primary effects: noise, light, smoke, and floating materials. They may be designed to burn with colored flames and sparks including red, orange, yellow, green, blue, purple and silver. They are generally classified by where they perform, either 'ground' or 'aerial'. Aerial fireworks may have their own propulsion or be shot into the air by a mortar.
Most fireworks consist of a paper or pasteboard tube or casing filled with the combustible material, often pyrotechnic stars. A number of these tubes or cases may be combined so as to make when kindled, a great variety of sparkling shapes, often variously colored.
A skyrocket is a common form of firework, although the first skyrockets were used in warfare. The aerial shell, however, is the backbone of today's commercial aerial display, and a smaller version for consumer use is known as the festival ball in the United States.
Fireworks were originally invented in China. China remains the largest manufacturer and exporter of fireworks in the world.

History

The earliest fireworks came from China during the Song dynasty. Fireworks were used to accompany many festivities. In China, pyrotechnicians were respected for their knowledge of complex techniques in creating fireworks and mounting firework displays.
During the Han dynasty, people threw bamboo stems into a fire to produce an explosion with a loud sound. In later times, gunpowder packed into small containers was used to mimic the sounds of burning bamboo. Exploding bamboo stems and gunpowder firecrackers were interchangeably known as baozhu or baogan. During the Song dynasty, people manufactured the first firecrackers comprising tubes made from rolled sheets of paper containing gunpowder and a fuse. They also strung these firecrackers together into large clusters, known as bian or bianpao, so the firecrackers could be set off one by one in close sequence. By the 12th and possibly the 11th century, the term baozhang was used to specifically refer to gunpowder firecrackers. The first usage of the term was in the Dreams of the Glories of the Eastern Capital by Meng Yuanlao.
During the Song dynasty, common folk could purchase fireworks such as firecrackers from market vendors. Grand displays of fireworks were also known to be held. In 1110, according to the Dreams of the Glories of the Eastern Capital, a large fireworks display mounted by the military was held to entertain Emperor Huizong of Song. The Qidong Yeyu states that a rocket-propelled firework called a dilaoshu went off near the Empress Dowager Gong Sheng and startled her during a feast held in her honor by her son Emperor Lizong of Song. This type of firework was one of the earliest examples of rocket propulsion. Around 1280, a Syrian named Hasan al-Rammah wrote of rockets, fireworks, and other incendiaries, using terms that suggested he derived his knowledge from Chinese sources, such as his references to fireworks as "Chinese flowers".
Colored fireworks were developed from earlier Chinese application of chemical substances to create colored smoke and fire. Such application appears in the Huolongjing and Wubeizhi, which describes recipes, several of which used low-nitrate gunpowder, to create military signal smokes with various colors. In the Wubei Huolongjing, two formulas appears for firework-like signals, the sanzhangju and baizhanglian, that produces silver sparkles in the smoke. In the Huoxilüe by Zhao Xuemin, there are several recipes with low-nitrate gunpowder and other chemical substances to tint flames and smoke. These included, for instance, arsenical sulphide for yellow, copper acetate for green, lead carbonate for lilac-white, and mercurous chloride for white. The Chinese pyrotechnics were described by the French author Antoine Caillot : "It is certain that the variety of colours which the Chinese have the secret of giving to flame is the greatest mystery of their fireworks." Similarly, the English geographer Sir John Barrow wrote "The diversity of colours indeed with which the Chinese have the secret of cloathing fire seems to be the chief merit of their pyrotechny."
Fireworks were produced in Europe by the 14th century, becoming popular by the 17th century. Lev Izmailov, ambassador of Peter the Great, once reported from China: "They make such fireworks that no one in Europe has ever seen." In 1758, the Jesuit missionary Pierre Nicolas le Chéron d'Incarville, living in Beijing, wrote about the methods and composition of Chinese fireworks to the Paris Academy of Sciences, which published the account five years later. Amédée-François Frézier published his revised work Traité des feux d'artice pour le spectacle in 1747, covering the recreational and ceremonial uses of fireworks, rather than their military uses. Music for the Royal Fireworks was composed by George Frideric Handel in 1749 to celebrate the Peace treaty of Aix-la-Chapelle, which had been declared the previous year.
"Prior to the nineteenth century and the advent of modern chemistry they must have been relatively dull and unexciting." Bertholet in 1786 discovered that oxidations with potassium chlorate resulted in a violet emission. Subsequent developments revealed that oxidations with the chlorates of barium, strontium, copper, and sodium result in intense emission of bright colors. The isolation of metallic magnesium and aluminium marked another breakthrough as these metals burn with an intense silvery light.

Pyrotechnic compounds

Colors in fireworks are usually generated by pyrotechnic stars—usually just called stars—which produce intense light when ignited. Stars contain four basic types of ingredients.

A fuel
An oxidizer—a compound that combines with the fuel to produce intense heat
Color-producing salts
A binder which holds the pellet together.

Some of the more common color-producing compounds are tabulated here. The color of a compound in a firework will be the same as its color in a flame test. Not all compounds that produce a colored flame are appropriate for coloring fireworks, however. Ideal colorants will produce a pure, intense color when present in moderate concentration.
The color of sparks is limited to red/orange, yellow/gold and white/silver. This is explained by light emission from an incandescent solid particle in contrast to the element-specific emission from the vapor phase of a flame. Light emitted from a solid particle is defined by black-body radiation. Low boiling metals can form sparks with an intensively colored glowing shell surrounding the basic particle. This is caused by vapor phase combustion of the metal.
The brightest stars, often called Mag Stars, are fueled by aluminium. Magnesium is rarely used in the fireworks industry due to its lack of ability to form a protective oxide layer. Often an alloy of both metals called magnalium is used.
Many of the chemicals used in the manufacture of fireworks are non-toxic, while many more have some degree of toxicity, can cause skin sensitivity, or exist in dust form and are thereby inhalation hazards. Still others are poisons if directly ingested or inhaled.

Common elements in pyrotechnics

The following table lists the principal elements used in modern pyrotechnics. Some elements are used in their elemental form such as particles of titanium, aluminium, iron, zirconium, and magnesium. These elements burn in the presence of air or oxidants. Most elements in pyrotechnics are in the form of salts.

Symbol	Name	Fireworks usage
Al	Aluminium	Aluminium metal is used to produce silver and white flames and sparks. It is a common component of sparklers.
Ba	Barium	Barium salts are used to create green colors in fireworks, and it can also help stabilize other volatile elements.
C	Carbon	Carbon is one of the main components of black powder, which is used as a propellent in fireworks. Carbon provides the fuel for a firework. Common forms include carbon black, sugar, or starch.
Cl	Chlorine	Chlorate and perchlorates are common oxidizers.
Cu	Copper	Copper compounds produce blue colors.
Fe	Iron	Iron powder is used to produce sparks in sparklers.
K	Potassium	Potassium nitrate, potassium chlorate, and potassium perchlorate are common oxidizers. The potassium content imparts a faint violet color to the sparks.
Mg	Magnesium	Magnesium metal burns a very bright white, so it is used to add white sparks or improve the overall brilliance of a firework.
Na	Sodium	Sodium imparts a gold or yellow color to fireworks; however, the color is often so bright that it frequently masks other, less intense colors. Sodium lamps operate with the same optical emission.
O	Oxygen	Oxygen is a component of chlorate and perchlorate, common oxidizers.
S	Sulfur	Sulfur is a component of black powder, and as such, it is found in a propellant/fuel.
Sr	Strontium	Strontium salts impart a red color.
Ti	Titanium	Titanium metal can be burned as powder or flakes to produce silver sparks.
Zr	Zirconium	Zirconium, like titanium, burns to produce oxides that emit brightly. It is used in "waterfalls".