COLORS AND SHAPES OF STARS

 

HOW DO THEY MAKE THE BEAUTIFUL COLORS OF STARS?

The explosive charge at the center of the shell is made of black powder or flash powder (composed of potassium perchlorate, aluminum powder, and/or magnesium which, upon ignition, creates a violent explosion combined with a flash). The explosion sends the burning stars out in a particular pattern determined by the way the shell was packed by the shell maker - creating the colorful effect the crowd sees.

How to make various color of fireworks?

Do you recall an experiment called "flame reaction" from your chemistry class? It is that burned chemical compound including specific element, flaming up with particular color of each element. A color of fireworks applies to this "flame reaction". The stars of fireworks can be created by mixing  three main powders. It is a combustible material which promotes the oxidant and combustion by which the mixture and oxygen with which the color is put out are created.

 

 

HOW THE COLORS OCCUR

The colors of fireworks come from bright-burning metallic salts. In fireworks there are six common colors, made by adding a specific chemical compound.

White =  is produced by magnesium or aluminum or titanium 
Yellow =  by sodium salts 
Red = by strontium nitrate 
Green = by barium nitrate or chlorate 
Blue = by copper compounds 
Orange/Amber = by charcoal or other carbon or iron compounds

Deep blue and purple are the most difficult colors to create because they have a very narrow band on the color spectrum, requiring the chemical reaction to be absolutely perfect. In fact, the creation of a deep blue flame remains one of the great challenges to pyrotechnicians. However, blue and green are considered the most dangerous colors to produce.

 

 

 

DEEP YELLOW.......................................................................Sodium Salts

YELLOW........................................................................Calcium Carbonate

BLUE.....................................................................................Copper Oxide

SILVER.......................................................................................Aluminum

RED................................................................Calcium/Strontium Carbonate

CRIMSON.....................................................................................Strontium

GREEN.................................................................................Barium Nitrate

GREEN AND BLUE. ........................................................................Copper

ELECTRIC-WHITE................................................Magnesium and Aluminum

 

Chlorine compounds are used to intensify or brighten colors. Recent stars show a tendency to be more brighter than usual by using magnesium's etc. This has been achieved by mixing magnesium's, slight neutral tints like difficult pink and purple. Trail used for chrysanthemum-star puts out a little dark orange when charcoal burns by chiefly using black gunpowder. Compound is made of various kinds of powders and chemicals. Though more safe chemicals are used, this is the most careful and dangerous process to date. Pyrotechnicians use empty hands to mix the compounds so they can feel the condition of chemicals.

THE FORMULAS
There are only about 100 top fireworks manufacturers in the world. Each company's formulas are closely-guarded secrets. The chemical and powder recipes are often handed down through generations of families. The color, animation, sound and flight pattern of each shell depends on its design and on the blend of its chemical ingredients.

Changing color of stars after explosion is an original technology of the Japanese fireworks. This change is based on the structure of changing color star. Concentric sphere consists of some layers of powder which burn  another color each other. This type of star, called "multi coated star" is made of materials like a seed or ceramics grain in the center, and coated over with powder. This coating work is performed by "Star-rolling machine." while spreading and drying them over drying table under the sun after one powder layer grows more thick. It is then dried and coated with powder again. Each star is grown bit by bit up to final size. It takes about 17 days to finish twenty millimeters across petal stars used in twelve inch round shell.

MAKING STARS

Homogeneous completion is needed for size and quality of each produced stars for color change, and for bursting all at once. There are some methods of making stars. Multi coated star take great deal of time. A unique Japanese method is applied in it's creation. Pressed stars are popular in any foreign-made fireworks. It consists of one kind of powder, as it's easier than a coated star and it has the same quality.

 

STARS
Each shell is very carefully constructed in a fireworks factory. A chemist produces the powders and presses or rolls them into pellets called 'stars' which are spherical, cylindrical or cube-shaped. The diagram below shows the different types of stars made.

 

When lit, the stars produce a brilliant ball of fire. They are made with oxygen-rich components such as strontium nitrate, potassium perchlorate, potassium nitrate and potassium chlorate. The star contains both oxidizer and fuel. When the oxidizer burns with the fuel made of charcoal, titanium powder and aluminum powder or other metal or carbon-based mixtures, the reaction to the burning of both oxidizer and fuel creates the effect of color.

The shell maker assembles the stars within the shell casing, in a careful configuration that determines the height at which the star will be expelled and so as to produce any desired effects (such as the star being 
expelled in a particular shape such as a heart or circle).

(Photos and articles courtesy of Japan-Fireworks.com)