Today we remember the 5th November.
When, in 1605, a group of rebel conspirators failed to assassinate the King, a national holiday was born. Now known as Guy Fawkes or Bonfire Night, the anniversary of this foiled plot is marked across the British Isles by fireworks and bonfires.
And Bonfire Night isn’t the only glamorous event of the week. This year, another festival of lights coincides with the annual display. Diwali – a 5-day long Hindu celebration – falls between the 3rd and 7th November 2013.
With the combination of these two blazing commemorations, tonight is sure to go out with a bang. But what exactly is a firework, and why do they look so pretty?
Fireworks were invented in China in the 7th century. There are several types of fireworks and each one functions in a slightly different way.
Firecrackers are the original, simplest type of firework. They consist of gunpowder (or “black powder”), wrapped in paper, containing a fuse that is used to light the device.
The gunpowder itself is made of three components:
- Potassium Nitrate (KNO3), which acts as an oxidiser
- Carbon in the form of charcoal or sugar, which provides the fuel
- Sulfur, which stabilises the reaction
When the fuse is lit, energy is given to the gunpowder. Carbon from the fuel combines with oxygen to form Carbon Dioxide (CO2). The reaction also produces Nitrogen gas (N2) and Potassium Sulfide. The expanding Nitrogen and Carbon Dioxide gases increase the pressure inside the paper. As the pressure increases, the gases push on the wrapper until it explodes with a loud bang.
Sparklers are designed to give a different effect. A sparkler is a chemical mixture that has been molded onto a stick. They are made to burn slowly with a bright light. A sparkler is made of:
- Metal flakes
The fuel and oxidiser used to make a sparkler are often the same as in gunpowder, though recipes can vary. The additional binder is usually sugar or starch, while the metal powder helps to create the characteristic fiery sparks. To assemble a sparkler, the ingredients are mixed with water, forming a slurry. This is then coated over a wire or stick. Once dry, the sparkler is complete. To ignite, simply light at one end and the sparkler will burn in a shower of light.
Aerial Fireworks are arguably the most iconic class of firework. The displays are fired into the air and explode in the sky. An aerial firework is made of a shell that has four parts.
- The container – paper and string molded into shape
- Stars – spheres, cubes or cylinders packed inside the firework, similar to sparklers
- Bursting charge – gunpowder which lies at the heart of the firework (like in a firecracker)
- Fuse – provides a time delay before ignition
The main difference between a firework and a firecracker is that gunpowder in a firework is used to propel the rocket forwards. To achieve this, there is a hole at the bottom of the container. This allows the expanding gases to escape and launch the rocket into the air. The way the components – the bursting charge and the stars – pack into the shell determines the shape of the firework.
To alter the colour of a firework, different chemical compounds are added. Examples of colourants added to fireworks include:
- Lithium salts (Red)
- Calcium salts (Orange)
- Copper Chloride (Blue)
- Sodium Nitrate (Yellow)
- Barium Chloride (Green)
With the right ingredients, it is even possible to make fireworks at home (see this guide for a how-to), so there is no need to spend masses of money to enjoy pyrotechnics!
It has now been over 400 years since the failed plot to blow up the houses of parliament. Nevertheless, November 5th remains fixed as a night of celebration. Generations have stood together on this night to gaze up at the heavens. Over time, we have perfected the art of the firework display. By tweaking recipes and altering shapes, we can now expect a spectacular display every November, worthy of the phrase “Remember, Remember …”