Burns Fireworks - Display

Touchy chemistry

-- First, you need to have a firm grasp on the physics and
chemistry behind these rising stars.

Aerial fireworks have two main components, the shell and the mortar. The shell holds all of elements that colour the sky and the mortar acts like a cannon, launching the shell into the air.

Professionals use mortars made out of fibreglass or heavy plastic H.D.P.E. to cope with the heat generated by the explosives.

The source of that heat is black powder, a highly reactive mixture of nitrates (often potassium or ammonium nitrate), carbon and sulphur better known as gunpowder. When you light the fuse on a firework, the flame travels to the black powder located at the base of the shell. The black powder combusts: nitrate molecules give up oxygen atoms to the carbon and sulphur. All that combustion creates a lot of pressure inside the mortar, which forces the shell to rocket into the air.

But fireworks have that all-important, next step. When the black powder launches the shell, it also ignites the shell's own fuse. As the shell hurtles through the air, the fuse burns until it ignites more black powder inside the shell.

Again, the powder combusts and pressure builds. This time, that pressure is used to burst the shell and scatter the stars.

In the fireworks industry, the term star refers to a small ball of compounds that create the colour in a fireworks display.

At the time of manufacture, many stars are carefully packed into a single shell and surrounded by black powder. The placement of the stars determines the final appearance of the controlled explosion. To make a ring shape in the sky, stars might be placed around the outer rim of the shell with black powder in between.

The explosion of black powder also ignites the stars, so that they begin to burn as they careen through the air. That's when we see them as colourful flashes of light in the sky.

The colour produced depends on the composition of the stars.

Stars that burn red are typically made with strontium salts, while green stars use barium salts.

Gold stars are made with iron or iron titanium alloys. Blue hues use copper salts. White comes from antimony, or aluminium powder.

Those colours wouldn't appear without the energy generated in that final explosion of black powder. The star's molecules absorb the added energy, exciting the orbiting electrons. The electrons get so excited, in fact, they move further away from the rest of their respective molecules. They hop from one energy level, or orbit, to another.

It's a short trip, however, because the electrons quickly fall back into their original orbit and throw off their extra energy in the form of coloured light.

The amount of energy that is released depends on the kind of atoms that make up the molecule. Each colour corresponds to quantity of energy.

It's quite the miraculous little chain of events, when you think about it,

Hand Firing

First and foremost "Inspect your equipment"
All equipment must be in the best condition

Where possible bury the mortars in the ground to 3/4 their length. If the ground is too hard or not available, sand boxes can be used All mortars should be in place before the display. Angle mortars as Illustrated, away from spectators.

Make sure the top of the shell with the quickmatch is up. When the shell is being loaded it should slide freely to the bottom.

The bottom of the shell should rest at the base of the mortar. Do not try to force the shell to the bottom of the mortar. Do not remove the safety cap at the end of the quickmatch until you are ready to fire the shell.

Portfire and portfire holder should be used for igniting the quickmatch. Remove the safety cap just prior to ignition, only on the shell you are firing, all other safety caps must remain on. If a shell fails to ignite, do not approach it for at least 30 minutes

Matched Shells ( Flight )

Groups of shells can be joined with quickmatch and fired together. Load as Illustrated.

Low Level

Mines & Candles

Stabilize the mines & candles by burying half their length in the ground. They can be angled 10 to 15 degrees away from spectators as illustrated in the picture above. Or, they can be angled straight up and down if site and distance permits. The preferred angle is straight up and down. Mines & candles can be connected with quickmatch and fired simultaneously, or connected with squibs and fired electrically.

Wheels

The units must be attached in a horizontal or vertical position to an upright wooden support. Nail the wheel to the wooden support. Make sure you allow plenty of freedom for movement. These units can be fired singly or in multiples.

Fans

These units can be assembled at ground level, or can be attached to wooden uprights as illustrated. The preferred method for simultaneous firing of more than one cluster is electric as illustrated above. Average spacing between clusters is 20 to 30 feet.

Candles

Individual candles can be attached to wooden uprights. These units are attached with quickmatch for simultaneous firing when the main fuse is lit. If more than one group of candles is used, the preferred method of firing is electric as illustrated above. Average spacing between groups is 20 to 30 feet.

Electric match

--In pyrotechnics, an electric match is a device to ignite the end of a fuse under control of an externally applied electrical current. They are widely used in professional fireworks displays to control firing from a panel of manually-operated switches, or from a computer interface.

--E-matches, or electric matches, are used by professionals to light fireworks from a safe distance.

At the tip of the match, where the two wires meet, is a special material called nichrome that's highly resistive to electricity.

"It's the same kind of wire in your toaster," The ends of the wires also are connected to a battery and the whole circuit is controlled by a switch. Flip the switch and energy from the battery travels down one of the wires into the firework, where the match's nichrome tip comes in contact with the black powder. The electricity wants to flow through the nichrome to the second wire and complete its route through the electric circuit. But it's partly held back by the resistive forces of the nichrome.

The more electricity the nichrome resists the hotter it gets. It doesn't take long before the black powder ignites from the heat and the fireworks begin.

"It does provide added safety for pyrotechnic crew because they are not near the fireworks when they go off," "Electric matches also allow the show to be fired with much greater precision."

Some fireworks companies still control the switches manually.

A computer called a field controller manages the show. It sends signals to various modules that, in turn, send electric signals to the e-matches. Software lets you co-ordinate the explosions with music. The sounds and signals are all saved in one electronic file.

For a three-minute show, you might use 1,700 shells. Imagine lighting that many by hand, at precisely the right moment!

Some in the industry envision a future where fireworks are also controlled by onboard sensors, to determine when and if they should detonate.

If a shell accidentally flies off into the audience, sensors reading its location could stop it from exploding.

Squib

--A squib is a small explosive device which has a wide range of uses, such as generating mechanical forces as well as in pyrotechnic use. A squib can range in size from a small cap only millimeters in diameter to ones which can be 15 millimetres in diameter. The squib, being an explosive device, releases a lot of energy, and can be used for shattering, triggering, propelling and cutting a wide range of pyrotechnic and non-pyrotechnic materials.

It must be distinguished from a detonator, which is used specifically to initiate high explosive. A squib may indeed be energetic enough to initiate high explosives, but that is not its primary purpose.

It must also be distinguished from the electric match, which produces only a flash of flame and is used to ignite military simulation pyrotechnics, stage pyrotechnics, fireworks in professional firework shows, charges for special effect purposes, rockets and a wide range of other pyrotechnic items requiring merely flame to ignite them.

In aviation, squibs are used to generate pressurised gas to open valves and operate small mechanical devices such as those found on ejection seats, and to pierce metal diaphragms that are retaining pressurised liquids such as halon and fluorocarbon extinguishants, or release compressed nitrogen gas to act as a propellant.

They are widely used in the special effects industry to simulate a bullet hit by coupling the squib itself with a condom or balloon of either fake blood for hits on persons or dust/debris for hits on other objects.

Squibs may be sensitive to EM radiation and devices such as vehicle radios, radar, cellular and microwave transmitters can set off a squib unless the two leads are terminated correctly, or better still, are fitted with suppressing ferrite filters.

Cellular phones have never been implicated in the initiation of explosives by direct radiation from the aerial to an igniter. Despite this, there are several urban legends surrounding the sensitivity of squibs.

Squibs were originally made from parchment tubes, or the shaft of a feather filled with fine black powder and sealed at the ends with wax. These were inserted into the touch holes of cannon and used to ignite the main propellant charge. Roger Bacon first described the making of squibs in 1248.

A "damp squib" is literally one that fails to go off due to wetting, but the term has come into general use to mean anything that fails to meet expectations.

Squibs are also used in many movies along with blank firing guns. A condom is filled with fake blood and other chunks of sponge are used to thicken it up. The blood pack is placed on a squib and when it is remotely triggered the blood pack explodes, giving off a realistic looking gun shot with blood flying out of the wound.

Fuse

--The simplest fuse is a length of combustible material which burns from the free end, through a small opening in the casing, and into the device, where it then ignites the bulk material. The fuse thus works to pass fire from the user to the device, which separates the user from the action with both distance and a time delay. Fuses are found in fireworks, model cannons, antique smoothbore firearms, some improvised explosive devices and many forms of pyrotechnics.

A key feature of a pyrotechnic fuse is that it burns steadily using self-contained fuel and oxidizer. This allows it to reliably burn along its entire length at a controlled rate. Fuses with unpredictable burning rates, or that self-extinguish, create hazards in pyrotechnics. The self-containment also passes fire through tight passages and into confined spaces where no air is present.

Fuse is made in various forms:

Consumer fireworks typically use a small length of Visco fuse, a black powder cored fuse wrapped twice with string and waterproofed with nitrocellulose lacquer, or paper tissue coated with black powder and rolled to keep the black powder in the center.

Larger fireworks, some commercial applications, and model cannons usually use a fuse which has a core of grains of black powder, wrapped in a sheath of cloth (usually cotton) fibers and then coated with a lacquer, shellac, or more modern protective coating.

Fuse for blasting (also known as safety fuse), is a larger diameter (typically 1/4 inch or 6.25mm) higher energy, more solidly protected cloth fiber wrapped black powder core fuse. Safety fuse fits into the opening at the end of a pyrotechnic or fuse-ignited blasting cap and is crimped into place. Pyrotechnic blasting caps are still the most common form of detonator used for commercial and military explosives worldwide.

Some safety fuse has an outer layer of plastic around the cloth and black powder. This fuse can burn reliably underwater once lit.

Slow match is a very slow-burning fuse consisting of a hemp or cotton rope saturated with an oxidizer such as potassium nitrate. Slow match is used as a source of fire for manually lighting other devices, such as matchlock guns, or fuses on black powder cannons. Before percussion caps, slow match was most suitable for use around black powder weapons because it could be roughly handled without going out, and only presented a small glowing tip instead of a large flame that risked igniting powder supplies nearby.

Today's punks (wood splints covered with ground plant pith saturated with nitrate) used for lighting consumer fireworks are a type of slow match.

Black match is a type of fuse consisting of cotton string coated with a dried slurry of black powder and glue. This acts as a simple pass-fire, and was used to fire ancient cannons. It is used today in fireworks construction.

Quick match or piped match is a type of black powder fuse that burns very quickly, some hundreds of feet per second. It consists of black match covered with a loose paper wrap (pipe). When lit, the flame propagates quickly down the paper pipe from the hot gases produced by the burning powder. Quick match is used in professional fireworks displays to pass fire nearly instantly between devices that must be physically separated while firing simultaneously, such as a finale rack. Devices which should fire in sequence can be branched from a single master fuse, consisting of quick match spliced onto Visco fuses of various length for time delays.

An electric match lights a main fuse or device when activated by an electrical current. They typically consist of a pair of wires leading to a thin resistance wire that heats when current is applied. The resistance wire is covered by a bit of pyrotechnic composition that ignites from the wire heating, providing enough fire to reliably ignite the main fuse via a mechanical connection, or the device directly. Estes model rocket motors are lit by a type of electric match. Large fireworks displays are launched with complex timing sequences using a computer that energizes electric matches connected to the individual device fuses.

Flying fish fuse is an unusual type of component for fireworks. It is made like Visco fuse, but contains a metallic spark composition or other effect instead of black powder. Flying fish can thus perform as a main effect instead of just an initiator. For example, simply lighting a short piece of flying fish on the ground makes it fly through the air, seeming to swim in random directions, while emitting sparks and noise. A aerial shell loaded with many such pieces results in a beautiful myriad of pieces flying and sparking high in the air.

A spoolette is a delay fuse consisting of a hollow wooden dowel rammed full of black powder. A spoolette is glued into the wall of a fireworks shell and ignited by the lift charge that launches the shell into the air. The spoolette, after a delay that allows the shell to reach its top of trajectory, ignites the shell's main effect(s). The tough wood construction ensures that the fuse burns reliably despite the explosive force and acceleration of the launch.