How Fireworks are Made


Warning:  This page is not a guide to making fireworks.  Fireworks are complex devices that require great care to make, not only so they perform properly, but also to avoid a potentially fatal accident.  The following information is to help readers learn more about how fireworks function by understanding how the devices are created.  For that reason, no specific chemical formulas are listed in this section.

ROLLING and PLUGGING TUBES

Fireworks tubes are made by rolling thick paper tightly around a former, such as a dowel.  Though they can be made by hand, most firework/tube factories use machinery to manufacture tubes.

 

Whenever tubes are used in fireworks, at least one end is always plugged with clay to keep both chemicals and burning gases from escaping through that end.  The tooling is always made of non-sparking materials such as aluminum or brass.  Clay is inserted into the tube and then consolidated with the rammer using a heavy object such as a mallet (or possibly a fruit cake).  A sleeve is sometimes used during the ramming process to prevent the walls of the tube from splitting or bulging.  This process is illustrated below.

AERIAL REPEATER

1.  To make a typical square-shaped repeater, several clay-rammed tubes are glued to each other in rows.  Often a "sandwich" is made by placing thin cardboard strips on either sides of the tubes for strength.

2.  Two holes are then drilled in each tube.  Small pieces of fuse are placed in the holes to rapidly transfer fire from tube to tube.

3.  Rows of tubes are glued on top of each other, and fuses are inserted to transfer fire between rows.

4.  The battery of tubes is then stood upright, and a small, measured black powder lifting charge is put into each tube.  After that, a small tube containing aerial effects (stars, whistles, hummers, etc.) is placed into each larger tube.  To see a cross section of what this looks like, click here.  Yes, I do have too much spare time.

5.  Finally, the bottom and sides of the repeater are covered in another layer of thin cardboard to hold it together, followed (usually) by plastic cellophane on top and a colorful label on the side.

 

 

FOUNTAIN

Fountains consist of a tube filled with composition with clay plugs on either end, one of which has a small hole in it (see below).  The hole, called a "choke", prevents the hot gas from escaping from the tube as easily as it would if there were no plug at all.  This builds up pressure inside the tube, and as a result escaping gas and sparks are shot up with a lot of force.  

The easiest way of making a choke is to build it directly into the fountain tube by compacting clay around a former known as a nipple.  Solid rammers are used to compress the fountain composition once it has been inserted into the tube.  Nipples usually have a sleeve that the tube fits in to prevent it from breaking when the composition is being rammed in.  All fountain tooling should be made of non-sparking materials such as aluminum, brass, or wood.

If you don't understand any of the stuff above, just scroll down and let my award-winning MS Paint drawings explain it to you visually.

PROCESS

1.  A tube is placed in the spindle/sleeve assembly and an amount of clay is added.
2.  The rammer with the small indent is used to compact the clay around the spindle, which leave create a hole when the tube is eventually removed.  The clay plug should always be as thick as the tube is wide.
3.  After the choke is formed, increments of fountain composition (the grayish stuff) are added in small increments and compacted with the solid rammer.  This process is repeated until the tube is nearly full.
4.  When little room remains at the top of the tube, more clay is added/compacted to make another plug.

5.  The tube is removed from the nipple/sleeve assembly and inverted.  It is then attached to a block of wood (see below) and a fuse is inserted into the choke.  Usually thin kraft "nosing paper" is pasted on the tube so that it overlaps the top end of the fountain, which serves to protect the fuse.

 

Multiple-tube fountains are becoming more and more common these days as consumer fireworks continue to get bigger and  better.  Such fountains aren't actually one unit, but consist of many fountains fused together within a large tube (shown at right).  In most cases, the outer casing is large enough to support the device without it needed any sort of base.

more coming soon!

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