We will show you the construction of a 4" aerial 'Smiley Face' shell.
Not a very difficult shell to build, and a real cool effect in the night sky.
Photo was emailed to us. We do not know its origin.
The process below will work for most shells 3" through 8" in size. Shells that
are larger or small than this require a little different treatment. (We will
either add this information to the bottom of this page or come up with an
additional page.)
Plastic and paper cases can be used to build aerial shells. Plastic shells will leave
hard sharp pieces and parts around the area of the firework show. Paper will leave trash around
too, but the heavy paper is "eventually" biodegradable whereas the
plastic is not. A professional will pick up all trash after every firework show,
whatever the trash may be.
We will use
plastic here to keep things easy for you to see and understand. Paper
shells are a more difficult and a longer process to build. If you have
everything ready before hand, numerous plastic ball shells can made during the
day and shot off that same night.
Pictured below are plastic ball shells from 8" down to 7/8". In the front are
fuse collars and the top rings/eyelets. The shells are sitting
on 4", 3", 2" and 1" paper and plastic salute canisters.
Below are assembled and ready to go 3", 4", 6", and 8" ball shells. These are
examples of paper shells. The protrusions you see at the top of the 6 and 8" shells are
rising tails. The 8" shell has three tails attached to the top.
Start the building process by hot gluing the fuse collar on the lower half of
the shell, if a collar is necessary. The collar comes with larger shells. The
collar helps prevent the lift charge fire from reaching the inside of the shell
and setting off the firework inside of the mortar tube.
NOTE: Time fuse is a type of fuse that burns only on the inside with no
fire exposed, or leaving the sides of the fuse. This way it can pass through the
explosive composition in a firework shell and not cause it to go off. The fire
from the time fuse will only "spit fire" when it reaches the end of the fuse.
Timing is set by the time fuse length. Time fuse usually comes in 1/4"
thickness, which we will use here.
Second is hot gluing the time fuse into place. Good time fuse burns consistently
at 3 seconds per inch. For shells 3" through 8" a burn time of 3 seconds will
work for the average weight shell. This means that the fuse should be about
1-1/2" long, allowing for cross-matching of the fuse. (Cross-matching will be
covered below.)
The timing of the shell burst with the time fuse is very important. The shell
will rise into the air, slow, stop, and then start back down. A perfectly timed
shell will break (explode) just as it stops in the air. It will not break on the
way up or on the way down. Depending upon the shell and its effect you will have
to adjust the length of the time fuse to get the burst to happen at the proper
time.
The first photo below is gluing on the fuse collar. Some shells will not come
with a fuse collar. We use Zylene in which old shell pieces and parts have been
allowed to completely dissolve. This makes a somewhat thick glue that sets up
hard in a short time.
The second photo is of the time fuse being hot glued to the shell on the
outside. Both the inside and outside of the shells time fuse should be hot melt
glued. It is hard to hot glue the inside of small shells. In the latter case,
and in any case, insure that there is a continuous bead of glue covering the
fuse attaching it to the shell. If not the pressure and fire from the lift
charge could leak around the fuse or blow the time fuse into the shell causing
the shell to go off in the mortar tube or on the way up just a few feet outside
of the mortar, which are very dangerous situations. We use a magnifying glass to
inspect each and every shell, inside and out, before the shell building process
continues.
PHOTO -- PHOTO fuse collar and then time fuse being hot glued
Cross-matching is basically the process of insuring that the time fuse ignites
with the lift charge, and then that the time fuse ignites the burst charge
inside of the shell. For the inside of the shell it is of great importance where
the fire starts from the time fuse. If the fire starts in the bottom of the
shell, it will project the stars more toward the top when the shell breaks. It
is important that the burst charge be started from the very center of the shell
for a good break and a good looking symmetrical effect.
There are numerous ways to accomplish cross-matching both inside and outside of
the shell. Cross-matching the outside will be covered further on down. This is
one of the last steps in the shell building process. For the inside of this
shell, and most other shells of the 3" to 8" size, we poke a hole 1/4"
down into the center of the time fuse and fill the hole and coat the end of the
time fuse with a hot pyrogen mix. (See below for more information on pyrogen.)
We then take a plastic tube,
designed for this purpose, and place it over the time fuse. (Some drinking
straws are of the right size too.) We then hot glue
this tube to the shell and over the fuse as shown below. We cut these
plastic tubes to size before hand, but if it is not, we insure that the tube is
cut off "just below" the level of the shell half top. This tube is now filled
with 7FA or Meal-D Black Powder, some other powders and pyrotechnic compositions will work too. An extremely fast
burning powder/composition is needed to "basically" start a fire in the entire tube at the
same time. This tube is capped off with paper and/or glue to hold in the Black Powder
or composition used inside.
PHOTO flash tube over time fuse glued inside shell
We then fill both halves of the shell with meal coated rice hulls. This is rice
hulls coated with meal powder. Meal powder is finely granulated Black Powder
also known as Meal-D. Meal powder is stuck/glued to wetted rice hulls and
allowed to completely dry before use. It takes about 5 pounds of meal powder to coat 1
pound of rice hulls and the hulls then take days to dry.
The shell halves should be filled with coated rice hulls to the very top of each one, but not above the
rim. If you will notice, one shell fits inside the other. This is okay as when
the halves are placed together this will make for a tight fit to insure that the
stars that will be placed inside will not move around.
We can explain this all day long, so study the photo below, after reading this
description. Place stars around the outer edge of the lower shell
half slightly pushing them down into the meal coated hulls. Keep the stars
aligned with the outer edge of the shell. Then put the eyes
and smiling mouth stars in the shell as shown below. Be as precise with this as
possible. Any star that is out of place will be very pronounced when it is seen
lighting up in the night sky. (On this same note DO NOT try to place a star for
the nose! The star in the very center of the shell will never look right in the
air.) We have white glued the stars to a
tissue paper "frame" to hold the stars in place for mass production. The very light tissue paper
will burn away without notice in the air, and if you only used a tiny drop of
glue it will not effect the burning performance of the stars. Either way will
work if the shell is full enough to not let the stars move around when the shell
is moved or dropped after it is completed.
PHOTO stars placed in design in hulls -- stars on tissue paper holding them in
place too
The next step is the hardest part! Putting the two shell helves together without
spilling the contents or screwing up the Smiley Face design, or any other
effect that you may have in the shell. Okay! I'm a Missouri Hard Headed Hillbilly and you will have to "show
me" that placing a piece of cardboard between the two shell halves will help
line them up for assembly. I've never gotten this to work properly. The best way for us is to hold the two halves
together with the lips touching. Then quickly and suddenly flip the two halves
together. As hard as this sounds, it is not difficult after a few tries, and
most people get it right the first time.
The larger shells have a hole in the top for a hook. This type of shell will go
together easier as the air inside the shell has a place to go. Smaller shells do
not have this hole and will have to be held in place while the air escapes. If
you release the shell and it starts pushing itself apart you will need to hold
it a little longer, or place it in a jig with weights on it. We will not go into the
latter "jig" process here, but it is the best way if you are mass producing
shells.
PHOTO (moving) flipping shell halves together
Gluing the halves together, with the Zylene glue mentioned above, is done over a
tray or newspaper for easy clean up. Lay the shell on its side being very
careful with the time fuse sticking out of the bottom. DO NOT GET GLUE ON THE
TIME FUSE!!!! Slightly open the shell rim just enough to expose the lip, and
working around the lip using a Q-Tip or stick apply the glue to the 'entire'
inside lip. Working very quickly, if you are using the glue that we
mention, then twist the shell halves as completely as possible, try for 360ยบ or more
to make sure that the glue coats the entire inside lip of the shell. If the
shell is not completely glued it will create a weak spot in the shell and the
shell will not perform properly. Make a last round with the glue on the entire
outside lip of the shell. Watch the shell carefully to make sure that the air is
not still pushing the shell halves apart. If it is then you will have to hold
the shell closed or place it in a jig mentioned above. Strong tape placed top to bottom usually works
(careful the time fuse). Let the shell set for
at least a half hour watching that it is completely sealing. After dried remove
the tape before continuing with the rest of the building process.
PHOTO shell being glued shut
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NOTE: Pyrogen is a thick mixture of both Black Powder and Nitrocellulose
dissolved in Acetone. A very hot mix of pyrogen will ignite, without being
topped with granulated Black Powder, by the mere touch from the spark falling
off of a cigarette. (Did we mention not to smoke while shell building?)
NOTE: Black match is cotton string soaked and coated with Black Powder so
that it catches fire easily. It can be used as fuse, as cross-match that insures that the
time fuse will be lit or, it can be used to make
quickmatch. Very versatile stuff!
NOTE: Quickmatch is black match that is contained in a paper or water
resistant cover or sleeve. Placing the black match in this sleeve makes it burn
incredibly fast. Almost instantaneously burning from one end to the other no
matter how long it is! A delay fuse must be used with quickmatch, it cannot be
ignited directly without injury to the person with the lighter!
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After the shell has dried it is time to put the hook on top of the shell, if the
shell comes with one. If the shell has a hook coat the bottom of the hook well
with the Zylene glue and place it into the hole on the top of the shell,
twisting it several times to insure that there is a complete seal. Allow the
hook to dry for a few minutes.
Place the shell on its side in a way that it will not roll away, or off of the
table that you're working on. For the 4" shell that we are working with here you
will need at least a ??" length of quickmatch. Cut the quickmatch to length and lay it on
top of the shell with the end toward the time fuse having an extra 3-4" that
will be cut off later.
Tape the quickmatch to the side of the shell, and if there is a hook place the
quickmatch through the hook. Sometimes it is not an actual hook, but a plastic eyelet
that the quickmatch must be ran through before taping.
With a hook/eyelet or not, taping the shell this way insures that the shell will always
be placed in the mortar tube with the lift charge down.
PHOTO quickmatching the shell (With a HOOK/EYELET and without)
Cross-matching the outside of the shell is the next step. We do this in three
ways depending upon how much time we have on our hands. No matter which way is
used the entire point is to insure that good fresh powder core of the time fuse
is exposed to insure ignition. Whichever way you use remember the timing of the
fuse is very important, so use the same method every time that a shell is built
to insure a consistency of the shells.
The first way is the quickest way. Just poke a hole in the top center of the
time fuse with a pen or knife to expose the fresh powder. The end of the time fuse
is coated with a hot pyrogen and granulated Black Powder is quickly poured on
top before the pyrogen dries. The BP granules will set up in the pyrogen and
give it a greater surface area that will be exposed to the lift charge fire.
The second way! Using a razor blade cut the time fuse down 1/4 inch from the end
of the time fuse. Black match is then inserted into the cut up to the exposed
core of the time fuse. Close the cut with string or even tape to keep the powder
core from spilling out.
The last way is the industry standard way that both ends of the time fuse is
cross-matched for each and every shell that is built. This involves actually
using black match going through the side of the time fuse this gives the fire a
double chance to set the core of the time fuse on fire.
We have a nifty tool sold by Rich Wolter of Wolter Pyro Tools that does a great
job of punching the hole in the side of the time fuse. The black match is then
ran through this hole. This hole can also be made using an Awl, but the tool
above does a much cleaner, better, and faster job.
PHOTO -- PHOTO -- PHOTO (outside time fuse, hole matched--cut matched--pyrogen
sprinkled with BP matched)
Now it is time to connect the quickmatch and the cross-match with the lift
charge. Depending upon the size of the shell you can use ready made Dixie cup,
cone shape cups or make a cup of your own to hold the lift powder. For the 4"
shell here we used a Dixie cup. As long as the cup, ready made or self made, is
large enough to hold the lift charge powder and is not larger than the shell is
all that matters. It doesn't even matter how good it looks, as long as it works!
Take the quickmatch and strip off the paper cover/sleeve on the last 3-4" and
place it next to the cross-matched time fuse. Place the lift cup with the lift
charge in it over both and insure that both are in contact with the lift powder
and the ends of the quickmatch are not caught between the cup and the shell. You
will have a lip in the lift cup where the quickmatch goes into it.
Then tape, or hot melt glue the lift cup to the shell, being sure to cover the
area where the quickmatch enters the lift cup so that the lift powder will not
spill out.
PHOTO lift cup being glued/taped on with q-match area in view
The final step is to add a delay fuse to the quickmatch. The delay fuse is a
length of visco, cannon, or black match inserted into the quickmatch and THE
DELAY MUST BE AT LEAST 3 SECONDS to allow you to get away from the shell once
ignited! We connect the two with pyrogen, but strong tape will do a good job if
tightly placed on the fuses. Just insure that the visco fuse is inserted well
into the quickmatch and that the two fuses make contact. An IMPORTANT AND REQUIRED
STEP is a safety cover on the delay fuse. The safety cover must be a different
color than the quickmatch, and it must completely cover the delay fuse.
PHOTO delay fuse and safety cover on quickmatch
You now have a firework that must be either fired off the same day, or stored in
a BATFE approved Type 4 or better Low Explosive magazine. If a salute shell is
made it must be stored in a Type 1 or 2 High Explosive magazine.
PHOTO of shell being hung over a mortar by the quickmatch showing safety cap on the
fuse
All shells 6" and over must be fired electronically for safety, and we fire
almost all shells, of all sizes, electronically for this very reason. Think of
this!!!! If a 6" shell goes of on the ground, it will spread flaming balls 200'
in all directions. Do you want to be near it? If you've heard and 'felt' a 3"
salute in the air ... think of it going off on the ground, with you nearby?
Below is a photo of a shells quickmatch being modified with an electric match.
On the left shows the delay fuse with the safety cap removed. Second shows an electric match
laying next to the quickmatch where the delay fuse has been cut off. On the left
shows the electric match inserted well into the quickmatch and then they are tied together. When the
electric match is fired the quickmatch sets off the firework instantly, without any delay.
This is how firework shows can be timed to music.
Using a different type of stars you can ring the circumference of a shell, as
described above, to make a Saturn Shell. Below are more 4" shells for you to see
the inside construction. One has a heart design using red stars and the
other is a Saturn shell. The possibilities for designs on the insides of shells,
thus the design in the sky, are endless.
PHOTO guts of Heart shell & a Saturn shell side-by-side (Others too?)
