2.5-Inch Paper Ball Shells

INTRODUCTION

This article is geared toward building professional-style ball shells with a symmetrical and spherical burst pattern. Use this article as a guide to create an incredible show with authentic 2.5" ball shells! The article covers the use of red stars, although any other stars can be used to your liking. AVOID chlorate-based stars, as those are incompatible with black powder!! For building pro-style spherical red shells, we are going to be using two primary components: BLACK POWDER and RED RUBBER STARS. Since this is a kit ready for loading and geared towards the art and techniques of shell-wrapping, we are hoping you have a bunch of black powder and red stars ready to load into shells. However, if you don't, here is an outline on how to get there, fast:

Convenient kits to make these components can be found here:

Black Powder (Ball Mill Method) or Black Powder (Red Gum Type)
Red Rubber Stars
Hot Star Prime

PREP YOUR WORKSPACE

In any fireworks building activity, take the time to make sure things are organized and well situated. Good organization not only makes for a safe workplace but also can eliminate stress in the process because you know where everything is! Plus, by investing a little time to prep the area, you end up saving time because you know where everything is, things are in reach, and you end up producing better quality fireworks. As you go through the process, make a point to clean up along the way. This isn't nagging - it's peace of mind and safety, and translates to better quality. Take your time - these are powerful and beautiful devices if made properly and you want them to work consistently, don't you?! So...Take the Time to get your workspace setup!

For making stars and BP, a pop-up tent set up just outside the garage or your backyard works well to avoid getting a build-up of solvent fumes or flammable dust everywhere. A good part about a little black powder dust - once it rains or you hose it down, it goes into the soil and helps make your plants grow a little better! Charcoal, sulfur, and potassium nitrate are good for the soil! (in small quantities).

PLANNING AND PREPPING STARS AND BLACK POWDER

To get an idea of how much star composition to make and how much black powder you'll need, consider the approximations below:

Stars: 45 grams (1.6 oz) per shell
Fine Bursting Black Powder: 30 grams (1.1 oz) per shell
Course Lifting Black Powder: 17 grams (0.6 oz) per shell

This is a kit with many shells, so here is a breakdown of larger quantities of shells to help with planning your black powder and star batches (based on above numbers):

# of Shells lbs of Stars lbs of burst BP lbs of lift BP
5 0.50 0.34 0.19
10 1.00 0.69 0.38
20 2.00 1.38 0.75
40 4.00 2.75 1.5

 

Screen slicing the stars used in these 2.5" ball shells will require a STURDY 4 MESH SCREEN.
Screening black powder (BP) to make lift will require the 4-mesh screen and a 10 MESH SCREEN.
Screening the finer BP granules to make burst will require a 20 MESH SCREEN.

A Few Tips For Making 2.5" Ball Shell Stars:

We are going to be using Ned Gorski's Red Rubber Stars article.

There are a few modifications to the stars made in the article to pay attention to:

  • Use a 4 MESH SCREEN to slice your stars, not a 3 mesh screen as described in the article
  • Use 1/8" thick shims in place of the 3/16" shims to obtain 1/4" cubic-like stars
  • More prime is needed due to the increase in surface area of smaller stars
    • Ned recommends 85 grams of each prime composition for every 225 grams of star composition using a 3-mesh screen. Make 100g of each prime for every 225 grams of star composition instead, to make sure all your stars get evenly and fully covered.

The 1/8" thick shims in combination with a straight dowel are used to roll the star composition into a uniform patty with perfect thickness for use with the 4 mesh screen. We used 1/8" x 1/2" aluminum bars as shims - a couple of these bars end up being less than a dollar combined. I use a 1/2" diameter aluminum dowel to roll out the composition. The bars and dowel end up being about $3 combined, which I buy from a local metal shop. They are strong and will last forever. The parchment paper can be used if waxed paper is found to be too flimsy.

Star making shims
1/8" shims and 1/2" dowel used for making stars

 

Unprimed red rubber stars
Red rubber stars, unprimed
Primed red rubber stars
Finished stars, primed

 

A Few Tips For Your Black Powder:

Homemade BP (either Red Gum or Ball Milled) will work. Ball milled or commercial BP is recommended for the burst charge since it has tougher grains and will stand up to the pressures involved with packing the shells together and the lift charge.

So, to make sure, here are the links to making you black powder:

Black Powder (Ball Mill Method) or Black Powder (Red Gum Type)

The fireworks screens required to separate the powder are here:

Screening lift powder will require a 4 MESH SCREEN and a 10 MESH SCREEN.
Screening your burst powder will require capturing BP grains between the 10 mesh screen and a 20 MESH SCREEN

Your BP for lift and burst should look like this:

Black powder burst and lift

Before even starting on this kit, you must have BP and primed stars ready for action! Once you do, and you have used the above table to estimate and confirm how much of each you will need, go ahead and proceed to the next steps, below!

SETTING UP THE WORKBENCH FOR SHELL ASSEMBLY

These preparatory steps will add consistency to your assembly process and save you time in the long run. Get organized. Put a fresh layer of kraft paper down on your workbench. Tape it down so it won't move. Lay out the necessary components and tools for shell assembly.

Tools & Supplies Needed:

  • Kraft Paper - heavy kraft for covering table, light kraft for transferring stars/powder
  • Tissue paper sheets
  • Scissors
  • Drill bit for time fuse: 1/4" diameter
  • Drill Press (preferred) or cordless drill (one of the two)
  • Retractable blade and/or box cutting blade
  • Wood block (for tapping shells together and something to cut on)
  • Narrow block of MDF - 14" or longer (for tape cutting)
  • Masking tape
  • Strapping tape (for taping the equators of the shells)
  • Sponge and small Tupperware or shallow glass container (for wetting gum tape)
  • Ruler / tape measure
  • Sharpie
  • Thin cotton string
  • Stainless steel tweezers (for star placement)
  • 1 oz plastic cups
  • 3 oz paper (or plastic) cups
  • Hot glue gun and glue sticks
  • FROM THE KIT:
    • Paper hemispheres (aka: "hemis")
    • Time fuse (the fat fuse that looks like a coiled up candy cane)

Making Your Tape Board:

First, make a tape board using a slat of MDF, like the one shown below:

Tape board
Tape Board, with top layer of strapping tape, and two layers masking tape below

Measure a straight line of 13.5" length, and mark the ends using a Sharpie. This line will be used to speed up the strapping tape cutting. For each shell, a little less than 3/8" wide strip of strapping tape will work well for wrapping a shell. One strip of 1" wide strapping tape will give you 3 pieces to secure 3 shells, explained further down in this article. You can mark down as many 13.5" lengths on the MDF board as you want, depending on how many shells you plan to make. Or you can use the same one and just keep putting a new strip on it - whatever works for you. Once the strapping tape piece is pressed to the board and cut to length, cut the tape parallel to the fibers, along the length. You will have perfect pre-cut strapping tape lengths needed for shell making.

Underneath the 13.5" line section, lay down some strips of masking tape in the same direction, and rub them firmly into the smooth MDF surface. We want to make tape strips of 1/2" wide, 1-1/2" long. A LOT of them. Using a sharp blade, cut the masking tape into ~ 1/2" wide strips. Here, we use 1" wide tape, so we only need a centered, lengthwise-cut (if needed, use a straight edge like a ruler as a guide). Then, slice the masking tape lengths into ~ 1.5" lengths (approximately, doesn't have to be exact). The picture below shows a convenient layout for making about 3 shells, with the cut marks depicted in dotted lines. If you want to get fancy, use the blade tip and lift each corner of tape up a little to make it easy to peel the pieces off the board.

Use the board over and over again to lay out as much tape as you need, to make as many shells as you need. If it gets all cut up over the months, just flip it over and start over again!

Tape board
Tape Board, with top layer of strapping tape, and two layers masking tape below Tape board with suggested cutting line traces. Red lines: masking tape / Blue lines: strapping tape. (One strip of strapping tape already removed)

PREPPING THE HEMIS

Tools & Supplies Needed:

  • Drill bit for time fuse: 1/4" diameter
  • Drill Press (preferred) or cordless drill (one of the two)
  • Masking tape
  • Sharpie

Figure out how many shells you want to make. Take double that amount of hemispheres and match them up so each pair fits well together. Some of the strawboard hemispheres may be slightly oval. You may have to mix and match, and occasionally massage them, to get them circular and matched in pairs. With each pair of hemispheres, rotate them to find the best match. Mark each matched pair by pressing the equators together and putting a Sharpie mark across the equator to mark a pair. Optionally, you can keep the pairs together with a little piece of masking tape for organization.

Example of matched shell hemispheres
Example of matched hemispheres. Sharpie mark for alignment.

Next, drill holes in every 1 of 2 of each of the hemi pairs. Drill through the top-center of each hemi. Use a 1/4" diameter bit and a drill press to make this efficient.

Holes drilled in hemi pairs
1/4" holes drilled into one side of matched hemi pairs.

CUTTING/INSTALLING THE TIME FUSE

Tools & Supplies Needed:

  • Retractable blade and/or box cutting blade
  • Wood block
  • Ruler / tape measure
  • Sharpie
  • Wooden coffee stirrers

Cutting the Time Fuse

When we tested the burn rate of this time fuse (the fat fuse that looks like a coiled up candy cane), a 5" length burned in about 12.7 seconds end-to-end. That's about 2.5 seconds per inch. That's also about the right timing for the delay of these shells, so we'll need 1" of solid time fuse going into the shell. That catch is, you will need extra fuse length for proper ignition, as we are going to be slicing the fuse sticking out of each shell down its length to catch the fire from the lift charge. So we chose 1-3/4" lengths of fuse for each shell.

Take your time fuse, and unwind one end of it, bending it to be kind of straight. Using a ruler or tape measure on the work table, lay out the time fuse and Sharpie mark it every 1-3/4". Cut off the last mark you make (depends on how many shells you have). Now cut the fuse along these lengths using a sharp, sturdy blade (a wood block comes in handy here as something to cut on). This is THICK and HARD fuse, it will take a little while to cut through, so rotate the fuse while pressing the blade towards the wood block to let the blade work its way into the center and through. DO NOT USE SCISSORS - THEY WON'T WORK WELL AND THEY MAY SPARK AND IGNITE THE FUSE.

Cutting time fuse
Cut time fuse pieces at 1-3/4" lengths

Installing the Time Fuse

Take your pieces of time fuse and insert them into the fuse holes you made with the drill with hemi equator face down on the table. Stick the fuse straight down until it hits the table. About 3/4" of fuse should be sticking out the top of the hemi.

Installing time fuse in hemis

Apply a little hot glue evenly around the exterior of the hemi-fuse interface, making sure to cover any gaps along this joint. Then, flip the hemis over, onto 1oz plastic cups, to reveal placement of fuse. You may need to readjust the fuses to be centered in the hemispheres before the hot glue sets in place.

Fused hemis on small plastic cups
Placing fused hemis on those 1-oz cups props them up in place

Let the shells cool for a little while to lock in the hot glue. After the hot glue has hardened, come back and fill in the inside of the hemis around where the fuse comes in with some more hot glue. Again, make sure to apply an EVEN COATING INSIDE - NO GAPS! This is to make sure the pressure and fire from the lift charge won't pierce through any holes, which would cause the shell to explode in the mortar! Continue on other hemis until your batch of shells is done.

Fuses centered and glued in place
Fuses centered, glued in place with hot glue

Final thing to do on the inside time fuse end is to cut a little slit in it with your blade. On each of the ends of the time fuse (inside the hemisphere), slice it ~1/4-inch down, and rock the knife back and forth to open up the slit like a wedge opening. This will ensure good fire transfer from the time fuse to the burst charge inside.

Slicing inner time fuse for reliable ignition
Slice and wedge open ends of time fuse for reliable shell ignition

PREP THE WORKSPACE FOR FILLING AND BUILDING THE SHELLS

Tools & Supplies Needed:

    • Kraft Paper - heavy kraft for covering table, light kraft for transferring stars/powder
    • Tissue paper sheets
    • Scissors
    • Retractable blade and/or box cutting blade
    • Wood block (for tapping shells together and something to cut on)
    • MDF tape block (described previously in this article)
    • Masking tape
    • Strapping tape (for taping the equators of the shells)
    • Ruler / tape measure
    • Sharpie
    • Stainless steel tweezers (for star placement)
    • 1 oz plastic cups
    • 3 oz paper or plastic cups

3oz. cups

    • Small food scale for weighing things out (Amazon item, ~$12)
      • Ie: Scale

Digital scale

MAKE TISSUE PAPER SACKS

  • Take a sheet of tissue paper, and cut it up into 4" squares.
  • Use two of your 1oz souffle cups, and press each square between them to form little paper sacks
  • You will need 2 sacks for every ball
Tissue paper squares
Cut 4" squares of tissue paper
Primed red rubber stars
Use 1oz cups to form paper squares
Tissue paper cups
Press cups together to form paper cups
Tissue paper cups
Tissue paper cups ready for burst charge filling

FILLING AND BUILDING THE SHELLS

For each pair of hemis, we will now fill them with stars and burst! For these shells, I used a scale and weighed out the stars and burst in grams. If you want to eyeball it, fill each 1-oz cup about 2/3 full by volume. Depending on the stars you use, your weights might be a little different. I used a commercial BP (FFFg) for burst charge, which is dense compared to other homemade powders. Based on your burst and stars, you may need to tune your weights until you find a combination that works best for loading these shells. The idea is to get an amount of stars and burst that will completely fill each hemi with material, so when you bring them together, everything packs together nicely without a bunch of loose material shaking around inside.

Here's the basic layout for each RED shell - use this as a starting point, and adjust based on your components:

Hemi side with fuse:

  • Stars for fuse-side of hemi: 21g
  • BP burst charge per hemi: 14g
  • Tissue paper sack

Hemi side without fuse:

  • Stars for fuse-side of hemi: 23g
  • BP burst charge per hemi: 15g
  • Tissue paper sack

To keep things organized, I found the 1-oz souffle cups come in handy here.

Stars and burst weighed out
Stars and burst weighed out for each pair of hemis

FILLING TIME-FUSED HEMISPHERE

  • Stars for fuse-side of hemi: 21g
  • BP burst charge per hemi: 14g
  • Tissue paper sack

Start filling up the hemi with the time fuse in it. Pour in most (70~80%) of the stars, and tap the hemi to let them settle in. Take your tweezers and stack the pile of stars at the bottom up along the inside of the hemi. The idea here is to play Tetris with the stars and have them hug the walls of the inside of the hemis. Use a pair of tweezers to stack the stars. Tweezers make this process FAST!

Stars arranged in shell half
Stars arranged inside hemi, around time fuse. Use tweezers!

Stack the stars so you have just one layer of stars hugging the inside of the hemi. Just get most of the stars close to the equator of the hemi - there will be a few extra stars needed, but it gets really hard to stack them without the stars at the top falling into the center. Don't worry - leave the upper edge without stars.

Next, pour your BP burst charge into one of the little tissue paper sacks you made and wrap it up into a little ball.

Burst charge sack
Burst charge sack being made for filling a hemi

There is a TRICK to get the burst charge sack over the time fuse - and it is EASY.

Bundled up burst charge
Bundle up fuse-side burst charge
Burst centered over tip of time fuse
Center over tip of time fuse
Burst pressed over time fuse
Press burst sack DOWN
over the tip of the time fuse
Burst sack filling hemi
Burst sack will fill the
hemi and keep stars in place
Time fused pushed through burst sack
Time fused pushed up through charge
Remaining stars poured into shell
Remaining stars poured
between hemi and sack

Make sure you get those remaining stars tightly packed along the equator with your tweezers.

FILLING THE NO-FUSE HEMISPHERE

  • Stars for fuse-side of hemi: 23g
  • BP burst charge per hemi: 15g
  • Tissue paper sack

The process for the NO-FUSE hemi is essentially the same as the TIME-FUSED hemi.

OK, just like the other hemi, pour in most of the stars and arrange them with the tweezers to pack tightly against each other along the inside wall, like this:

Unfused shell hemi filled with stars
Layer of stars stacked/arranged in NO FUSE side of hemi

Just like the other hemi, just get most of the stars close to the equator. Pour your BP burst charge into another one of the little tissue paper sacks you made and wrap it up into a little ball.

Burst charge sack
Burst charge sack being made for filling a hemi

Take the burst charge sack and drop it into the hemi with your neatly-stacked stars in them. The burst sack will keep the stars underneath in place, and the tissue paper will stick up, like this:

Last stars inserted between hemi wall and tissue paper

Now, the remaining stars can be inserted between the inner wall of the hemi and the tissue paper sack without the stars falling into the center! Fill the remaining stars up to the equator of the hemi using a pair of tweezers.

Stars tightly packed around equator of hemi
Tightly packing stars around equator of hemi
Tissue paper folded over burst charge
Fold edges of tissue paper over burst charge

Once you get both hemis filled with stars and burst bags, you should end up with two halves of a shell, ready to be mated together, like this:

Hemispheres ready for mating into a complete shell
Hemispheres ready for mating into a complete shell

ASSEMBLING THE SHELL TOGETHER

Carefully remove each hemi from its holding cup and place a hemi in either hand. Match the edges up as best as possible, and then quickly and confidently hinge them together from adjoining edges to form a complete ball. The video below shows the process of bringing the shell together, packing in the contents, and tapping it in place:


Two hemis brought together, packed together with help of wood block

Pointers for bringing shells together:
- Use your Sharpie markings as a guide for the best matching edges.
- Keep the hemis together firmly as you tap things in place, as there will be stars and tissue paper visible along the equator.
- Some burst powder and a few stars may fall out - not a big deal. Just bring the shell together. If you see a place to put a star or two back in, go ahead.
- Gently tap the exterior of the hemis while pressing them together tightly to allow the stars and powder to relax and pack tightly into the hemispheres.
- Keep rotating the pieces, holding them together, with some pressure, and tapping on the exterior of the hemis to eventually close up the shell. - A little rotation along the equator can help encourage a tighter compaction.

TAPING SHELLS TOGETHER

With the pre-trimmed and edge-peeled masking tape pieces ready on your tape board, secure the packed shells by taping the hemis to each other using masking tape pieces:

Taping shell halves together

    • Here's a good way to really get the hemi edges close:
      • Stick the bottom half of a tape piece to one hemi
      • Stretch the other half of tape up along other hemi
      • Stick it to the other hemi and press down firmly to clamp together
    • Repeat this tape pattern in a triangular pattern.
Holding shell for taping
  • Come back around and use the same process in between the triangular tape pattern, ultimately forming a six-sided tape secure.

Shell with six pieces of tape

With the two hemis now temporarily brought together by masking tape, take a 13.5-inch long piece of thin strapping tape (1/4~3/8-inch wide) from your tape board and wrap it along the equator of the sphere. Tightly. The tape should just barely overlap itself after two layers have been wrapped.

Strapping tape applied to equator of shell
Strapping tape being tightly applied around equator of shell

Protecting the time Fuse:

  • Wrap a small piece of masking tape all the way around the piece of time fuse sticking out of the hot glue - about two layers of tape is sufficient.
  • Mark the tape with a line along the fuse length using Sharpie - this will be used as a guide for later pasting the shell with the gummed paper tape.
  • Now is THE TIME to make a marking of the shell effect you built into each shell to keep track of the shells. Make this mark on the tape as well, since you will be covering up the ball with thick paper.
Time fuse protected with tape Masking Tape Masking tape lined Line Shells labeled with effect Label Effect!

SHELL PASTING INTRODUCTION

In this shell-pasting procedure, we are going to be using Ned Gorski's hybrid shell pasting technique, with a few modifications to account for the slightly smaller shells we are using (Ned makes 3-inch shells, we are making 2.5-inch shells).

Click below:

https://www.skylighter.com/blogs/how-to-make-fireworks/3-Inch-Hybrid-Ball-Shells

Then shoot down to the two sections titled:
"Determining the orientation of shell axes before applying gummed tape"
"Applying layers of gummed tape to shell"

Go over the process and videos he describes about building up the shell paper thickness.

Go over this in detail - really get a good understanding of how to keep track of the gummed paper tape layers being applied. It's a little complicated at first glance, but after making a few shells becomes second nature, like riding a bike. This process is essential to understand as it allows for a uniform build-up of glue and paper to make a strong casing. Key for symmetrical breaks! And critical to understand this process as we are going to be using it!

...Interlude for 20 minutes while you explore the link/watch the videos...
https://www.skylighter.com/blogs/how-to-make-fireworks/3-Inch-Hybrid-Ball-Shells

Now that you have taken in this method, here is how we are going to apply it to our 2.5-inch Shell Kit:

SETTING UP THE WORKBENCH FOR SHELL PASTING

For wrapping the paper shells, clear off your workbench and bring out the following tools and supplies:

Tools & Supplies Needed:

    • Gummed paper tape rolls (from the KIT)
    • Your freshly-made and taped-together shells!
    • A couple flat, soft sponges - cut up to fit in a Tupperware container.
    • Small Tupperware or glass container that holds the sponges. Choose one that is shallow so when the sponges inflate with water, the edges of the container are a little below that of the top surface of the wet sponges, like this:

Disposable tupperware sponge holder

  • A bottle of water
  • Two hand towels
  • Aluminum foil
  • Masking Tape
  • Sharpie

Here is a basic setup before you start wrapping your shells:

Shell pasting workbench
Shell Pasting Setup on Workbench

Lay out the aluminum foil, put a hand towel down over it, then pour water on it to make it sopping wet. The foil keeps the water from getting the table wet.

The other hand towel is for drying off your hands during the shell-pasting process. The glue from the gummed paper tape roll gets sticky, so these two towels help to keep your hands from sticking to everything you touch.

Most importantly...get comfortable! The wrapping process is going to take some time, especially if you have a lot of ball shells to wrap! Pull up your favorite chair, turn on some music, and get ready to wrap your balls in lots of paper!

PASTING THE SHELLS

There will be 3 complete sets of paper layers wrapped around each shell to create the final casing. Each of these sets contains, on average, 6 gummed paper tape layers. This amounts to an average of 18 layers of paper pasted around each shell - A LOT. This is what is needed to create a spherical, symmetrical burst pattern with black powder and stars.

Unwrap your gummed paper tape roll. There is a shiny side, and a dull-paper side. The shiny side has an adhesive on it that is activated by water. This is what we use the water-soaked sponge and tub for:

Shell pasting workbench
Wetting the gummed paper tape

Here is a breakdown of how each layer is made:

Note: C-bands (Circumferential bands) go around the circumference of the shell once; S-bands (Side bands) go along the sides of the shell. This is just like Ned's shell-pasting method, and spelled out in detail, below:

Layer 1:

X-axis:
3 x C-bands
8 x S-bands
Y-axis:
3 x C-bands
8 x S-bands
Z-axis:
3 x C-bands
8 x S-bands

X + Y + Z: Total bands: [3 + 8] + [3 + 8] + [3 + 8] = 33 tape strips on the first layer

Layer 2:

X-axis:
4 x C-bands
8 x S-bands
Y-axis:
4 x C-bands
8 x S-bands
Z-axis:
4 x C-bands
8 x S-bands

X + Y + Z: Total bands: 3 x [4 + 8] = 36 tape strips on second layer

Layer 3:

Same as Layer 2 (36 tape strips with 4 x C bands and 8 x S bands per axis)

Looks confusing, right? It's actually not once you do it a few times!

3 C-Bands on Layer 1
3 C-Bands on Layer 1
8 S-bands going around C-bands
8 S-bands going around C-bands
Criss-cross tape pattern
Layers 2 and Layer 3: 4 C-Bands + 8 S-bands on all axes. See the criss-crossing C-Band tapes?

That's a lot of tape strips, and a lot of wrapping. This has to be done ON EVERY SHELL. We've tried measuring and pre-cutting the lengths, but this quickly gets complicated and increases prep time. The best way to cut each strip is to tear the wetted gummed tape as you wrap, just like Ned did in the videos.

For shell burnishing (pressing the sticky paper together to remove air underneath the layers and compact everything), simply squeezing the ball shells firmly in your hand worked well, since these are smaller shells. Below, a shell before and after burnishing:

Taped shell before burnishing
Shell BEFORE hand-burnishing
Shell after burnishing
Shell AFTER hand-burnishing

Let each layer dry a little bit before applying another layer. If you have this setup outside on a warm, dry day, and you are making a bunch of shells, systematically apply the first layer to each shell. By the time you come around and are ready to apply a second layer to the first shell you wrapped with "Layer 1", it should be dry enough to do so.

You may find your hands getting tired after wrapping the first layer around the shells. TAKE A BREAK. Let the shells dry for a while, either for a couple hours, or a few minutes in the sun. This helps moisture escape the shell casing before the next dampened layer is applied, and ensures the moisture will not make its way inside the shell. Plus, you won't end up at the doctor's office for carpal tunnel syndrome or tendonitis from overactive squeezing!

Once the third and final layer of gummed paper tape has been applied to all shells, check them in the mortars for sizing. Below, a picture of finished shells wrapped with 3 layers of paper (each layer 3 axes), and an unwrapped shell for size comparison:

Comparison of wrapped and unwrapped shells
6 Red Shells with all 3 layers of paper tape, with an unwrapped shell in center for comparison.

Make sure the shells fit snugly the mortar tubes!!! Do a check on a few of these shells - they should fit like shown on the picture below:

Shell with a single layer of tape loosely fitting in the gun
Just 1 Layer of gummed paper - too loose
A shell with 3 layers of tape fiting snugly in the gun
3 Layers of gummed paper - good fit

Let the shells dry overnight. They will turn almost rock-hard on the outside - perfect for good burst performance and standing up to the pressures of the lift charge in the mortars. If the shells are still drying, they tend to feel cool to the touch. This is from water evaporating from the paper tape layer. Wait until they are DRY and HARD. While waiting, prepare the mortars and shell lift bags and leaders, below!!

GLUING THE MORTARS

Use hot glue to secure the mortar tubes to the mortar bases.

For each mortar, using a standard-size hot glue stick (diameter of 0.45-inches), you'll need:

- 2-inches of hot glue stick for initial tube fitting
- 4-inches of hot glue stick for bottom-filling

For the tube fitting, fill the inside rim of a mortar base with a half-stick of hot glue (2-inch length, 0.45-inch diam sticks). Immediately press-fit a mortar tube into this base, allowing the tube to push the glue around its bottom edge. Repeat for the other 9 mortars.

Mortar base filled with glue
Fill inside rim of base with hot glue, ~2-inches of glue stick
Gluing mortar tube in base
Press tube firmly in, squeezing glue around tube end
Top view of glued mortar tube
Top view of glue pressed inside base from inserting tube

Then, if you have a "hot" setting on your glue gun, crank it up. Our glue gun switched from 60W to 100W, which worked well. On high, squeeze a full 4-inch stick of glue directly down the center of the tube, letting the glue pile up and flow over the bottom of the mortar base. The idea is to get the glue to flow out and bind to the edges of the hot glue that was pushed inside the mortar base when the mortars were squeezed in there. Let these mortars cool for a while to lock in the base.

Mortar tube bottom filled with hot glue
Fill remaining base with 4-inches of hot glue

LIFT AND LEADERS

Now is a good time to make the lift bags and leaders that will be used to fire off the shells.

Tools & Supplies Needed:

  • Roll of White QUICK Hobby Fuse (from Kit)
  • Roll of Green Fuse (from Kit)
  • Black powder (LIFT grade)
  • Thin plastic snack baggies
  • Masking tape
  • Utility knife
  • Scissors
  • Tape measure (for cutting fuse to length)
  • Wood block
  • 3-oz paper cups

For each shell, you will need about 12g ~ 20g of lift powder, depending on how powerful your lift is. For example, if using lift made from the Red Gum BP method, you may need more lift than if you use ball-milled lift or commercial FFg or similar.

Weigh out your lift (I used 18g) and add it to a plastic snack baggie. Collect it in the corner.

Weighing lift

For each lift baggie, measure out 20 inches of white quick fuse from the Kit. Cut it using the utility knife on a wood block. This fuse burns VERY FAST! It will serve as your "leader" to activate the lift of the shells when you fire things off.

After cutting 20 inches of white fuse, fold the last inch of it in on itself, and secure this bend with some masking tape, as shown below:

White quick fuse
White quick fuse, 20-inch length
End of quick fuse taped
End of fuse bend and taped together

Stick the bent end of the fuse into your lift powder in the baggie, and wrap it up on the corner of the baggie like shown below. Secure the wrap with tape, and cut off the excess baggie with scissors.

Fusing bag of lift

Fold the baggie up against the fuse, and press it down inside a 3-oz paper cup. This cup will be your lift cup for each ball shell you've made.

Making lift cup

Make as many of these as the shells you've made. This will let you use the time productively to let the shells finish up drying!

SPLICING THE TIME FUSES ON THE SHELLS

Make sure the shells are fully dry before going forward - they should be hard to the touch when you tap on them with your finger nails.

Tools & Supplies Needed:

  • Your dried ball shells
  • White QUICK Hobby Fuse (from Kit)
  • Thin cotton string
  • Utility knife
  • Scissors
  • Wood block
  • Sharpie marker

Remember you labeled the shells on the fuse? Now is the time to write the shell effect on the ball shell. Write it down with a marker away from the time fuse, and remove the masking tape around the time fuse. Some of the string might unravel - doesn't matter.

Labeled shells
Label shells
Masking tape removed from time fuse
Remove Masking Tape around time fuse

Being very careful, cut the time fuse with a utility knife down the center across the length, to splice it open as shown below.

Safely cutting time fuse Keep hands clear of blade Splitting time fuse Rock back ‘n forth Outter time fuse split Stop above hot glue joint

Taking some quick fuse and a wood block to cut on, cut off 1 inch of fuse and carefully splice it lengthwise to open the insides up, like this:

Cutting quick fuse
Cut 1-inch of quick fuse
Splicing quick fuse
Splice quick fuse piece

With this little piece of sliced open quick fuse, we are going to push it into the spliced time fuse to create a cross-matched time fuse. This makes the time fuse on the shell SURE to ignite when the lift charge goes off, as shown below:

Spliced time fuse Spliced time fuse Pushing quick fuse into time fuse Push quick fuse in Cross-matched time fuse Cross-matched time fuse

Next, tie a piece of cotton string over the top of the cross-matched time fuse to secure the fuses in place. Snip off the excess string with your scissors.

Tying cotton string around cross-match

Do this for all the shells.

YOU NOW HAVE LIVE PRODUCT READY TO BE MADE INTO REAL FIREWORKS!

ASSEMBLING THE COMPLETE SHELLS

Tools & Supplies Needed:

  • Cross-fused ball shells (previously made)
  • Lift Cup and Leader (previously made)
  • Masking tape pieces (ie: from tape board)
  • Hot glue gun

Finally, this is where we mate the shells with their lift cups.

At a safe distance away from the live shells and lift cups, plug in your glue gun and start heating up the glue. Reload a glue stick if necessary, and get ready to apply more hot glue soon.

Place each shell over the lift cup, with the spliced time fuse over the lift bag in the cup. Press it down, and tape the fuse in place as shown below with masking tape, shown below:

Attaching lift cup to shell
Cross-matched shell over lift cup
Taping lift cup on shell
Tape in place

Next, place a strip of masking tape along the quick fuse (leader) and attach it to the ball shell. Unplug the hot glue gun, and add a couple dollops of glue above and below this tape piece. Place the assembly on the table and let it sit to cure the glue in place for a minute. Repeat this step for all the rest of the shells you are building. Plug the glue gun back in and warm up the glue for the next steps.

When the two dollops of hot glue fully cool and cure, you should be able to gently lift the white fuse leader and the whole shell and cup will be lifted using this fuse. If the glue is still mushy, it will not hold. WAIT UNTIL THE GLUE IS FULLY COOLED AND CURED before handling the shells. The shells, with their lift cups, are heavy for their size. They are dense. They each will weigh about a quarter-pound.

Masking taping leader onto shell
Masking tape across leader on shell
Hot gluing leader in place
Two dollops of hot glue

Almost ready!!!

OK, with the hot glue gun pre-heated again, unplug it and place 4 dollops of glue around each shell, where the shells and the lip of the lift cups meet. Place each assembly on the table and let the hot glue cure hard. Continue the process on the rest of the shells you have.

In the below picture, I went ahead and made a cut-away view port in one of the lift cups, so the inside workings of the shell could be seen. Notice how the cross-matched time fuse rests on top of the lift bag - ready to receive the flash of fire from the lift charge.

Completed fireworks shell
Completed shell and lift cup assembly
Lift cup cut-away
Cut-away view of the shell and lift cup

(No need to cut the window in the lift cup! This was just for instructional purposes to show the insides!)

TEST-FITTING THE SHELLS IN THE MORTARS

Tools & Supplies Needed:

  • Complete shells
  • Hot-glued mortars

Test fitting shell fit in mortar

Make sure your shells fit snuggly enough to fill the mortar tube, but are loose enough to slide down the tube with gravity. The clearance should be enough to let the shells slide into the mortars snuggly, to provide enough compression for the lift charge to build up pressure and fire each shell out of the mortar.

From this point forward - DON'T LOOK DOWN THE BARREL! THIS IS A LOADED CANNON!

SINGLE-FIRE SHELL SHOT

The white fuse that comes with this kit burns incredibly FAST! With short lengths of about a foot or two, the fire transfer is almost instantaneous. This is why there is green fuse in the kit - to give you time to run away before it reaches the white quick fuse.

Setting up a single shell to fire is simple. Cut a length of green fuse off that you are comfortable with and tape it to the end of the white fuse leader, using masking tape to secure the two fuses together, shown below:

Cutting visco fuse
Cut length of green fuse for delay
Mating visco fuse and quick fuse
Mate with white fuse leader
Taping fuses together
Tape fuses together using masking tape

CHAINING FUSE FOR AUTOMATIC FIRE

Splicing White Fuse for Reliable Fire Transfer

Once you have an idea of how you want to set off your shells, you can play around with the time fuse lengths and whether or not you want multiple shells to fire at the same time. If you want to set off a whole bunch-a-shells at the same time, we can take advantage of the incredibly fast burn speed of the white quick fuse! Remember, the white fuse that comes with this kit burns incredibly FAST! With short lengths of about a foot or two, the fire transfer is almost instantaneous. This is why there is green fuse in the kit, to give you time to run away before everything goes "thump-THUMP-PHOOMP"!

Depending on whether you are splicing a fuse leader to a fuse end, or two fuse leaders across each other, the process is very similar.

Fuse splicing tools
Components for splicing and joining fuse together

Splicing two fuse lengths running across or parallel to each other can be done as shown below:

Exposed fuse powder Expose fuse powders Mating spliced fuses Mate exposed fuses Taping spliced fuses Tape splice in place

Splicing the end of a fuse to a running fuse length can be done in a similar fashion, shown below:

Joining sliced quick fuse
Slice mating end of
quick fuse and joining edge
Mating quick fuse with tape
Mate exposed ends together - tape in placer

Here's 5 mortars chained together to fire off 5 shells at a time!

Five mortars chained together

Once you have all your mortars fused up and the leaders out and exposed, the only limit on how the shells go off is your imagination! NOW, GO LIGHT OFF THE SHELLS TO YOUR HEART'S DESIRE!!


Make Your Very Own 2.5" Shells
Just Like in This Project & Save 15%
Red fireworks shell bursts

(Sale starts 9/28/20 and ends at midnight 9/29/20)

Simply order a 2.5-inch Paper Ball Shell Kit during the promotional period listed above and the sale will be automatically applied:

2.5-inch Paper Ball Shell Kit - Makes 40, 2.5-Inch shells! Kit comes complete with 10-cardboard mortars and 10-plastic bases!

Purchase your 2.5-Inch Paper Shell Kit (KT7310) before midnight 9/29/20, and Save 15%-off the already discounted kit price!

Here's what you need to do:

2.5-inch Paper Ball Shell Kit - Makes 40, 2.5-Inch shells! 

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