The Beautiful 4" Spider Web Shell

Making the Spider Web Shell – AFN Vol. 3

One of the most spectacular yet simple to make fireworks shells is the Spider Web. It is also one of the most inexpensive shells. Some companies call this shell the Octopus, but the effect is the same. This shell packs a dramatic punch when it bursts. Exploding with a bang, it instantly fills the sky with golden tentacles spreading radially in straight lines and in all directions from the center. The gold stripes are formed from the burning powder charcoal trail left behind as the stars are hurled at high speed. The pattern just hangs in the sky for many seconds before fading. A 4″ canister Spider Web shell, when made properly, looks like a 6″ chrysanthemum. Fire five of these in a salvo or flight and an awesome checkerboard spider web fills the sky! Here’s how I have refined the Spider Web to perform better than any others I have ever seen:

The Secret is the Star

Stars are cut 5/8″ or 3/4″ (large) square. The formula:

    Formula 1
Commerical Meal D 10.0 lbs
Potassium Nitrate 7.5
Air Float Charcoal 7.5
Sulfur 1.0
Dextrin 2.0

Formula 2
Potassium Nitrate 15.0 lbs.
Air Float Charcoal 9.0
Sulfur 2.0
Dextrin 2.0

While the formulae are given in pounds, smaller batches can be made by substituting grams, ounces, etc. for the lbs. or by multiplying or dividing all the quantities by the same number, keeping ratio relationships the same.

For example, Formula 1 can be weighed out in ounces with each quantity multiplied by two to make enough stars for 3 or 4 shells. Formula 1 is a very fast burning star because it is 50% commercial Meal D black powder. It will ignite 100% from the strongest flash bag. The stronger, the better!

Formula 2 needs to be ball milled for at least ten hours to be almost as fast, yet just as ignitable as Formula 1. Because it burns slightly slower than Formula 1 (after ball milling), those stars achieve a larger spread in the sky. Ball milling also serves another purpose. It reduces the amount of ash and shortens the charcoal glow time. Without ball milling, some of the sparks may glow all the way to the ground. With ball milling, the golden stripes are more uniform and more beautiful, fading in unison.

Formula 1 (less the Meal D) can also be ball milled to achieve uniformity and less ash. The Meal D is added after ball milling the rest of the chemicals. Very slight dampening with a volume mix of 80% water with 20% denatured alcohol is helpful during ball milling. By slight I mean just enough to settle the dust but the mass still feels dry and flows freely as a powder.

Commercial quantities can be ball milled in an electric cement mixer that has been modified. I did this by removing the blades and reinstalling the bolts to prevent leakage of powder out the bolt holes. I also removed the motor and replaced it with a totally enclosed (sealed) motor and thoroughly electrically grounded the machine. Ball milling of a mixer charge of 28lbs. of Spider Web mix, was done with a set of inexpensive Boche Balls! The mouth of the mixer was sealed with a sheet of heavy plastic cut in a circle larger than the opening of the mixer vessel. The plastic cover was held in place with bungie cords. After 10 hours, the powder was absolutely beautiful and the stars it made performed exquisitely.

If one tries to burn the star composition after mixing and ball milling, one will be disappointed. It appears to be smoldering and slow as if something were done wrong. This is normal. After the stars are made by thoroughly dampening with water, forming loaves in a frame, slicing, dicing, dusting and drying, the stars perform quite differently. Burn time for a 3/4″ star is less than 1 second. The star is very sensitive to low temperature incandescent heat ignition, yet is very stable and insensitive to friction or impact. This makes the star ideal for hard breaking flash bag bursts!

Once the stars are made, I use the following materials to assemble a 4″ Spider Web Shell:

Shell Materials:
  • Paper Can with end caps, 3-1/2″ dia. x 4″ long
  • 3 Chipboard discs, 1/8″ thick x 3-1/2″ dia.
  • 1/4″ Time Fuse, 3 seconds between cross match
  • Dime size Coin Wrapper for making Flash Bag.
  • Wooden Dowell, 5/8″ x 4″ for making Flash Bag.
  • Masking Tape.
  • Spool of 12 ply Cotton Twine or equal shell twine.
  • Enough good Flash Powder to fill a dime wrapper.
  • Igniter Cord\Black Match for cross matching time fuse.
  • White Glue and/or Hot Melt Glue and gun.
  • Homemade granulated black powder.
  • Wallpaper wheat paste.
  • Kraft Paper, 70 lb. and 20 or 30 lb. grades.
  • Quickmatch\fast fuse.
  • 2FA Black Powder for Lift, 2 oz.

Putting it All Together

Assembly is as follows, refer to Fig 1.

The shells can be made the traditional way of rolling a paper casing but my way (with paper cans) is easier to assemble and performs equally well.

Two of the chipboard end discs should have center holes to receive the 1/4" time delay fuse. With Elmer's white glue, I fastened a disc inside the loose end cap of the paper can (the can bottom end cap should already be glued in place). A weight is then placed on this disc and set aside to dry. Next, I slide the dowel down inside the dime size coin wrapper almost the full length of the wrapper. I then crimp the end of the wrapper over the end of the dowel to close off the dime wrapper and form a bottom. A short piece of masking tape is then placed over this crimped end to seal the bottom of the soon to be flash bag. Using a hot salute flash powder, I fill the flash bag 3/4 full. Next, the time delay fuse, cut to the correct length and cross matched with ignitor cord\black match, is inserted (with cross match) into the flash bag. The bag is gathered around the time fuse and tied with twine just above the cross match.

Being sure to center the flash bag among the stars, I next load the stars and flash bag into the paper can. The spaces between the stars can be filled in with pulverone or granulated homemade black powder. The pulverone filler is necessary with hand rolled casings but optional if using a paper can. This type of shell functions equally well without pulverone. The top edge of the flash bag where it is gathered around the time fuse must be kept even with the top edge of the paper can. Next, I smear a generous portion of white glue around the inside circumference of the paper can end cap that was previously set aside. Holding the time fuse centered, I lower the paper can end cap with chipboard disc (glued inside cap) onto the fuse and paper can. Once the end cap is seated onto the paper can and while applying hand pressure to keep the cap from springing back up, I apply masking tape around the circumference of the cap where it meets the can wall. The bottom end cap of the paper can is also taped and sealed.

I next gently pull up on the time delay fuse to assure that the top of the flash bag is against the inside disc. A generous portion of Elmer's glue is smeared on the outside of the top end cap and around the time fuse to seal against lift flame entry. I then assemble another chipboard disc with center hole over the fuse and down against the paper can end cap. This disc is taped down in four locations 90 degrees apart to hold it in place while the glue dries. The third solid chipboard disc is glued to the bottom of the shell in an identical manner. Next I glue a generous fillet of Elmers around the type delay fuse to complete the double seal against lift flame. The shell is now set aside for the glue to dry overnight.

The next step is spiking the shell with twine. Two parallel lines of twine are applied simultaneously to give a strong hard break and symmetrical pattern.

I start by looping the free end of the twine around the time fuse, holding the end down, as twine is fed out and lead down against the shell wall, crossing over the top of the free end. The spiking pattern follows the sketch in Fig. 2, and is tied off with a clove hitch knot around the entire circumference of the shell, after spiraling up the side.

The strength of the spiking will be greatly enhanced by running cotton twine through a wheat paste slurry and wiping off the excess as it is applied to the shell.

After spiking, the shell is ready for pasting. Kraft paper (70 lb. rating) is cut so the paper grain will lie parallel to the shell length. The width of the paper is cut so that it will cover the full length of the shell, and fold over to cover 2/3 the diameter of the shell at each end. The length of the paper should be 48 inches.

Each shell gets pasted with a sheet this size. A slurry of wheat paste is prepared and generously brushed on both sides of the paper. The paper must be thoroughly soaked. The paper is folded like a bellows and squeezed with the hands to make the paste penetrate the fibers of the paper and to soften the paper.

I then smooth out the paper on a formica table top and roll the shell tightly, centering the shell in the paper while working out any air bubbles. The paper that extends over the ends of the shell is torn in strips about an inch wide. The tear is made from the end of the paper to the end of the shell. Those strips are laid down over the end of the shell and smoothed tight against the spilling, working out air bubbles. On the fuse end, I keep all the strips on the same side of the fuse as I rotate the shell and laying down each strip. I make sure there is a good tight seal around the time delay fuse. When finished, the shell is set aside to dray and in the air stream of a fan or out in the sun.

The shell can be finished as any shell. The final cross match fuse hole is punched in the fuse and a piece of igniter cord is inserted. I have also split and primed the time fuse with nitrocellulose lacquer and black powder when out of ignitor cord. Some shell makers finish the shell with the time fuse up and a pass fire quickmatch connecting the top of the shell with the lift powder at the bottom. The quickmatch long fuse is introduced to the top of the shell where the time fuse and pass fire are connected. I prefer to invert the shell, putting the time delay fuse directly into the lift powder. However, I wouldn’t do this if I were using a spoolette time fuse. Spoolette time fused shells have to be fired fuse end up or the spoolette core will blow through on lift.

Finishing It

For final assembly, I roll the shell with a quickmatch long fuse, in 3 turns of 20 or 30 lb. dry kraft paper. The long fuse lays parallel to the shell. The paper should be wide enough to cover the length of the shell plus cover the full diameter of each end of the shell. The end of the quickmatch has the paper trimmed back 3/4″ to expose the black match. This end is bent over the end of the shell where the lift charge will be introduced.

Two ounces of FFA commercial black powder is poured into this end of the shell covering the bare end of the quickmatch and surrounding the time delay fuse. The paper, starting with the inside rolled layer, is laid down over the black powder. The final turn of paper is gathered and tied off. I then trim off any excess paper beyond the clove hitch knot. The final touch is to install a mopoline or safety cover on the end of the long fuse to be ignited. The long fuse is then folded and secured with a rubber band and labels placed on the shell.

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