Tiger Willow Shells in 2-1/2 Days, Day 2
IntroductionThis is a continuation of a series of articles that details the production of good, traditional, paper ball shells in a minimum timeframe, possibly at a three-day fireworks club event. I'm exploring the possibility of arriving at the meet with only a few chemicals, some other materials, some tools and equipment, but with no completed pyrotechnic compositions, and then producing these shells from scratch.
The original series of articles ran in 2007 in the Pyrotechnics Guild International's Bulletins #152-155, and this is a somewhat revised and expanded re-issue of that series.
RECAPYou may want to review the project "How to Make Charcoal" which detailed the charcoal options for this project. It included the production of homemade charcoal to be used in the various components of the shells. The charcoal-making step of the process would occur at home prior to travelling to the pyro get-together.
In "How to Use a Ball Mill Safely and Effectively", ball milling materials, skills and techniques were addressed.
In Part 1, "Tiger Willow Shells in 2-1/2 Days, Day 1", production of the black powder (BP) shell burst granules, black match, shell lift powder, and charcoal tailed stars were begun. Options for star rollers, drying chambers, hydraulic presses, star plates, and homemade shell casings were also discussed.
Goals for Today - SaturdayToday I want to check on how dry the items in the drying chamber are. I also want to granulate the BP pucks, prime the stars and finish drying them, make the spolette time fuses, assemble the shells and paste them in so that they can dry overnight.
8:00 - 8:15 am, Like Christmas MorningI woke up this morning wondering how everything in the dryer was doing. I opened it up, took two stars out of the top screen, and tapped them together. I've learned that when they are pretty dry they produce a crisp, clacking sound like two stones being knocked together. The stars are doing just that.
I then took a couple of the stars out to a safe place and lit them one at a time with the propane torch, tossing them into the air when lit. They both ignited well and burned with nice spark trails, burning out just after hitting the ground. This is just how I want this star to burn.
Back in the drying chamber, under the star screens, I unearthed the screen with the BP pucks on it. I stacked the pucks up and weighed them. Yesterday, I started with 20 oz. of mill dust and added 2 oz. of water, so when the pucks are totally dry they ought to weigh 20 oz. again. They now weigh 20.2 oz, so they have just a bit to go. When the pucks are completely dry, they "clink" when they are tapped together, sounding like pieces of pottery or china. This morning they have a slightly duller sound.
I cut a 6" piece of the black match off of the match frame and took it out into the field to light it. It was nice and stiff and it burned well and consistently.
And, from one of the bottom frames, I removed a very small handful of the burst granules. Putting them on a rock out in the field, I inserted a 6" piece of the blackmatch and lit it. Great. A quick poof and the puffed rice cores disappeared in the flame. Good and dry.
Ah, life is good. Warning: I have a buddy who wanted to demonstrate how his BP rough powder burned. He made a pile of it and lit it with the torch. The whole backside of his arm got badly burned. Always test burn compositions and devices by installing a piece of fuse so that you can retreat before it all ignites.
8:15 - 9:00 am, Crush BP PucksNow I want to crush the black powder pucks and screen the granules into usable sizes. First, I put a puck in a little plastic baggie. Then I put the baggie on top of my 6x6 pounding post and whack it with a metal-headed meat-tenderizing hammer until the puck is busted into about 2FA (about 1/4 inch) size granules.
I do this with all the pucks, one at a time, and dump the BP into a 4 mesh sorting screen.
Corned BP in a 4-Mesh (1/4") Screen
I sift all the granules out that will pass through that screen, and re-crush the granules that won't pass through, until all the BP has passed through that screen and onto a sheet of kraft paper.
4-Mesh Black Powder Screenings
Then I pass that pile through an 8-mesh screen. The granules that won't pass the 8-mesh, but have passed through the 4-mesh are dumped onto a paper plate, and are the 2FA lift powder, which will propel the finished shells into the air. (See black powder size charts.)
I then pass the remainder of the powder through a 12-mesh screen, and the powder that has passed through the 8-mesh but won't pass the 12-mesh forms a pile of 3FA when dumped on a plate.
Doing the same thing with a 20-mesh screen kitchen colander separates the remaining powder into 4FA (same size as FG) and meal powder. What passes through the 20 mesh colander is Meal powder. What doesn't pass through that colander is 4FA.
Four Grades of Black Powder
I wanted to end up with 12 oz. of 2FA for lifting the two 8" shells, and I actually ended up with 14.3 oz. of it. So I weighed out and set aside 12 oz, and further crushed up the extra 2.3 oz. of the 2FA, along with the 2.5 oz. of 3FA, until it was all sorted into the 12 ounces of 2FA, 4.8 oz. of meal powder and 2.75 oz. of 4FA.
I measured 1 oz. of the meal powder onto a paper plate, and put it back into the dryer to use later in the making of the spolette time fuses. I also spread the 12 oz. of 2FA lift powder out on a screen and put it back in the dryer to insure that it is completely dry when I use it.
Lift Powder Note. I've compared black powder made this way with commercial BPs. In tests performed with baseballs shot out of a 3" mortar, to produce a 300’ high flight (6.5 second flight time up and down, 4.33 seconds of fall from apogee to ground), the following powder amounts were needed:
0.35 oz. 3FA made from pine charcoal
0.45 oz. Commercial charcoal 3FA
0.55 oz. Wano Brand BP 3FA
0.75 oz. Pine charcoal 2FA
0.75 oz. Commercial charcoal 2FA
0.75 oz. Wano Brand BP 2FA
Testing with 6" dummy shells, 2 lb.-6 oz. shell weight, using 3 oz. of lift, produced the following results:
|Willow charcoal 2FA||11.06 seconds flight|
|Pine charcoal 2FA||11.65 seconds flight|
|Commercial BP 2FA||12.46 seconds flight|
|Commercial BP 3FA||13.28 seconds flight|
So, I'm confident that making BP with the SPF (spruce/pine/fir) homemade charcoal, or with commercial charcoal, produces results that are comparable with willow charcoal and commercial powders.
Note: In a future article, I'll be detailing various black powder production methods, and procedures for testing the various powders and comparing them with each other. Stay tuned.
9:00 - 10:00 am, Priming the StarsNow I want to prime one end of each star. With the black powder break charge that I'm using in these shells, these stars will probably all light without priming. But I like to be on the safe side. The primed end also adds a bit to the break, and speeds up flame propagation on the star.
I mix 0.2 oz. of dextrin with the 3.8 oz. of BP meal and wet it with some water to make a prime-slurry in a plastic tub. Using a little paint brush, or at other times dipping the end of the star into the slurry, I wet one end of each star with the prime-slurry. Then I press the wet end into the 4FA to form a rough, granular-primed end on each star. It took me an hour to prime all the stars and put them back in the dryer.
Priming the Stars with Black Powder
Star Primed with Meal & 4FA BP
Note: The method of priming stars outlined above is not my favorite or standard method. I employed it in this project to speed the process up, since the stars can be primed, dried, and assembled in the shells the same day.
My regular method of priming these 113.9 ounces of stars would be as follows:
- Make a "scratch-mix," BP prime by screening together:
Component Weight Potassium Nitrate 24.9 oz. Airfloat Charcoal 4.9 oz. Dextrin 1.7 oz. Sulfur 3.5 oz. Total Weight 35 oz.
(This is a 15/3/2/1 ratio of the ingredients)
(Referring back to Part 2 of this series, 21 ounces of BP mill-dust, including dextrin, was set aside from the second ball-mill batch. This could be used as part of the above prime. To this 21 ounces, 9.9 ounces of potassium nitrate, 1.9 ounces of airfloat charcoal, 1.5 ounces of sulfur, and 0.7 ounces of dextrin, would be added and screened into the mill-dust to make the prime.)
- Divide the stars into five lots, about 23 ounces each lot
- Divide the prime into five batches, 7 ounces per batch
- Put one lot of the stars into the star roller
Small Star Roller
(This is assuming that I'd be using my smaller, stainless-steel pot roller. If I was using my larger, cement mixer roller, I would experiment with priming 2 or 3 of the 23 ounce lots or even all of the stars at one time.)
- Out of one of the batches of prime, take 1/4 cup of the prime powder, place it in a paper cup, and add 2 tablespoons of water to it, stirring to mix up a thin prime "slurry."
- Start the star roller with the 23 ounces of stars in it, and dump the slurry onto the rolling stars, using gloved hands to thoroughly coat the stars.
- Slowly add the remaining dry prime powder out of the 7 ounce batch, 1/4 cup at a time, working the stars with the gloved hand to keep them separated, and spraying with water as necessary, until all the prime has been taken up by the stars and they have a nice, solid, "crusty" looking coating of prime on them.
- Dump that batch of stars onto a drying screen
- Prime the remaining 4 lots of stars in the same manner
Stars Primed with Slurry in Cement Mixer
10:00 am - 12 noon. Take a little break and let the stars and spolette meal powder dry completely.
12 noon - 12:30 pm, Make spolettes.
I'm making spolette time fuses for these shells, rather than using commercial time fuse, because I want to make the shell completely from scratch, using only a couple of chemicals.
Note: From Traditional Cylinder Shell Construction, Part I, Pyrotechnica IX, by A Fulcanelli, "The spolette is the oldest and most versatile type of shell fuse. It consists of a small-bored and relatively thick-walled tube, charged partially with pure commercial meal powder."
Pyrotechnica IX and XI contain the complete "Fulcanelli" series on this type of shell construction, and those of us who are familiar with this resource can't recommend it highly enough.
I have found that my homemade BP meal powder, such as that which was derived from the corned pucks above, works very well in spolettes.
My spolette tubes, which I've had for awhile, are 3/8" ID, 1/16" wall, 2.25" long, parallel wound tubes. I want 4 seconds of timing for the 8" shells, and based on Fulcanelli's figures, that ought to be about 1-3/8" of solid powder, plus 1/16" at each end for scratching back, for a total of 1-1/2."
First, I cover one end of a tube with masking tape and ram it with that amount of powder, using my 3/8" solid aluminum rod rammer, a little aluminum puck ramming base, my rawhide mallet and my 6x6 pounding post.
Ramming Black Powder in Paper Tube to Make Spolettes
I pound 1/8 teaspoon at a time, which produces 3/16" increments, until I have a solid powder column in the tube 1.5" long. Then I scratch both ends of the solid powder core with an awl to a depth of 1/16," and attach a piece of visco fuse with masking tape.
Spolette Ready to Test
Burning that spolette in a safe location, and timing it with my stopwatch, reveals a time of 3.2 seconds with this black powder. I recalculate the length of the powder core I'll need for 4 seconds, and arrive at 1-3/4," plus 1/16" inch on both ends for scratching back.
I make a spolette with 1-7/8" of powder, scratch the ends, burn it and time it, and get 4.1 seconds. Perfect. I then pound two spolettes with the 1-7/8" powder column (this takes 0.2 oz. of powder for each spolette) and scratch the inside powder with the awl. Note that the finished spolette has powder flush with one end of the tube and covered with masking tape, and leaves 3/8" of the tube still open and not filled with powder.
Note: A friend recently gave me a nice tool set for making spolettes. It is similar to what Rich Wolter makes (wolterpyrotools.com) and may have been made by him. It has been machined to work with the size tubes I am currently using. The grooves on the shaft of the ram, 1/4" apart, come in handy for gauging the height/timing of the powder column which has been rammed.
12:30 - 12:50 pm, Insert spolettes in shell hemispheres.I'm using commercially produced, Chinese, strawboard hemispheres for these shells.
My spolette has a 1/2 inch outer diameter. So, using my half inch steel punch, I knock a hole in two of the hemis, using my rawhide mallet and the 6x6 pounding post.
Punching Hole in Shell Casing
Note: Awhile back I purchased an inexpensive set of gasket punches at http://harborfreight.com/. These punches come in handy for punching holes in stuff like the shell casing above.
Harbor Freight Gasket Punches
I then hot-glue the spolettes in the two hemis, forming nice fillets of glue on both the inside and the outside, allowing 1" of the flush end of the spolette to stick out on the outside.
Spolette Glued into Shell Casing
I removed the masking tape to insert the spolette. Now I cover the outside end of the spolette with tape again, making a little "flag" with the tape for orientation during the pasting process.
On the inside of the hemi, I take a 5" x 5" piece of 40# kraft paper and make a passfire tube with three turns of the paper rolled up on a half-inch dowel. Then I hot-glue the tube over the spolette tube. I've enlarged the dowel just a bit with some masking tape to make sure the passfire tube will fit over the spolette tube.
Sighting across the plane of the hemi equator, I use scissors to clip the passfire tube off flush with that plane. I then insert two pieces of black match, making sure they fit down into the spolette tube and are pressed against the scratched column of black powder, and sticking out of the passfire tube about 1/2." I then tie the end of the passfire tube with a clove hitch, and use my awl to punch a vent into the passfire tube below the string.
Black Match and Passfire Tube Installed, with Vent Hole
Note: here's where you can see one way to tie a clove hitch knot.
The clove hitch is the most-used and versatile knot employed in fireworking, and there are several ways to tie one. At one time, I spent some time sittin’ in my LaZBoy chair, with a piece of string, and practicing the various ways of tying a clove hitch until they became second nature.
12:50 - 1:40 pm, Filling the Stars into the HemisI remove my stars from the dryer and try to pry the prime off of one of them. The prime is very hard and dry, and pulls off some of the star along with it. This indicates it is thoroughly dry and fully adhered.
I like to hot-glue my stars into the hemis with a small stripe of glue on each star, applied to the end opposite the primed end, beginning with the stars at the equator. I use four rings of 4" PVC pipe as stands for the hemis during this process.
Shell Hemisphere on 4" PVC Pipe Work-Stand
I glue the stars in about 1/8" below the equator because the angle of the hemi brings the inside edge of the stars just above the equatorial plane, where they will mesh with the stars in the other hemi.
Hot-Glued Stars around Equator of Shell
I then fill the rest of the hemis with stars, lightly gluing each one in.
Shell Hemi Filled with Stars
In a few cases I chip off edges of stars with a knife to allow a spot to be filled with another star. (I do this outdoors in a safe location.) Each hemi holds about 72 stars, for 144 stars per shell.
After filling all 4 hemis, I have 215 stars left over, enough for another shell and some rising tails. (I could have made 2/3 of the stars in the original batch if I wanted to avoid having these extra stars to dispose of. Maybe I can rustle up some more BP and make a mine or two.)
2:00 - 2:30 pm, Filling the Hemis with Burst and Assembling the ShellsI remove the burst powder from the dryer, line the stars in each hemi with tissue paper, and fill the tissue with the burst charge, clipping off the extra tissue paper with scissors. I allow the burst to project above the hemi just a bit. When I mate the two halves of the shell, I want to have to work a bit at doing so, so that, once they are mated, the shell contents are tightly packed in place.
Note: At some point, if you're like me, you'll say, "Heck, I don't need to keep that old burst powder separate from the stars with that tissue paper. I'll just dump the burst in on top of the stars and work it into the voids." Yep, that's what you'll say, and that's what you'll try, and then, after you close the shell and continue to work on it, the burst will migrate further in between the stars, and the burst and stars will start to loosen up, and the contents of your shell will start to rattle around, and your shell burst will look asymmetrical and ragged, or else the shell will flowerpot on lift (break in the mortar when it is fired).
Then you'll say to yourself, "Well, that was a good experiment and a valuable lesson learned."
And, you'll go back to using the tissue paper. Yesiree.
I then close each hemi with a circle of tissue paper, hot-glued to the equatorial ring of stars. This paper disc is easily made by taking a square of tissue paper slightly larger than the casing, folding it in half, then quarter, then eighth, etc, and then clipping the folded paper off to the right length, as shown.
Note: There has been quite a bit of conversation in pyro-circles about the safety of using hot-glue when fireworking. The heat of the glue is not a problem, being well below the ignition temperature of the commonly used compositions. The problem can arise, if and when the hot-glue gun malfunctions, and possibly emits sparks. Some pyros allow their guns to heat up, and then unplug them before gluing.
The general consensus is that the most important safety precaution when using a hot-glue gun is to keep the gun on its stand, or sitting in a "garage," like a length of PVC pipe, when it's not in use.
Hot-Glue Gun in Its "Garage"
That also keeps its innards from getting gummed up with excess glue, a common cause of malfunction. If one lays the gun down on its side while it's being used, the excess glue ends up all over it, and some ends up seeping into its bowels. My guns, when used this way are a mess. But when a gun is stored during use with the tip pointing down, either on its stand or sitting in a "garage," the excess glue just drips off the tip. The glue stays new, shiny as the day it was born, and not all gummed up inside.
It's also probably a good idea to avoid using those "dollar-store," el-cheapo hot-glue guns.
Now it's time to mate the hemis by flipping one of them over quickly and onto the other one, and then setting them tightly against each other by applying pressure with my hand and lightly tapping with my rawhide mallet. Then the hemis are secured together with high-adhesion masking tape.
2:30 - 6:30 pm, Pasting the ShellsI know what you're asking, "Does this guy ever take a break or eat?"
I am determined to get these shells pasted-in and in the dryer before dark and the beginning of the evening's festivities. And, no, nobody ever accused me of passing up on a meal.
"Pasting" a shell is the process of applying layers of reinforcing paper onto the exterior of the assembled shell hemispheres.
I mix up some wheat paste (the good stuff from pyrosupplies.com) in my blender until it is about the consistency of yogurt. Wheat paste is the old-fashioned wallpaper paste. I know, I know, how would you fellas, who are reading this, know what the consistency of yogurt is? Real men don't eat yogurt. Go buy a little tub of it and check it out. I like strawberry. (No, you cannot paste your shell in with strawberry yogurt!). But I digress.
I like to paste 8" shells with 1" x 9" strips of 40# virgin kraft paper. I have an 18" wide roll of this paper in a dispenser. I tear off twelve 9" long sheets, and do this four times, making 4 stacks of 12 sheets. I am going to use one stack of 12 sheets for each application.
I can only cut through 6 layers of the paper with my sharp knife (which I keep really sharpened). So I paste up 6 pieces of the paper on my cutting board. I apply paste to the cutting board; paste both sides of the first sheet and then lay down the rest of the sheets, feathering them as I go, and pasting only the top side of those 5 sheets.
Applying Wheat Paste to Kraft Paper Using a Paintbrush
Now, after marking my 1" widths with my marking screw-board (there are screws every 2," and I eyeball the intermediate cut marks), I cut the sheets into 1" wide strips.
Now I pick up one stack of 6 strips at a time, and lay down 9 of the stacks on top of each other, feathering the ends as I go. Then I roll them up into a little roll.
Pasted Paper Strips, Stacked and Rolled
I do this twice for each cutting board batch, and there are two of these batches for the total of 12 sheets, so I end up with 4 of the little rolls of strips.
By the way, this paper and this method require no "breaking" of the paper. (Breaking paper, as described by Fulcanelli, entails crumpling it up to incorporate the paste and break the grain of the paper.)
Shell, Pasted Paper Strips, and Wheat Paste
The first thing I like to do is to brush some paste onto the shell and smear it around with my hands, preparing the shell casing so the pasted strips of paper will really adhere to it.
I like to apply the strips in the "9 axis system" described by Jim Widmann in his PGI Bulletin article, Bulletin #123, March/April 2001. This system uses the 3 main axes, x/y/z, as well as the 6 intermediate axes, which are rotated 45 degrees from each of the main ones. The little masking tape flag on the spolette is used to keep track of the axes as the pasting progresses.
Don't worry if this is not immediately clear. I lay awake for a bit on a couple of nights visualizing all of this until the light went on inside my head. The purpose of this system is to rotate the "poles" of the layers of paper, so that the final, consolidated wrap of paper has a consistent thickness and strength.
As seen in the above photos, there are open spaces left at the north and south "poles" left after applying the 9" strips, and these poles are covered with torn strips of paper.
Each roll of strips is sufficient for one axis application, which produces 2 layers of paper on the shell since the strips are lapped by half over each other as they are applied. So, the 4 rolls are good for the first 4 axes, or 8 layers of paper.
As I apply successive layers of the paper strips, I keep the shell nice and wet with the paste, by applying a bit with the paint brush and smearing it around with my hands.
Shell, Wet with Paste, with More Strips Applied
After applying the first 12 sheets/4 rolls/4 axes/8 layers of paper to the first shell, I place it in the drying chamber, with the shell resting on two strips of wood which lie across one of the drying screens. (The shells may be too heavy to rest directly on the screen, and I don't want them sticking to it.)
While the first shell is drying a bit, I apply the first 8 layers to the second shell. The first shell has taken about an hour to paste, and it dries for an hour while I'm pasting the second shell. Once this is accomplished, I switch the shells in the dryer and make the second 8-layer application to the first shell, then switch them again, and apply the final 8 layers to the second shell. Now I have 16 layers of pasted paper on each shell.
Sometimes, if I'm getting fancy, I apply a few drops of red or green food coloring on the shell as I'm applying the last layers of pasted paper. This results in uniquely colored shells.
Note: One alternative method for pasting the shells is to use gummed, kraft-paper tape, and a tape wetting/dispensing machine. The tape would be applied to the shells in similar lengths and fashion as the pasted paper above. I like to use 1-1/4" wide, 35-40# tape on 8" shells.
Using Gummed Kraft Paper Tape to Paste Shells
6:30 pm, Two Shells in the Drying Chamber. It's Miller Time.The next and final chapter in this series will detail Sunday's lifting and leadering of the two shells. Then we can take them out to the field and put 'em up into the air!
Till then, Stay Green,
- Black Match
- Black Powder Burst
- Black Powder Meal
- Black Powder Pucks
- Cutting Board
- Dextrin (CH8107)
- Dowel, 1/2"
- Drying Chamber
- Drying Screens
- Gummed Paper Tape and Dispenser, optional
- Hot Glue Gun and Glue Sticks
- Kraft Paper, #40
- Masking Tape
- Meat Tenderizer, metal
- Paint Brush
- Paper Ball Shell Hemispheres, 8"
- Paper Plates
- Propane Torch
- Pounding Post
- PVC Pipe, 4"
- Rammer, 3/8"
- Rawhide Mallet
- Screen, 4 mesh
- Screen, 8 mesh
- Screen, 12 mesh
- Spollette Tubes
- Screen, 20 mesh (TL2002)
- Tiger Willow Stars
- Tissue Paper
- Visco Fuse
- Wheat Paste
- Zip-lock Bags