How to Make Zinc Cut Stars
Take just 20 minutes to read this article, print it out, and use it to make this firework. You will be amazed at how well it will work as long as you follow the steps we give you here. Try this project today and see if you don't agree.
Now and then on the pyro discussion lists someone will bring up the subject of zinc stars.
Usually several folks will chime in with, "Oh, man, those stars are some of my favorites,
so subtle and beautiful."
In Chapter 15 on Fireworks, of Alexander Hardt's Pyrotechnics, (this chapter written by
Barry Bush after Dr. Hardt's death), it is stated, "Good zinc stars are blue-green with
tails of delicate gold, and seem rather exotic today."
This is a color star where the color is produced by an elemental metal, rather than a
metallic salt, such as when a blue is produced with a copper oxide or carbonate. So, this
blue-green color star may be among the oldest star colors that were produced.
Back in the early 90's when I first started making stars, there was not much fireworking
information available. I was able to get my hands on a copy of the then recently reprinted
Pyrotechnics, by George Weingart. Some of my first star-making efforts were based
on a few of the formulae contained in that book, and perhaps my favorite of them was the
An added bonus is that this is one of the easiest cut stars to make that I've tried.
Granite Star formula (all parts are by weight):
|Potassium Nitrate (KNO3)
(The percentages, because of number rounding, actually add up to 101%, but that's OK, and they'll
work just fine. The percentages of each individual chemical in the composition are calculated by
taking the original number of parts of that chemical, say 14 parts of KNO3, and dividing that
number by the total number of parts, 64.5 in this case. 14/64.5=.217, which can be rounded to .22,
which is 22 hundredths or 22%.)
Note: You may be saying to yourself, "I wonder why he's including those decimal numbers
after the percentage numbers." I'll show ya in a minute. The decimals are much more useful than
Recently, Harry Gilliam, in a Skylighter Fireworks Tips Newsletter, published the formulae that he
inherited from the Kosankes when he purchased the business that became Skylighter. In that list of
formulae is one called Pearl, and it is a slightly different version of a zinc star:
Pearl formula (all parts are by weight):
I always like to look at star formulae and see how they differ from each other. It can be
seen that the second formula uses less zinc, more KNO3, and slightly more charcoal, sulfur
There is a formula in Hardt's book that is similar to the Kosanke formula above, but the
zinc is increased to 45%, and some Meal D black powder is used in it, as well as potassium
nitrate, charcoal and dextrin.
I, personally, have only made zinc stars using the first formula, from Weingart, the
In a recent discussion in the Passfire.com Forum, a fellow fireworker, who has worked quite
a bit with this star, recommended that that the charcoal used in the formula be half airfloat
and half 80 mesh. This improves the charcoal tail that the star leaves behind as it burns.
Back in the '90's when I made the star, I'd only use airfloat, so this is another area of
experimentation as an individual fine tunes the formula to his own personal tastes.
These stars light easily, especially when made as cut stars with all the corners and edges
to take and hold fire, so I've always just primed them with a "scratch-mixed" (mixed by hand,
no milling) black powder prime, simply screened through a 40 mesh screen.
Black Powder Prime (all parts are by weight):
||75 OR 15
||15 OR 3
||10 OR 2
||5 OR 1
||105 OR 21
Note: This is simply 75/15/10, KNO3/charcoal/sulfur (the classic black powder proportions),
with an additional 5 parts of dextrin added as a binder (additional 5%). One of the few
formulae that I can always remember off the top of my head is the 15/3/2/1 parts proportion
of this composition. If I want to make 21 ounces of prime, I simply weigh out 15/3/2/1
ounces of each chemical and screen them together.
How Much of this Star Should I Make?
This is a very heavy and dense star, perhaps the heaviest I have ever made. (I haven't made
stars using gold powder yet!) A 4" ball shell will use a little less than a pound of these
primed stars. A 4" mine would use about the same amount. In my small-scale, hobbyist
fireworking endeavors, I actually like making stars a pound at a time, especially when
experimenting with new formulae.
One pound of zinc Granite Stars
Using the first formula, above:
Now do ya see how handy those decimals are? Of course, any final batch size can be plugged
in instead of the 16 oz. A 32 oz. batch, or a 100 gram batch, can be calculated just as
The charcoal can be all airfloat, or it can be half-and-half airfloat and 80 mesh, as
The potassium nitrate should be milled first to make sure it's nice and fine. A ball mill will do the job but a blade-type coffee grinder works just as well and you can get them for about $10 at Walmart. Be sure to mark the one that you use for this as oxidizers only! You never want to grind fuels in the same grinder you've used for oxidizers.
What the heck is zinc, anyway? I don't know about you, but zinc is not one of those chemicals
I'm all that familiar with. In the back of my head all I kinda knew about zinc was that it was
coated onto the steel garbage cans of my youth to keep them from rusting. Galvanization they
called it. Same stuff that's on the steel ductwork leading to and from my furnace. I actually
had to look zinc up to verify that it is, indeed, an element like gold and copper. Shows ya
how much of a chemist I am.
An interesting thing about the powdered zinc that we use in Granite Stars is that it doesn't
stay powder for long. It forms clumps. Either at the supply house, or in our storage, zinc
powder will become zinc clumps, because it oxidizes in moist air.
Unless these clumps have been allowed to harden for years, they can be broken up simply by
rubbing them on a 100 mesh screen. I recently received a shipment of zinc dust which had formed
these clumps, and I was quickly able to return the metal to a dust through my screen.
Screening Zinc Clumps
Note: Zinc is reportedly not toxic, but I can tell you from experience that it is
irritating if it is inhaled during the above screening process, or during the manufacture
of zinc stars. I mean Really Irritating in the nasal passages. I'm not saying this
as some kind of CYA. Wear a good respirator when working with zinc dust. Really, no
I use a good, $25 respirator, from Home Depot which is rated for fine dusts as well as
Buy & Use a Good Respirator
Making Zinc Cut Stars
Zinc stars burn relatively slowly, and if they are made too large they will burn all the
way to the ground, especially if used in a mine. Therefore, I like to make the stars a bit
on the small side. For 4" shells and mines, I like to cut the stars 5/16" square, and once
they are primed they end up being about 3/8" square. For a more dense spray of stars, they
could even be cut 1/4" and this would work well for smaller shells as well.
I am working outdoors and away from any sources of ignition.
I have screened 21 oz. of my BP prime through my 40 mesh screen and I have it in a closed
container. I always keep every flammable composition in closed containers until they are
actually being used. This minimizes the amount of exposed materials in case there is a
stray spark or fire.
I have screened my 9.9 oz. of zinc through my 100 mesh screen.
I weigh the rest of my chemicals into individual containers, add them all together with the
zinc, and screen the complete composition 3 times through my 40 mesh screen to completely
pulverize and mix the components.
Then I weigh the composition in a plastic bucket to make sure that it totals up to the 16.1
ounces of weight that it should, thereby insuring that I didn't make any mistakes when
weighing the individual chemicals, or leave one out completely. This step can prevent a lot
of mistakes and wasted chemicals.
I put a lid on the bucket and shake it to further mix the ingredients.
Then, with rubber-gloved hands, I start to work water into the composition until workable
putty is developed. It's OK to start adding water out of a jug a little at a time, until
the composition starts to get dampened. But, the final increments of water ought to be added
by spraying it out of a little, plastic spray bottle. This prevents the addition of too much
water, which makes for a pain in the butt. It's always easier to add a bit more water than it
is to remove a little.
As I add the water, the comp will clump-up, form a hard ball, and finally, when enough water
has been worked in, it forms a nice, workable ball of dough which will flatten out smoothly
when patted with a hand. My one-pound batch of star-comp required 2.6 ounces of water to get
to this point, which is about an additional 16% (0.16) by weight.
I have two, 14" x 17," 3/8" thick, black-plastic cutting boards from Kmart or Target that I
use to cut stars on. I'll take one of the cutting boards, cover it with wax-paper, put the
star dough-ball on it, and put 5/16" spacer dowels on either side of the comp.
Then I'll flatten the ball by hand a bit and cover it with another piece of wax paper. Then,
using a rolling pin or a rocket tube, I'll further flatten the comp until it's just as thick
as the spacer dowels, 5/16" in this case.
Star Comp Dough-Ball Being Flattened into a Pancake on Cutting Board
Now, the top piece of wax paper is removed and set aside, and the spacers are removed, too.
The tub of star-prime is opened and some of it is evenly dusted onto the pancake using a
small cup or a measuring spoon.
Pancake of Star Composition, Uncovered, and Dusted with Prime
The piece of wax paper is replaced on top of the pancake. Then fold the edges of the bottom
and top pieces of paper together a couple of inches.
Folded Edges of Wax Paper
You'll see how helpful this step is in a minute.
Then place the other cutting board on top of it all, press down a bit to compress the prime
onto the pancake, and lift both cutting boards and flip them over, keeping the folded edges
of the wax paper down so that the loose prime can't fall out from between the pieces of
Remove the top cutting board and the top piece of wax paper. Now, dust the exposed side of
the pancake with prime so that both sides have been coated in the prime.
Other Side Pancake, Now Primed
Now we're ready to do some star-cutting. I love the knife that a fellow pyro turned me onto
years ago, that I use for cutting stars. It's a thin-bladed, very sharp, very straight edged,
meat-slicing knife from McMaster-Carr. It costs $26 nowadays, and is part number
I cut and filed off the little plastic handle extension that hung down below the edge of the
blade so that I could press the blade all the way down to the cutting board.
Great Knife for Cutting Stars
I start cutting the pancake of star comp into strips 5/16" wide, sliding the strips aside
and flipping them over so that the primed edges are against each successive strip.
Note: The star comp can try to stick to the knife during this process. If a strip is
clinging to the knife, it's easy to raise the knife a bit and rap its end on the cutting
board, knocking the strip downward and off of it.
Cutting the Pancake into Strips, and Flipping Them Over
Then I sprinkle more prime on the strips, put the wax paper on the strips, fold over the
edges of the two layers of paper again, put on the other cutting board, and flip the whole
deal, keeping the folded paper edges down again. The top cutting board is removed as well as
the top piece of paper, and that side of the strips is now dusted with prime.
Star prime is your friend in this process, and later on when you use the stars in a device.
Don't use is sparingly. Use it liberally. Bam. Just like that cooking guy, what's his name?
Emeril, yeah, that's it.
Strips of Star Comp Dusted on Both Sides with Black Powder Prime
The strips are now cut into 5/16" cubes, with the rows of cubes being flipped over as much as
possible to keep primed edges touching each other.
Pancake of Star Comp Cut into 5/16" Cubes.
Now, it's easy to raise the edges of the wax paper and roll the stars onto each other, breaking
up any that are clinging to each other, and fully coating all the cut sides with
I like to dump the whole mess into a large plastic container, swirl them around a bit, and
lightly spritz the stars with the water sprayer until they have fully gathered all of the star
prime onto themselves. If I get them a little too wet, I add more prime, until a nice, thick,
consolidated layer is on them.
In this instance, this one-pound batch of 5/16" stars used 6 ounces of the star
Note: The above process is actually the beginnings of a simple, hand-rolled, round star
production method. In a future article I'll use 1/8" zinc stars as the cores upon which to roll
some round charcoal stars. These zinc stars make easy-to-handle, dense star cores for this
Then I spread the stars out onto a drying screen to dry in the warm air, or to be put into the
drying chamber detailed in the Project Plans on the Skylighter
Fully Primed Stars in Plastic Bowl, and On Drying Screen
Testing the Zinc Stars
For purely scientific reasons, and not at all because I was impatient to see these babies in
action, as soon as the stars were dry, which took about a week in the open air, or a few days
in the drying chamber,
I took a few of them out and fired them out of the star testing gun. Man, they are
Testing Zinc Stars with the Star Testing Gun
Note: the 5/16" stars, which ended up being about 3/8" including the prime, worked
well in the 1/2" star-gun tube, and required a flat 1/8 teaspoon-full of FFG sporting grade
black powder to lift them. I also have some 1/2" stars which work well in the 5/8" tube, and
require a heaping 1/8" teaspoon of the lift powder.
Since cut stars may not drop smoothly into the star-gun tubes because of their edges and
corners, I use a thin dowel to push them down into the tube and to make sure they are seated
against the lift powder.
Putting the Zinc Stars to Good Use
In a Skylighter Fireworks Tips Newsletter, I used these stars to make a really
nicely performing 4" plastic ball shell.
See ya then, and Stay Green,
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Skylighter's Zinc Cut Stars Kit
With this kit you can make enough 4.5 pounds of zinc stars. Enough for 3 4-inch shells or many more smaller shells.
Our most complete star making kit ever.
- 3 lb. Potassium Nitrate
- 1 lb. Sulfur
- 1 lb. Airfloat Charcoal
- 1 lb. Dextrin
- 4 lb. Zinc
Separately all of these items would cost $87.25. By ordering the Zinc Cut Stars Kit today for $69.80 you'll save 20%.
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