How to Make Flashing Fireworks Strobe Pots

Written by Harry Gilliam

Topics: How to Make Fireworks

 

 

Close your eyes and listen to this music. What do you see when you do so?

Click here to listen to The Who

If you don’t see a large fireworks mine-shot, followed by a line of 30-second strobe pots, ending with another large mine-shot, then you really need to be subscribed to the Quilting-101 newsletter instead of this one on making homemade fireworks.

Man, that music gets me in the mood for strobes. The first mine-shot would grab the attention of any fireworks-display audience. Then the soft and subtle section of strobes would calm them down and get them ready for their emotions to build during the show.

Strobe pots are among the simplest of fireworks devices and are easy to make. They can really add some of that low-level variety to a pyro-display that so helps to keep an audience’s attention.

“Hey, here’s something different,” they’ll say to themselves as they stop, settle in, and start to pay attention.

 

It is not necessary, of course, to have a scientific understanding of strobes in order to make them. Like baking a loaf of bread, chemistry is not necessary. All you need is a recipe, the right ingredients, and a feel for the proper ways to manipulate those ingredients.

But, for the scientifically minded, there are a few informative resources, which explore the strobe phenomenon in depth. In the 1979 edition of Pyrotechnica, Number 5, Robert Cardwell, the editor and publisher of the Pyrotechnica series, wrote an article, Strobe Light Pyrotechnic Compositions: A Review of Their Development and Use.

In this essay, Cardwell explores the historical development of strobing compositions and presents quite a few different formulas.

Dr. Takeo Shimizu, in Fireworks, the Art, Science and Technique (FAST), originally published in 1981, writes about “Twinklers,” which is how he refers to strobing stars. He presents an outline of the development of these strobing compositions, progressing during the second half of the 1900′s.

Specifically Shimizu writes, “In Germany, U. Krone and F. W. Wasmann suggested that a twinkle composition consists of two kinds of compositions mixed with each other, i.e. a smolder composition and a flash composition-Ammonium perchlorate smolders when it is mixed with a small quantity of magnesium. This can be used for the smolder composition. A mixture of magnesium and sulfate flashes when it is heated to a high temperature. This can be used as the flash composition.”

So, interestingly, a strobe composition is actually a mixture of these two types of comps, a smoldering one and a flashing one. When the mixture is lit, the first one begins to smolder. When the heat rises high enough, the flash comp ignites and emits a flash of light and heat. Then the mass returns to the smoldering state until the heat rises high enough to repeat the flash.

In some compositions, magnesium-aluminum (magnalium) is used instead of the magnesium. Magnesium requires a coating to prevent it from prematurely reacting with the oxidizer in the comp.

Additionally, sometimes barium nitrate or other oxidizers are used instead of ammonium perchlorate.

In 1987, John “Skip” Meinhart offered some details about his noteworthy strobing star formulas in Pyrotechnica XI. Except for Shimizu’s White formula, and Skip’s Pink formula, all the rest of the formulas use magnesium as the metallic fuel ingredient.

In the 1992 Pyrotechnica XIV edition Jennings-White explores Blue Strobe Light Pyrotechnic Compositions. Up until that point in time, blue strobes had not been explored in depth because of some unique problems associated with the chemical mixtures required to produce that color in a strobe.

All of this information ought to be able to keep you reading until late into the night if you are so inclined.

 

I won’t be focusing on making strobing stars in this project, but only simple, ground-effect strobe pots.

I’m also not going to be making any of the formulations, which contain magnesium. As I said, using that metal requires a special coating process because it does not form an oxidized protective layer on its own, as do aluminum or magnalium.

There seems to be some debate as to whether or not magnalium needs to be treated and coated when it is used in compositions containing ammonium perchlorate. Meinhart states, “I have had success using magnalium powders that have not been treated with potassium dichromate. In practice I have often used treated metal powders, but this does not always seem to be necessary.”

Whereas in Hardt’s Pyrotechnics, Barry Bush notes that the formulas he cites which contain magnalium or magnesium in combination with ammonium perchlorate do “require the metal powders used to be treated with potassium dichromate.” Shimizu also specifies treated magnalium, and details the methods of treatment in FAST.

Shimizu does state that if there is any reaction between magnalium and ammonium perchlorate, which would be encouraged by the presence of water, it would only be a slow reaction in which the metal is affected gradually.

I have used untreated magnalium in these formulas, with no problems. One sign of an unwanted reaction would be the heating-up of the composition as I’m working with it, so I always pay attention to see if that is occurring. I avoid adding any water to such a composition. I also don’t store these devices for long periods of time, which could produce a slow reaction of the ingredients, especially in the presence of moisture.

So, I think I’ll make simple white and pink strobe pots. The white formula is the most commonly cited one.

Click here to learn this how to make bright flashing strobe pots.

3 Comments For This Post I'd Love to Hear Yours!

  1. A. Chemist says:

    “Like baking a loaf of bread, chemistry is not necessary.” The intent of this article is to explain how to make strobes and why strobes work, yet you insist that even a basic understanding of chemistry isn’t necessary. It’s especially ironic that you feel the need to use vocabulary associated with chemistry in light of this assumption. Additionally, you are suggesting that a blissful ignorance of chemistry has no effect on your personal safety when making fireworks. The difference lies in the fact that when you mix flour and sugar, you don’t have a damn explosion hazard like you would with mixing a fuel and oxidizer. Consider first sulfur and a chlorate salt. Without proper knowledge of why these chemicals are incompatible, your life expectancy drops considerably. You fail in explaining how and why these fireworks work, and you attempt to provide instruction to the public in a dangerous manner. Aside from the aforementioned quote, this article is highly misguided and poorly written. It is an embarrassment.

  2. Max says:

    I finally got my hands on Am.Perc. And was able to try the white strobe comp using barium sulphate.

    With the comp I used my star pump to pump about 50 pellets of the comp. but also decided to fill a 4″ long 1″ diameter tube. The pellets burned very well and lit with a BP/NC lacquer prime. They burned for about 10-15 sec each.

    However the tube filled started out great, and started to sound like a helicopter flying above and all of a sudden about 1/4 of the way in BOOM! Part of the tube and base lay on the concrete in flames a small amount strobes and fizzles away about 3 feet away. I hear something hit the side of my garage about 30′ away.

    Any idea what caused the strobe to fail catastrophically? I’ve seen this happen once before with a consumer strobe I purchased many years ago.

    Thanks

  3. G.low Pyro says:

    Could you modify this formula to make just a single flash. Much like the flash powders without the “bang”. My guess, correct me if I’m wrong, would be to nix the nitrocellulose then add more charcoal or lamp black….

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