The science and art of pyrotechnics

Like millions of other Americans, my younger son and I watched a fireworks display last night. I won’t agree with him that it’s the best part of the 4th of July, but it is fun to watch. Having him with me also made me take a new interest in the different shapes and effects and how they were made.

He asked at one point, “Which do you like best?” I hadn’t thought about it, and started paying closer attention to pick one out. There’s the kind where there are parts that keep twinkling as they fall in trails down through the sky, there are the ones that have different colors in a specific pattern (such as a red line across a blue circle), and there are the ones where at first nothing much seems to happen, but then there are a whole lot of white swirly twinkly patches with a tinkly sound rather than a boom.

I’m sure all those shapes and effects have names, but I had no idea what to call them, and it’s hard to say what you like when you don’t know what to call it. And I didn’t want to detract from the pleasure of just sitting and watching the beautiful display by saying how well I liked particular ones as they appeared.

He also asked, “How do they work?” I realized I really didn’t know much about that except that they use gunpowder, and they start off in paper tubes that, if you should find one that didn’t fully explode lying on the ground, you don’t want to pick it up. But I knew we could easily enough find out the answer at home, whether from the internet or one of our “how things work” books.

We ended up going to the library today, so we took a look at a book on fireworks there – the only one left (in the children’s section) that hadn’t already been checked out. He got a very rough idea of how they’re made, which satisfied him, but I wanted to know more. I particularly was interested in knowing how in the world they made the smiley face firework. (It came out sideways, but was still instantly recognizable as a smiley – something I’d never seen before or imagined possible in a firework.)

Apparently it all has to do with the arrangement of the color “stars” inside the aerial shell. This example shows how a star would be made, which we didn’t see any of last night, but I’m sure the same principle would be used to make a smiley face. They just have to also make the eyes and mouth of different colors to emphasize the effect of a face.

Another website shows how the different colors are made, by heating different metal salts. This same site also explains why fireworks appear to be two-dimensional, although they are in fact exploding in three dimensions. And HowStuffWorks does a good job of explaining other aspects of the history, manufacture, and use of fireworks. It even includes an interactive section to help you learn the names of different shapes that fireworks can make. (One of my favorites is the willow.)

I think some of the delight of watching fireworks is their apparent magic, making such unexpected colors and shapes in the sky. I hope that knowing a little more how they work now will increase my admiration for the people who make them, without reducing my pleasure in watching them in the future.


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