The Chemistry of Firework Displays 65
Ponca City, We love you writes "David Ropeik writes at MSNBC that there's a lot more to making a basic firework display than putting a fuel source and an oxidizer together. Pyrotechnic chemists, who are trying to create bedazzlement instead of bang, don't want their work to explode, but to burn for a bit, so it gives a good visual show. To achieve the desired effect, the sizes of the particles of each ingredient have to be just right, and the ingredients have to be blended together just right. To slow down the burning, chemists use big grains of chemicals, in the range of 250 to 300 microns, and they don't blend the ingredients together very well, making it harder for the fuel and oxidizer to combine and burn, thus producing a longer and brighter effect. Surprisingly few emitters are used in pyrotechnics, and there are no commercially useful emitters in blue-green to emerald green in the 490-520 nm region. Energy from the fire in the basic fuel is transferred to the atoms of the colorant chemicals, exciting the electrons in those chemicals into a higher energy state. As they cool down, they move back to a lower state of energy, emitting light. So, you actually see the colors in fireworks as they're cooling down. To get the really tricky shapes, like stars or hearts, the colorant pellets are pasted on a piece of paper in the desired pattern. That paper is put in the middle of the shell with explosive charges above it, and below. When those charges go off, they burn up the paper, and send the ignited colorant pellets out in the same pattern they were in on the sheet of paper, spreading wider apart as they fly."
Re:Slow news day? (Score:2, Informative)
Re:A lot more (Score:3, Informative)
I don't like explosions anymore. They freak me out a little and I just don't like loud noises in general. Also, there's nothing more boring than a long fireworks display to Sousa marching music.
Maybe you should try the 1812 Overture.
Light From Fire (Score:4, Informative)
"exciting the electrons in those chemicals into a higher energy state. As they cool down, they move back to a lower state of energy, emitting light."
That's the explanation almost any time you see light, it's not unique to fireworks. It applies to any color of fireworks, regardless of whether the color is produced by the fuel itself or by the fuel heating another element. It also applies to candles, camp fires, butane lighters, acetylene torches, incandescent lights, red hot stove burners, halogen lights, etc.=.
Re:Pellet pattern? (Score:5, Informative)
Nearly all pattern shells (as they are called) are symmetric about one axis, so it normally doesn't matter. Moreover, there is little spin control, so orientation is random on burst, resulting in inverted images as often as correct ones. That's why you don't see words spelled out - you can fire shells to a particular point in the sky fairly repeatably, but you can't get them to break in a known orientation. Pattern shells are, imho, a novelty. Give me a big, sky-filling willow or diadem (long charcoal/orange legs or gold/siver flitter) that stretches to the ground any day, or a volley of big, 8" salutes. I can't stand the 3-4" salutes in finales, oddly enough - they're too "sharp" a sound for my old ears - but something big that you feel in your chest, now that's a salute!
Re:Pellet pattern? (Score:5, Informative)
Also remember for the most part, traditional fireworks involve 2 charges. There's the lift charge which gets it into the air. Then the explosive charge once it is in the air. There is a variance between when first charge goes off and 2nd. Sometimes one or both fails. Rarely but it does happen, the first charge fails but the explosive charge doesn't which is very dangerous as it explodes near other unexploded shells.
Disney is the only facility I know that uses fireworks without the lift charge. They use compressed air to launch the shells because they have a show every day and it makes their system more efficient. Also their explosive charge have timing chips which controls when they go off.
Re:A lot more (Score:2, Informative)
> Maybe you should try the 1812 Overture.
If you want more boring, try something by Johannes Brahms, or Barry Manilow.
HTH.HAND.