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United States Science

The Chemistry of Firework Displays 65

Posted by Soulskill
from the two-parts-oooh-one-part-ahhhh dept.
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."
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The Chemistry of Firework Displays

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  • by Anonymous Coward

    Tonight I will welcome our tricky shaped overlords.

    and some beer...

  • Slow news day? (Score:1, Insightful)

    by xlotlu (1395639)

    Slow news day? Or is this a new "educate-the-readers-in-things-they-don't-care-about" program?

    There is no news in the article... It sounds like something a student would copy off wikipedia, mingle a bit, throw in some metaphores, and turn into a school essay.

    Did you mean idle? It's posted under news...

    • July 4!! (Score:5, Insightful)

      by PleaseFearMe (1549865) on Saturday July 04, 2009 @07:41AM (#28579441)
      It's July 4. I'm going to watch fireworks today, so Slashdot posted something about fireworks.
      • Re: (Score:2, Flamebait)

        by xlotlu (1395639)

        It's July the 4th every year.. in July.. on the 4th.

        And it's kinda sad that if one needs to write something about Fourth of July, all they can come up is with some musings about how difficult it is to make fireworks, and then it gets labeled as news.

        It's your Independence Day ffs. Ah, but you have shiny colored things that go boom in the sky; that's way more interesting than history. And hey, it can make it on slashdot's front page too...

        • I'm with you man...there is nothing worse than a silly story actually labeled as NEWS when it should have been under idle or education!!! You have to be kidding me...It's absurd. It's a complete waste of our time.

          The only thing I can even think of that could be worse is spending time commenting on a story I thought was silly and a waste of time. Now that would be really silly.

          • I'm enjoying the discussion of pyrotechnics. The significance of Independence Day, especially in this day and age, is just too depressing to think about. Besides, I already blogged [blogspot.com] about the other stuff and it's killed my celebratory mood. Let's enjoy some big colorful lights and loud noises.

    • Re: (Score:2, Informative)

      by LoztInSpace (593234)
      The USA flag on the story is a bit misleading too. I am fairly sure that fireworks were invented in China long before the USA existed.
      • Re: (Score:3, Funny)

        by zarzu (1581721)
        it's not chinese fireworks, it's freedom fireworks!
        • Freedom (Score:3, Funny)

          by PleaseFearMe (1549865)
          Freedom from Britain _and_ Freedom from work yesterday!
        • Re: (Score:3, Insightful)

          by Opportunist (166417)

          Hmmmmmm....We make a lot of noise about it and we watch it go up in smoke, even enjoying it when we don't really think about it, while costing a fortune, but in the end we got nothing but a big show...

          Yup, freedom fireworks is quite apt.

      • by jonadab (583620)
        > I am fairly sure that fireworks were invented in China

        Maybe so, but showing more fireworks on July 4th (and the adjoining days, especially if it's a weekend) than the rest of the year combined is definitely an American concept. The story was flagged with a US flag because it directly pertained to a US holiday.

        In China, they probably do fireworks in wintertime for Chinese New Year or somesuch, but I'm pretty sure they don't celebrate the signing of the Declaration of Independence.
    • Re:Slow news day? (Score:5, Insightful)

      by Opportunist (166417) on Saturday July 04, 2009 @08:07AM (#28579557)

      Show me ONE geek that does not care about shiny things that go boom!

      • Matthew Weigman [dailytech.com]? Or how about Joe Engressia [wikipedia.org]?

        Both legally blind (so no interest in the shiny shiny) and fireworks without the shiny are just annoying to listen to.

      • Though not really applicable to general category of "shiny things that go boom", definitely true in the case of fireworks.

        Really, why do people feel the need to propel thousands tons of chemicals into the air and just let them explode?

      • by rdnetto (955205)

        Show me ONE geek that does not care about shiny things that go boom!

        Well, that rules out the Sony fanboys. *ducks*

    • Re:Slow news day? (Score:4, Insightful)

      by tedgyz (515156) * on Saturday July 04, 2009 @08:53AM (#28579793) Homepage

      Chill out dude! You don't have to read the article and the small space used on the /. front page is not going ruin your day.

      Maybe some of us actually care about how fireworks work. That is a natural geek tendency. What's so wrong with that?

  • "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.

    I agree. For the real fun, you need something to blow up. Mythbusters isn't popular because the grenades they use produce nice colorful images upon exploding inside that fridge.

    • I used to work in a fireworks factory. Few months after I quit that job and went to sea, it blew up. The people who were vaporized didn't find it much fun...
    • by Beorytis (1014777)

      For the real fun, you need something to blow up.

      Like this [suntimes.com]?

      "District lieutenant said the explosion ... appeared to have been a prank."

      Ya think?

  • Pellet pattern? (Score:3, Interesting)

    by michaelmalak (91262) <michael@michaelmalak.com> on Saturday July 04, 2009 @08:34AM (#28579657) Homepage

    the colorant pellets are pasted on a piece of paper in the desired pattern

    Not being an explosives expert, but wouldn't the pellets be pasted on in the inverse of the pattern -- i.e. 1/r in polar coordinates or some such?

    On a barely-related note, I was surprised to learn after having moved to Denver that not only are 100% of consumer fireworks banned, but there are also no free professional fireworks displays either (though there are several where you pay for admission). You have to either go on July 3 (missed it) to a park or go to an adjacent city (Aurora, Westminster, Boulder, etc.).

    • Re:Pellet pattern? (Score:5, Informative)

      by Overzeetop (214511) on Saturday July 04, 2009 @08:44AM (#28579727) Journal

      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!

      • Hmm... and here I was thinking if you can feel the salute in your chest they loaded the wrong ammo...

        • Re:Pellet pattern? (Score:5, Interesting)

          by Overzeetop (214511) on Saturday July 04, 2009 @10:32AM (#28580397) Journal

          I've been present for a 5 gallon bucket full of flash powered being ignited, about 1000-1500' away*. That's about the equivalent of a 12" salute, I believe. It was an awesome "holy shit" moment. Unfortunately, some of the crowd were not aware of that part of the display, and there were gasps and not a few people sobbing immediately thereafter, fearing that something had gone wrong. Even at that distance, the fireball warmed your face and body, and the thump was felt to your toes.

          *The Pyrotechnics Guild International 1994(?) convention in Pennsylvania - all licensed and legal. It may have been a bit further, and my memory has it "just across the lake."

      • Re:Pellet pattern? (Score:5, Informative)

        by UnknowingFool (672806) on Saturday July 04, 2009 @11:01AM (#28580605)

        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.

    • by Deadstick (535032)
      I was surprised to learn after having moved to Denver that not only are 100% of consumer fireworks banned

      OTOH, you can buy all the big mothers you want 100 miles up the road at the first exit in Wyoming, which supplies enough ordnance to keep the Denver ER's nice and busy.

      You have to either go on July 3 (missed it) to a park

      ...where we had half a dozen people injured by a short round a few years back...

      rj

    • by sjames (1099)

      Since they are placed in the break charge, their final distance will be roughly proportional to their starting point rather than inverse. The further out it starts, the more charge is 'behind' it and the less in front of it when it breaks. A star dead center in the shell wouldn't be propelled at all (in a perfect world).

  • Light From Fire (Score:4, Informative)

    by Jedi86 (765527) on Saturday July 04, 2009 @08:34AM (#28579665) Homepage

    "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.=.

    • I don't know how blackbody radiation is generated, if not from electrons dropping into lower energy states, but isn't it possible to get blackbody radiation from materials completely lacking electrons? Even for normal materials hot enough to glow, how do you get the essentially-continuous spectrum of blackbody radiation?

      • Blackbody radiation is an approximation, assuming that a material can emit a spectrum of photons of different energies. All light is a result of moving charge, most commonly from electronic transitions, and when you take into account the actual quantum physics of an atom or group of atoms (macroscopic material), you won't get actual blackbody radiation. For example a perfect (pure) semiconductor at a high temperature will not emit light with energy less than the band gap energy, but for energies above the b
      • by Jedi86 (765527)

        My mistake... I was describing luminescence (electron jumps) but the examples were incandescent (thermal vibration of atoms). It's still the "cooling" that you see, whether it be excess energy from the atom or the electron.

        http://library.thinkquest.org/27356/p_sources.htm

  • 4th of July (Score:1, Insightful)

    by Anonymous Coward

    233 years and still leaving naysayers stumped like rain forests!

    Now let's take it back to what it stood for those 2 centuries ago and throw the Democran and Republicrat bums out.

  • Someone might enjoy these two programs which allow fireworks-like effects: http://dan-ball.jp/en/javagame/dust/ [dan-ball.jp] http://powder.unaligned.org/ [unaligned.org] http://www.youtube.com/watch?v=MESkoRgSeJo [youtube.com] http://www.youtube.com/watch?v=Jdf2JSKHWe0 [youtube.com]
  • ... and explain the chemistry behind the ones that make the big bangs around my neighborhood. The ones that sound like ordnance stolen off the nearby military base.

    • Re: (Score:2, Interesting)

      by jonadab (583620)
      > explain the chemistry behind the ones that make the big bangs

      As a general rule, I think the main active chemical ingredient in those is plain old smokeless powder (which you can easily look up on Wikipedia if you're curious, so I won't duplicate all the details here).

      What's more interesting to me is the physics behind the boom. It's very similar to the physics behind thunder. Sudden temperature changes cause a rapid change in volume (Charles' Law in action). The resulting movement creates a sound wa
      • by Muad'Dave (255648)
        I'm fairly certain that they use black powder [wikipedia.org], which provides a large 'thump' without requiring containment. Smokeless powder [wikipedia.org] does not detonate, it just burns rather vigorously. If it's not contained, you get a rather disappointing whoosh. Black powder, OTOH, goes boom with or without containment.
    • OOooh... Sorry sir, that'd be me, we'll take our mortars and shuffle off your lawn now. (C'mon you have 364 days out of the year where I'm not blowing up your neighborhood.)
  • I used to get a kick out of just flushing an explosive device down a toilet. The crap flies out in a pattern determined by this mathematical formula...um...I had it just a moment ago.

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