The pattern that an aerial shell paints in the sky depends on the arrangement of star pellets inside the shell. For example, if the pellets are equally spaced in a circle, with black powder inside the circle, you will see an aerial display of smaller star explosions equally spaced in a circle. To create a specific figure in the sky, you create an outline of the figure in star pellets, surround them as a group with a layer of break charge to separate them simultaneously from the rest of the contents of the shell, and place explosive charges inside those pellets to blow them outward into a large figure. Each charge has to be ignited at exactly the right time or the whole thing is spoiled.
To see how some common multibreak shells look in the sky, try the quick and easy "HowStuffWorks Field Guide to Aerial Fireworks." It's interactive, so you can click on a name and see the fireworks display that goes with it. The next time you witness a big fireworks show, you will know the names for each type of shell you see.
You can see how some of the more common multibreak shells look in the sky by clicking on the buttons in the illustration above. You can read descriptions of these shells below:
- Palm: Contains large comets, or charges in the shape of a solid cylinder, that travel outward, explode and then curve downward like the limbs of a palm tree
- Round shell: Explodes in a spherical shape, usually of colored stars
- Ring shell: Explodes to produce a symmetrical ring of stars
- Willow: Contains stars (high charcoal composition makes them long-burning) that fall in the shape of willow branches and may even stay visible until they hit the ground
- Roundel: Bursts into a circle of maroon shells that explode in sequence
- Chrysanthemum: Bursts into a spherical pattern of stars that leave a visible trail, with an effect somewhat suggestive of the flower
- Pistil: Like a chrysanthemum shell, but has a core that is a different color from the outer stars
- Maroon shell: Makes a loud bang
- Serpentine: Bursts to send small tubes of incendiaries skittering outward in random paths, which may culminate in exploding stars
For more information on fireworks and related topics, check out the links below.