Pull the String
Champagne party poppers often come in packages containing dozens. You may be surprised to learn how these multi-colored, small, cheap items work. When you tug the string, the noisemaker pops, shooting a handful of clumped streamer a few feet. Champagne poppers are packed with a tiny amount of gunpowder. The amounts are so minute that champagne poppers aren't even classified as fireworks, which is why they can be sold indiscriminately in grocery stores. More powerful firecrackers are limited by federal law to 50 mg of gunpowder and under. A champagne popper has at most 16 mg.
The delivery mechanism on a party popper is simple. The string taped to the outside runs less than an inch into the handle. Surrounding the string, inside the popper's handle, is a small tube of plastic tape that fits snugly around the final inch of the string. The inside of this tube is smeared with a diluted paste of gunpowder. When the string is yanked out of the popper, the tube remains inside the popper handle. This creates a jolt of friction that ignites the champagne popper's gunpowder paste. A tiny explosion rocks the interior of the popper, which produces the effect.
Moments After the Explosion
You've yanked the string, igniting the gunpowder and sending a low-power but potent blast into the heart of the champagne popper. Amplified outward by the popper's bell shape, the explosion pushes a disc of paper outward. The festive material, forced up the barrel by the explosive force on the disc, encounters the outer wrapper: an identical disc of paper. This pops out, skyrocketing outward with the streamers right behind.