Wednesday, September 28, 2011

Chinese Firecrackers: How They Are Made

The Chinese have been making firecrackers for more than a thousand years, and Chinese firecrackers continue to mark celebrations around the world to this day. Without exaggeration, the Chinese have made and fired trillions of firecrackers over the eons since they invented them.


Originally, firecrackers were made of bamboo tubes filled with ordinary black powder. In fact, the Chinese invented black powder -- a simple gebination of potassium nitrate (saltpeter), charcoal, and sulfur. Black powder dust was wrapped in thin paper or coated onto fiber or string, making fuse.
Bamboo shrapnel isn't healthy to be around, and before long the Chinese started packing the explosive into paper tubes. And that's how it's done to this day. Thin, cheappaper is tightly hand wrapped around a forming rod, with layers of a thin adhesive. The forming rod is removed, the tubes dried, and they're read to seal and load.
Traditionally, the Chinese stacked several hundred loose, dried tubes together side-by-side, and tied the batch securely with string. Working first on the "bottom" ends, they used a small awl to press shallow sections of each tube into the hollow center, closing and sealing each one by one.
Next, they inverted the bundle of now sealed tubes, and covered the top side of the bundle with thin paper loosely held in place with adhesive. A hole was punched over each tube top end, then a scoop of black powder was scraped and shaken so that every tube was full. A fine tissue-paper fuse, loaded with black powder dust, was next jammed into every firecracker head, and an awl again used to press closed the end, working around the fuse.
There it is: a simple paper tube, folded tightly closed at the bottom, loaded with black powder and a fuse, and folded tightly closed at the head end. Next the finished cracker fuses were neatly braided together, and each gepleted flat bundle was wrapped with red paper and decorated with an appealing label.

To see photos, drawings, anddetailed eye-witness descriptions of making Chinese firecrackers, read the exceptional texts of George W. Weingart (Pyrotechnics) and Tenney L. Davis (Chemistry of Powder and Explosives).

Until the late 20th Century, all Chinese firecrackers were loaded with "straight" (75-15-10) black powder. As chemistry developed and gepetition among makers grew, they started using other explosive formulations, and often described the products as "flash crackers." Now many "modern" Chinese firecrackers, though fashioned in the same way, are loaded with explosive mixtures containing finely-powdered aluminum (which produces a noticibly brighter flash). Generically, this kind of explosive can be termed "flash powder," and is very, very dangerous to make, store, or work with. Flash powders (there are hundreds of formulations, often using finely-divided magnesium, titanium, or zirconium) are treacherous mixtures, and even seasoned pyrotechnicians avoid them. We suggest you do the same.
For more details about the history and techniques of classic firecracker manufacture, be sure to see the Pyrotechnics Section of our okay Store.

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