Roman candle: Encyclopedia - Roman candle

Roman candle

This article is about the type of fireworks. For the 1994 album by Elliott Smith, see Roman Candle (album).

Roman candles are a type of fireworks, with long, thick paper tubes that contain layers of "stars" and lifting charges.

A Roman candle is constructed by the following method:

1. load a layer of bentonite into the tube to close off the end.
2. load a layer of lifting charge.
3. load a pyrotechnic star.
4. cover the assembly with a dusting of black powder.
5. load a layer of delay powder.
6. repeat steps 2-5 until tube is full

The device is ignited from the top. The delay powder is packed tightly in the tube, so that the flame cannot reach around the sides of the plug of delay composition. It therefore burns slowly; as it is consumed, the flame moves down through the tube. When the flame reaches the topmost pyrotechnic star, the star is ignited. Because the star fits loosely in the tube, the fire spreads all around it and ignites the lift charge. The lift charge burns quickly, propelling the star out of the tube, like a bullet from a gun. In doing so it also ignites the layer of delay powder beneath it, and the process repeats.

There are several variations on this:

• Many Chinese Roman candles use clay instead of delay powder and run a length of fuse down the inside of the candle to time the lifts.
• Larger Roman candles will usually add more lift to the highest layers and less to the lower layers in order to cause the stars to lift to the same altitude.
• Some really large candles will load comet shells instead of stars.

Roman candles are banned in for example Finland due to them being considered prone to accidents.

Category: Fireworks

Adapted from the Wikipedia article "Roman candle", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki