There’s something about the flickering flame of a candle that we seem to find irresistible. When we want to create a special mood, or a feeling of warmth and hominess when the weather and the world are cold and frightful, we light a candle–but we seldom meditate on its history and science. As usual, I’d like to change that.
A candle, the encyclopedia tells us, is “an illuminating device made of a fiber wick enclosed in a cylinder of wax or fatty material.” Without that “wax or fatty material”–the candle’s fuel–the wick would flare up and burn down in a matter of seconds. The fuel burns more slowly and more brightly than the wick would by itself, although some of the fuel may not burn completely; instead, it melts and runs down the sides of the candle.
Beeswax candles were probably the first candles; they were used in Egypt and Crete as early as 3,000 B.C., and the Romans used them, too. (The word “candle” is derived from the Latin word “candere,” meaning “to shine.”)
In Europe in the Middle Ages, tallow candles were most common. Tallow (animal fat) candles were cheap. They were also very smoky and smelly, because animal fat doesn’t burn nearly as cleanly as beeswax.
The earliest candles were made by dipping a wick into melted wax or fat, then pulling it out and letting it cool and solidify in the air. The candle could be dipped over and over again until it was as thick as was needed. Taper candles, used primarily in churches, are still made this way. (The custom of putting candles on birthday cakes comes from the medieval practice of giving a child a taper during baptism.) Medieval beeswax candles were made a little differently, by pouring melted wax over a suspended wick.
Candlemaking changed over the years, albeit very slowly. A French inventor created wooden molds in the 15th century as an alternative to dipping, and in the 1700s, spermaceti, a slow-burning substance from the heads of sperm whales, was introduced.
In 1811 Michael Chevreul of France discovered a way to separate a substance called stearin from animal fat. Patented in 1825, stearin–used today in everything from margarine to soap to medicine to explosives–became a major new fuel for candles, cheap like tallow but cleaner-burning. Since the mid-1800s, most ordinary candles have been made from various mixtures of paraffin wax, stearin and beeswax.
Also in 1825, someone got the bright idea of braiding the wick. Braiding allowed more oxygen to come into contact with the wick’s fibers, so that the wick burned completely, leaving very little ash. As well, the braiding caused the wick to curl, so that any ash that was produced fell off. Before that, candle and lamp wicks had to be trimmed regularly. (As often happens, the new technology cost jobs: before that, villages used to employ wick trimmers, who went about on stilts to trim the wicks in the streetlamps.)
In 1834, a candle-molding machine was invented that formed the basis for today’s candlemaking machines, in which candles are formed in rows of molds threaded with spools of wicking, then ejected by pistons.
No matter what a candle is made of, or how it is made, the most important thing about it is its flame. A candle flame consists of a layer of hot gas surrounding a tapering column of cool, unburned gas (the dark area immediately around the wick). The light in the brightest part of the flame comes from glowing but not-yet-burning carbon particles. In the outermost layer of the flame, the carbon (now in more direct contact with the oxygen in the air) also burns. That results in less light but more heat.
A candle flame forms an upright tongue both because hot gas rises and because the air above it expands as it is heated, creating a partial vacuum over the flame that sucks the flame upward.
Today, candlemaking is a sizable but rather minor industry. It’s unlikely anyone is going to emulate the success of William Procter and his brother-in-law James Gamble, who, in 1837 Cincinnati, began peddling candles in the street and up and down the Ohio River. They grossed $50,000 their frst year, and their company, Procter and Gamble, is still going strong.
Still, in some ways, candles have seldom been more popular; we dine, worship and celebrate by their light. Although they’re no longer our only way to banish the darkness, they continue to illuminate our lives–just as they have for 5,000 years.
