At the darkest time of the year, candles are an important symbol of hope and life in this month’s Jewish celebration of Hanukkah, Christian celebration of Christmas, and in the celebration of Kwanzaa.
Fire and light are part of many traditions and ceremonies the world over, as the warmth and illumination of flame have come to symbolize joy, truth, and love. For Buddhists, Hindis, Jews, Christians, and nearly every other cultural group of people, candles are a way to bring those symbols into their homes, to their dinner tables and Christmas trees, to their weddings and funerals – to those celebrations that express the greatest feelings of the human spirit.
Over millennia, candlemaking has evolved considerably, and today color and fragrance are the two qualities that influence most shoppers as they select which candle to buy. The chemistry of how well a candle burns, however, is determined entirely by two factors: the wax and the wick. And it is with regard to these two aspects that the greatest improvements have been made.
In the Middle Ages, candles were most often made of tallow from animal fat; these candles emitted soot and were smelly, as well as being fairly fragile. Much cleaner-burning beeswax candles were introduced, but their high cost made them impractical for routine domestic use. In colonial times, American settlers discovered that wax derived from bayberries burned cleanly in candles and gave a pleasant aroma. The growth of the whaling industry in the late 18th century also spurred the development of candles made of spermaceti wax, which was harder than tallow or beeswax and therefore did not bend or melt in the summer. Modern candles are commonly made from paraffin wax derived from petroleum or animal fat-based stearin wax, although candles made from soy wax are becoming more popular.
When a candle burns, the heat from the flame vaporizes a small amount of wax, and it is that vapor that undergoes combustion. More wax is drawn up the wick via capillary action to ensure a constant rate of combustion. The size, shape, and material of the wick must be chosen for each specific candle to ensure that the flame does not get too much fuel, resulting in lots of soot, or that the flame does not get too little fuel and go out. The best wicks are braided or knitted, although twisted wicks that feed fuel quickly to the flame are often used in birthday candles.
Most candles also contain a combination of fragrance and dye to make them attractive accents for a given room or table decor. Although there is no chemical requirement to do so, dye and fragrance are generally matched to meet consumers’ expectations; so a vanilla candle is likely to be white or cream colored, and a balsam candle will be some shade of green.
The National Candle Association has more information about candles on their site, http://www.candles.org/index.html