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by Dr. Oneida Cramer
Trailing behind the popularity in burning scented candles is an ominous cloud of soot, dust, and ghosting (dark shadows) on wall surfaces, carpets, heating and air conditioning filters, blinds, drapes, television screens, and computer monitors. According to the latest evidence in this hotly contested controversy, the most likely culprit is the candle.
?You can burn candles and not have a bad problem,? says Vicki Chase, who has viewed the development from two vantage points?her own candle-making business, Top It Off, and as marketing director of Frymire Engineering Co., where the problem presented five years ago.
?I would get calls from customers saying ?I?ve got something coming out of my air conditioning vent,?? Chase said. ?For the longest time, our company was taking the brunt, thinking something was wrong with the air conditioning equipment. Once we started investigating, we knew that the customer?s air condition system was fine.? Finally, Chase went into the homeowner?s house, where she found candles burning all the time. So, Chase performed an experiment. She asked the homeowner to extinguish the candles and rub a white cloth over the TV. The cloth picked up a black substance-soot. Chase also found soot throughout the house. After cleaning up the soot, Chase had the woman relight the candles. Again, they rubbed the TV with the cloth and collected more soot?to the surprise of the homeowner.
Some candles burn dirty or are more likely to manufacture soot, according to Polly Sprenger in Home Energy Magazine, the publication that first described the problem in January 1998. In fact, the story behind candle making is a story about finding a clean burning candle.
The Romans, who are credited with inventing candles, relied on tallow from cattle or sheep suet, which produced a smoky flame and acrid odor. Clean burning beeswax was introduced in the middle ages but was too expensive, except for the wealthy. Not until 1850 did candle makers come up with paraffin wax, a bluish-white, clean burning wax that was also economical. Once paraffin?s low boiling point was corrected with stearic acid, paraffin and stearic acid became the basic ingredients in candles. Today, most candle waxes are combinations of large paraffin waxes (a carbon that?s fully saturated with hydrogen), beeswax, and additives for flame luminosity, scent, and ease of manufacturing.
Candles are not rocket science, says David L. Urban, combustion engineer at NASA. Basically, they?re comprised of solid fuel (wax) and a wick running through the center. Once lit, the flame creeps down the wick until it touches wax, where the heat melts the wax around the base of the wick. Through capillary action, the melted wax is drawn into the wick and then inside the flame, where liquid wax vaporizes into a gas. The gaseous wax enters the combustion area of the flame to become plasma before being converted into energy and heat. Incompletely combusted carbon (soot) emits the bright luminous yellow color in the flame. Most soot is fully combusted inside the flame. But when partially combusted carbon leaves the flame, it becomes smoke/soot. Incomplete combustion occurs when the wick is oversized, or the wax contains too many compounds or access to oxygen is limited.
For instance, an oversized wick absorbs lots of wax, which makes a large flame. But the flame can?t combust all the carbon, and smoking occurs. Wick size is a function of thickness and length. The homeowner can control the length of the wick by always trimming it ? inch above the wax. The manufacturer determines the thickness of the wick, which is made primarily of cotton fibers, bundled or braided in different sizes. Some candles have metal in their wicks, primarily zinc-core, as a stiffener or to slowdown burning. But sometimes, that metal is lead.
In a study conducted February 2000 in the Baltimore-Washington area and reported in the July 12, 2000 Journal of the American Medical Association, the team of Howard Sobel, Peter Lurie, and Sidney Wolfe purchased 285 different candles from 11 chain stores to find that 30% of the candles contained metal core wicks, 10% of those being lead core. Jerome Nriagu at the University of Michigan School of Public Health examined lead emissions from 15 different brands of candles made in the US, Mexico, and China. After burning the candles in an enclosed space (12 feet by 12 feet by 10 feet) Nriagu found that some candles raised the levels of lead in the air above the minimum recommendations set by the US Environmental Protection Agency (http://unisci.com/stories).
To determine if lead is in the wick, the National Candle Association offers a test. Rub a piece of white paper over the unburned candlewick. If lead is present, the wick will leave a gray pencil mark on the paper.
Since early 1990?s, the candle industry has grown at an average annual rate of 10-15% until recent years, where growth has doubled, according to the National Candle Association. Candles are used in 7 out of 10 households; typically, each manufacturer makes from 1,000 to 2,000 varieties and types including tapers, straight dinner candles, spirals, columns, votives, wax-filled containers, and novelty candles. Color, shape, and scent are the most important factors in selecting a candle although fragrance is becoming increasingly important. Publications suggest avoiding soft candles and candles that are greasy to the touch to curtail excess smoking. Also, don?t burn scented candles around food, which may take on the scent.
In the wake of this controversy, Chase, along with daughter Heidi, has developed a line of candles that are hand made and custom scented. And Chase hosts candle parties on Saturday afternoons from September through May. For information about parties or about candles, contact Chase at 972-367-2764 or e-mail firstname.lastname@example.org.
When burning a new candle for the first time, Chase recommends burning only 30 to 45 minutes. Put the flame out with a snuffer, and allow the pool of wax to harden. Clip the wick, and relight. Burn for 2 to 2 ? hours. Repeat.
Additional Tips for Burning Candles
1. Keep wicks trimmed to ? inch.
2. Keep wax pool free of foreign matter such as matches and wick trimmings.
3. DO NOT place candle in drafty areas, i.e., ceiling fans, air conditioner vent, opened window.
4. Do no burn candle more than 2 to 2 ? hours at a time. Allow wax to harden, trim wick, and relight.
5. NEVER leave a burning candle unattended.
6. NEVER leave a child, people with disabilities, or pet alone with a burning candle.
7. Always use candlesnuffer to put out flames.
8. Do not burn candles near flammable materials or objects.
9. Burn candle in proper container or candleholder. Do not place candle directly on surface of furniture.
Dr. Oneida Cramer
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