Q: Does the colour of a candle determine whether it will burn faster? Is there some ingredient that makes it burn faster? Jason, Avilla, Indiana, USA
Colour makes no difference how fast a candle burns. "Black candles burn no faster than white," says chandler Stefan Phillips of the Island Candle Company.
Wick size is the primary factor determining candle-burning rate. "A larger wick is like stepping on the gas pedal," says Phillips. The big wick delivers more fuel to the burning flame.
By the way, a candle is a cylinder of solid fuel - paraffin wax - that surrounds a wick. How does it burn? Bringing a lit match to a wick melts and then vaporizes the wax coating the wick. The wax vapour combines with oxygen, and burns.
Wax is the most important ingredient that makes a candle burn faster. Soft wax has a higher oil content and lower melt temperature; therefore, it burns faster. Typically, candles in jars have soft wax, and pillar candles have hard wax. The longest burning candles are pillar candles made of a blend of beeswax and paraffin.
Burning tips (from the Island Candle Company)
- Trim your wick to 1/4 inch or less before you light a candle. Long wicks burn inefficiently and may smoke.
- Protect your candle from drafts, which can blow the flame to one side, and cause molten wax to run down the side of the candle. A dancing candle flame indicates a shortened candle life.
- After snuffing out the candle, straighten the curled wick with a toothpick while the wax is soft. A candle with a straight wick burns better and lasts longer.
Further Reading:
Why a candle flame goes up, WonderQuest
Tips for taking care of candles: a burning guide, Island Candle Company
Candle burning, Newton ask a scientist
Q: When I was born, I had blond hair, but now it is dark brown. What caused this change? Eric, Farmington, Missouri, USA
A: "Light hair, as a rule, has a tendency to darken during childhood, says geneticist Rick Sturm, principal research fellow at the University of Queensland in Australia.
Hair darkens because genes that control hair colour switch on.
The more pigment produced in the hair follicle, the darker the hair. Much pigment results in dark brown hair; little pigment causes blond hair.
Some time during your childhood, the genes* controlling hair colour changed, and told the pigment protein to produce much pigment. Your hair consequently gradually turned to dark brown. It's an 'on' / 'off' order, like switching on a light.
We don't, however, have a clue why the genes changed. They just do for many children.
We strongly suspect genes control the timing of the change. In 1975, two pediatricians (Adam P. Matheny Jr. and Anne Brown Dolan of the University of Louisville School of Medicine) examined the hair colour of identical twins (169 female twins and 161 male) routinely from the time the twins were six months old until they were six years old.
They found marked changes in the hair colour for both sexes. Moreover, they discovered a "high rate" of agreement at every age "in spite of the general change in hair colour." Both twins' hair colour changed, beginning at about the same age and continuing at nearly the same rate. They, therefore, concluded that genes influenced the timing of colour changes.
In addition to hair darkening during childhood, "there are changes [causing hair to darken]also apparent at puberty that would likely be hormone related," says Sturm. The darkening can continue past puberty into the 30's and 40's.
By the way, the hair of some herd animals (for example, giraffes) darkens, but not with age. "The top male's hair darkens when he takes the alpha position," says Sturm, who suspects hormonal changes (maybe testosterone). "The specific example I have seen was a group of giraffes where the alpha male had noticeably darker spots. The keepers told me that this changed over time as the alpha male position was handed on. And it happens in other animals." -------- *Genes controlling hair colour include: tyrosinase,TYRP1, MATP, SLC24A5, SILV etcS and OCA2
Further Reading:
Sex and genetic differences in hair color changes during early childhood, (University of Louisville School of Medicine, 1975.
Hair color, Wikipedia
Understanding genetics, hair color, Stanford University
Readers' answers to question of the month (winning entry):
• Actually what makes a candle burn faster then others is the type of wick that you use. Sometimes pigment from dyes clog a wick, which can effect the burn time but, more often then not this is not the reason. Wicks are the burn time. -- Debi B., Ohio, USA
Next month's question:
Why do people only snore when they are asleep? You breathe all the time, but it's noisier when you are fast asleep. Why?
I'll publish the best answers, and you get credit. Click here: Answer-the-question to give me your answer.
April Holladay lives in Albuquerque, New Mexico. Her column, WonderQuest, appears every second Monday of the month on globetechnology.com. To read April's past columns, please visit her site. If you have a question for April, visit this information page.