7) The candle wick is probably the best re-invention of the 19th century.

Burn baby, burn.

Burn baby, burn.

Candles have been around for many thousands of years, varying in their aesthetic and chemical design. The most chronologically recent technological change to the candle happened in the late 19th century, and was in regards to the wick. The wick of the candle is arguably the most important component. The wax (or substitute material) is simply the fuel. The wick regulates burn time, the size of flame, amount of fuel consumed, the amount of heat and light generated, and maintains the overall consistency to the burn.

Prior to 1900 the wick was simply twisted strands of cotton sometimes with a lead core to help stability. The first change on heath and safety grounds was the switch from lead to zinc for fears of lead poisoning. This no doubt improved the quality of the living environment in regards to health, however there was still a fundamental problem with the candle; it was majorly unreliable. As the only source of light it needed to be consistent, and so a new braided wick was introduced.

As the fuel to a candle is the wax, this is what is burning to produce the light and heat, not the wick. The wick is simply a delivery devise for the wax. As the base of the flame burns it melts the top layer of the candle (light blue flame). This wax in its molten form then travels up the wick via capillary action to the heart of the flame and burns off (golden yellow flame). The tip of the flame (dark orange) is the area where the remaining carbon in the wax if being oxidized.

With this in mind, as the candle reduced in size and the wax was being burnt away, the cotton wick grew increasingly longer. This severely affected the quality of the flame, the amount of light being emitted and it would begin to smoulder forming acrid black smoke. To prevent this, a special clipper called a snuffer was used to trim down the wick. This needed to be preformed on a very regular basis to maintain consistency to the burn. Incidentally, the action of snuffing the candle often unintentionally extinguished the flame which gave rise to the usage of the word today.

The braided wick changed this as it was self-consuming and eradicated the need for a snuffer. The braided wick was intertwined with equal strands (as in hair braiding) on a flat surface. This allowed the wick to form a controlled bend under extreme heat. As the candle burns away the wick slowly curls until it has effectively doubled back on itself within the flame. The edge of the flame then burns off the wick regulating its length automatically for the life of the candle.

NB. An interesting side note is that however genius the wick design is, the biggest problem a candle has is its inefficiency in fuel consumption. This is not a major problem and doesn’t really need to be addressed due to the low production costs of a candle. However, it is a neat little trick that never ceases to entertain me. To maintain a decent flame size, the length and girth of the wick is therefore dictated. The upshot of having a wick with these ratioed dimensions is that it doesn’t give the flame long enough to burn all of the liquid wax that it has been given. Therefore liquid particles of wax are vaporised. There are two ways to detect this:
1) Hold a silver spoon several centimetres over the flame for a few seconds. You will notice a black residue forming. This is a mixture of vaporised wax and carbon.
2) A more fun way is to blow out the candle gently. Then with a lit match, quickly touch the ‘smoke’ emitted from the extinguished candle. You will see the flame jump from the match and seemingly travel through the air and land on the wick, relighting the candle. This is because the match is reigniting the vaporised wax particles which trail though the air all the way back to the wick. Sad, but kinda cool!

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April 2009

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