[IR] Candles

Well, again, this is not my usual post day, its a Sunday, not a Saturday, but, its my birthday today, so I thought I would write about something related to birthdays - candles. If you remember, my last post was way back in the 22nd of September and I said that it would probably be my last post before my termly reflection. Well you get a treat. So let's get right to the post.

So, how do candles work?
Candles really are an amazing lighting system -- the fuel itself is the package. There are two parts that work together in a candle:
The fuel, made of some sort of wax
The wick, made of some sort of absorbent twine


The wick needs to be naturally absorbent, like a towel, or it needs to have a strong capillary action. If you buy a length of un-waxed wick at a craft store and play with it, you will find that it feels like soft string and absorbs water very well. This absorbency is important in a candle because the wick needs to absorb liquid wax and move it upward while the candle is burning.


Paraffin wax is a heavy hydrocarbon that comes from crude oil. When you light a candle, you melt the wax in and near the wick. The wick absorbs the liquid wax and pulls it upward. The heat of the flame vaporizes the wax, and it is the wax vapour that burns.

The reason the wick does not burn is because the vaporizing wax cools the exposed wick and protects it. You may have seen the camping trick of boiling water in a paper cup. The cup does not burn because the water inside cools it. The liquid wax does the same thing for the wick.

Paraffin wax will burn on its own, but it is like cooking oil, motor oil and coal in that you have to get it very hot for combustion to begin. An oil fire is intense and very hard to put out. Paraffin is the same way. In a candle, this works great -- only the tiny amount of wax on the wick is hot enough to vaporize and burn.