Why does a candle wick need to be bent to burn?

[Cecrle]

Hello all,

My chemistry teacher gave us a little extra credit assignment the other
day; it is to find out why a candle's wick needs to be bent for it to
burn.

He said that a candle wick pointing straight up would not burn. I think
it is either because the evaporating wax vapor doesn't have enough space
to react with oxygen and still stay near the wick *or* the end of the wick
needs to touch the edge of the flame to stay hot enough.

*SO: why does a wick need to be bent to burn?*

I'm really not sure, so if you know or have any ideas, please email me
with them!!!

Thanks,
-FC

[Michael Supp]

Cecrle wrote:

>
> *SO: why does a wick need to be bent to burn?*

It doesn't! Else how do you light one to begin with?

The wick bends because the closer you get to the end of the wick the
more burned (shortened) the wick fibers become. (I think!??)

Mike

[Joshua_Putnam]

In <504r6h$6...@netaxs.com> mral...@netaxs.com (Mark Albert) writes:

>Cecrle (mce...@sbt.infi.net) wrote:
>: Hello all,

>:
>: My chemistry teacher gave us a little extra credit assignment the other
>: day; it is to find out why a candle's wick needs to be bent for it to
>: burn.
>:
>: He said that a candle wick pointing straight up would not burn.

>It most certainly doesn't. It is, however, a very good question to get
>students to think like scientists. But a wick is going to be limited in
>its height above the liquid wax since ... ,

I think this may be a trickier trick question than it originally
appeared: the wick itself will not normally burn unless it is
bent over -- it just provides a path for the molten wax to wick
up and evaporate into the flame. When the wick bends, its tip
goes beyond the rising column of wax vapors and the wick itself
can burn. Otherwise the wick itself does not see enough oxygen
to burn because the wax is burning instead, using up the
available O2.

The wick will burn briefly when the candle is lit, and after the
candle is put out the wick can smolder a while after the air gets
to it directly.

Think of a kerosene lantern: if you keep your wick well trimmed
you get a cleanly-burning flame fueled only by kerosene. If
your wick gets scraggly, the tips of it char outside the
envelope of the center flame. The only times the wick itself
gets burned normally is briefly when lighting, briefly after
extinguishing, and sometimes quite badly if the lantern runs out
of kerosene.

--

Jo...@WolfeNet.com is Joshua Putnam / P.O. Box 13220 / Burton, WA 98013
"My other bike is a car."

[Martin Carr]

In article <5000e1$l...@nw101.infi.net>, Cecrle <mce...@sbt.infi.net>
writes

>Hello all,
>
>My chemistry teacher gave us a little extra credit assignment the other
>day; it is to find out why a candle's wick needs to be bent for it to
>burn.
>

>He said that a candle wick pointing straight up would not burn. I think
>it is either because the evaporating wax vapor doesn't have enough space
>to react with oxygen and still stay near the wick *or* the end of the wick
>needs to touch the edge of the flame to stay hot enough.
>

>*SO: why does a wick need to be bent to burn?*
>

>I'm really not sure, so if you know or have any ideas, please email me
>with them!!!
>
>
>Thanks,
>-FC
>

Greetings!

No-one told my candles this!

In fact the wick is not the thing which burns primarily, as an examination of
its charred (but functioning) remains will show. However, for convenience I
will refer to the wick as "burning". A wick could be made from ANY absorbent
material, try tissue paper - even fibre glass should work as a wick in an oil
lamp (no good in candles as it doesn't burn down with the candle).

The fuel is wax VAPOUR.

1 Heat is needed to melt wax,
2 Wax soaks up the wick by capillary action,
3 If sufficient heat is available the wax evaporates...
4 ...reacts with oxygen in the air (combustion) which...
5 ...produces excess heat to keep the process going.
6 The yellow flame itself is a convection current of incandescent (good word
that) cabon particle produced in the burning mixture of wax vapour and oxygen.

Bent wicks will burn BETTER due to offering a wider (horizontal) surface for
evaporation to take place, but that does not mean a straight wick cannot burn.
Try heating a straight wick from the side and low down - it WILL burn.

Additional - Try to observe convection currents in the molten wax around the
wick while the candle burns. This is sometimes evident from bit of charred
material floating about in the liquid wax. Take care not to burn yourself!

Hope this helps and gives you other ideas. In fact there is a lot of science
you can learn from studying candles.

Martin Carr

We fail to notice the simple everyday things about us - until they are there no
longer.

Turnpike evaluation. For Turnpike information, mailto:in...@turnpike.com

[Mark Albert]

Cecrle (mce...@sbt.infi.net) wrote:
: Hello all,

:
: My chemistry teacher gave us a little extra credit assignment the other
: day; it is to find out why a candle's wick needs to be bent for it to
: burn.
:
: He said that a candle wick pointing straight up would not burn. I think
: it is either because the evaporating wax vapor doesn't have enough space
: to react with oxygen and still stay near the wick *or* the end of the wick
: needs to touch the edge of the flame to stay hot enough.
:
: *SO: why does a wick need to be bent to burn?*
:
: I'm really not sure, so if you know or have any ideas, please email me
: with them!!!
:
:
: Thanks,
: -FC

:

It most certainly doesn't. It is, however, a very good question to get
students to think like scientists. But a wick is going to be limited in
its height above the liquid wax since ... ,

I'll let you finish the sentence.