It does not seem possible that the liquid remains from a burning candle can equate to the wax that once was. (esp. dripless type)
Where does it go? If some evaporates, does one find waxy build-up somewhere when it condenses? Any ideas?
I’d rather have a bottle in front of me than a frontal lobotomy - Hawkeye 4077th
Referring to Manhattan’s reference…
Can someone comfirm Cecil’s answer? This does not seem correct. The wax inhibits the flame from consuming the wick in seconds such that a candle can burn for hours.
The capillary action is hardly believable when the wick is 99% surrounded by solid wax.
I can’t see how the capillary action would have a chance to get established.
{Aside: Water and CO are always bi-products of combustion…no matter how “clean” one claims the fuel will burn.}
{Moderator may wish to move this from “General Questions” to “Comments on Cecil’s…”}
The scary thing is that 90% of the people think they’re above average! - unknown
I hope everyone will forgive my heresy, but as usual, How Stuff Works does a better job than Cecil at explaining the mysteries of our world’s physical phenomena.
~ Complacency is far more dangerous than outrage ~
My hypothesis, FWIW:
The wick in a candle is saturated with wax. Same as the wick in an oil lamp. The wax in the immediate vicinity of the flame (as well as the wax in the wick itself) is melted by the flame (remember that wax has a very low melting point), and that liquid wax is what’s burning. If you look at the top of a candle, there’s a little puddle of liquid wax right around the wick, and it’s this liquid wax that’s fueling the flame.
IIRC, wax doesn’t burn all that easily, so you need the wick to move things along. (WAG: I imagine that’s why it came into use in the first place, as a wax taper is less likely to be consumed by flames than a kerosene or oil lamp.)
Well, that’s my theory. Any takers?
*Jinx: Referring to Manhattan’s reference…
Can someone comfirm Cecil’s answer? This does not seem correct. The wax inhibits the flame from consuming the wick in seconds such that a candle can burn for hours.
The capillary action is hardly believable when the wick is 99% surrounded by solid wax.
I can’t see how the capillary action would have a chance to get established.*
Why is this unbelievable? Initially, the wick is saturated with wax. After being lit and charring the wick, the flame immediately melts wax closest to the wick and begins drawing it up by capillary action. When the flame is snuffed, enough wax is in the wick to initiate the process at the next lighting.
The wick is protected because the ignition point of the wick is higher that for wax. (This is also why you can boil water over a flame with a paper cup. The boiling water is only 212[sup]o[/sup], while the ignition point for the cup is 451[sup]o[/sup].) The drawn wax only goes a certain distance up the wick before it’s burned off. The unprotected wick then burns off.
With a oil lamp (ala Little House on the Prarie), the liquid fuel protects the wide fabric wick. But since the wick is pinched off, the flame can’t go down the wick any further. But with wax candles, the flame is allowed to burn as much wick as possible. Hence why oil lamp wicks last longer.
You’ll notice if you tilt a candle so that all the melted wax runs off the side instead of pooling that the wick begins to burn away quicker and ends up shorter. That’s because not enough wax is drawn to protect the wick, so it burns away.
{Aside: Water and CO are always bi-products of combustion…no matter how “clean” one claims the fuel will burn.}
It’s water (H[SUB]2[/SUB]0) and carbon dioxide (CO[sub]2[/sub]) (not carbon monoxide [CO]) as combustion products that define a clean burn. Unclean burns are what produce CO, sulfer oxides, and whatever else might be made from the fuel being used. Candles being mostly hydrocarbons, they don’t have many waste products other than water and carbon dioxide. (Some CO is made, as well as by-products of any perfumes in it.)
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A reply to AWB II:
Still thinking about the wax issue, but…
In studying combustion, you will find that the presence of CO as a bi-product is an indication of ineffecient burning. The more CO present, the less efficiently a flame is burning. This does factor into a “clean” burn.
There is an “ideal” equation for combustion in which CO is not a bi-product. Of course, the ideal world is hypothetical. The natural gas industry ran TV ads implying that burning natural gas does not yield CO. While gas might burn highly efficiently, CO is always a bi-product in the real world…along with others, like CO2, which I did not touch upon.
The scary thing is that 90% of the people think they’re above average! - unknown
It lands on your face and hair, and, through ciliary movement, is transported to your ear hole. Every time a candle is sold, the Q-Tip guys think, “ cha-ching !”
Everyone seems to be ignoring a key point (mentioned in the How Stuff Works link): Solid wax doesn’t burn. Neither does the liquid. What’s burning is the vapor.
The flame melts the wax. The wax wicks up the wick to the flame. The closer it gets to the flame, the hotter it gets. At a certain point, it turned to gas. That’s what’s burning.
Simple Gedanken proof: if the liquid wax were flammable, the flame would immediately spread to the puddle of liquid.
Your match is enough to melt the dried wax on the wick and turn it to liquid, then to gas.
“East is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does.” – Marx
Read “Sundials” in the new issue of Aboriginal Science Fiction. www.sff.net/people/rothman
I think RealityChuck’s right about the vapor. I once saw the liquid wax puddle “ignite”; on closer inspection, however, I saw that the flame was dancing on the surface of the puddle, and the puddle itself wasn’t actually burning. So it must have been the vapor burning. I missed that detail in my earlier explanation.
BTW, Jinx is right about CO and CO2 (I don’t remember how to do subscripts, sorry). CO2 is the “preferred” byproduct; CO is toxic and kills you quickly, whereas CO2 is commonly found in nature anyway, and plants use it. Of course, it is also a greenhouse gas (so you might say it kills you slowly), but that discussion belongs in Great Debates.
It never ceases to amuse me how people will quibble with Cecil’s masterful, simplified so-the-complete-idiot-can-understand-it explanation of a simple mechanism like a candle flame. Or question his physics.
The Straight Dope motto should be “Casting pearls before swine since 1973.”