My Understanding

When a candle is lit initially, it goes through a few stages (see, e.g. this explanation from the National Candle Association):

  1. Wick burns.
  2. Crusted wax on wick melts, evaporates and burns.
  3. Base of wick warms, nearby wax melts.
  4. Capillary action "pulls" melted wax near base of wick up through the wick to where it evaporates and burns.

If I extinguish the candle, then the wax solidifies.

My Question

Suppose I lit a candle briefly, then extinguished it right away. The wick would burn some of the wax that was in it, but wouldn't have time to pull max up it to replenish the wax that got burned.

Suppose I did this repeatedly. Eventually the candle wouldn't light as well, right?

For standard household candles, what's a minimum amount of time to let the candle burn before extinguishing it so that it replenishes its wax supply and doesn't burn too much of the wick off? A few seconds? A few dozen seconds? A minute or two? How do you know -- that is, how did you estimate this time scale?

If that's too broad, then what factors affect this time scale?

  • 1
    $\begingroup$ Test it and tell us... $\endgroup$ – user108787 Jun 7 '16 at 18:30
  • 1
    $\begingroup$ I'm a theorist. ;-) $\endgroup$ – jvriesem Jun 7 '16 at 18:33
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    $\begingroup$ How many theorists does it take to light a candle? Apparently an infinite number. Best of luck with it anyway $\endgroup$ – user108787 Jun 7 '16 at 18:36
  • $\begingroup$ Interesting problem. Have you attempted to solve it? If so, please could you post your attempt, or at least your thoughts on how to solve it. Seems to me a complicated problem. I agree with @count_to_10 that it is far easier (and more reliable) to do an experiment. $\endgroup$ – sammy gerbil Jun 7 '16 at 19:00
  • $\begingroup$ By what mechanism is the wax pulled up on the wick, capillary action i suppose? Then it must not be difficult to obtain an estimate. A quick search led me to Washburn's equation. $\endgroup$ – nluigi Jun 7 '16 at 20:41

Factors affect the time (i.e. from start to the time of equilibrium state where the following processes are sustainable: flame heat up wax, liquefied wax being pulled up, evaporated, wax vapor mixes with air, burn and produce heat) are followings, - size of wick (the larger, the more heat it can produce) - size of wick (for capillary flow) - wax type (melting temperature, surface tension etc.) - environment temperature (hot or cold) - environment oxygen concentration

You didn't quantify how much is to too much for burning out wick. So the constraint is not well defined. If we know these, a detailed calculation can be laid out for estimating this time.


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