Calling all pro/amateur fire investigators
November 4, 2010 12:04 PM   Subscribe

What caused this strange candle behavior?

On Tuesday night I was burning the four tea-lights that came with this product from Pier 1 Imports.

It was the second time I had lit these candles since I purchased the product. After about an hour of burning, one of the flames started burning very high (approximately 12 to 18 inches ABOVE the top of the candle holder). I checked to see if anything else had been lit (like the exterior decoration on the holder, or anything but the candle) but it seemed to be entirely localized inside the candle holder (and directly above it). The other 3 were burning/behaving normally. I blew out the other 3 and attempted to blow out the crazy tall flame. It would not blow out.

The flame was just getting bigger and so I ran to the kitchen to get a cup of water to extinguish the flame. When I poured the water on the flame, the flame exploded up at my face (it looked like a wall of flame from my point of view), and it singed my eyebrows/hair/eyelashes. My skin wasn't burned (thank gods).

I'd love to skip the responses of "it's impossible to know exactly what happened without witnessing it and/or lab tests..." because we both know that's true. But just hypothetically - what the hell happened here? Both in Phase A (the extremely tall flame) and Phase B (the "explosion")?

PS - I've since acquired multiple single-use fire extinguishers and a candle snuffer and plan to always take the "never leave a candle unattended" warning seriously.
posted by citywolf to Science & Nature (11 answers total) 3 users marked this as a favorite
The substance that's actually burning in a candle is a gas: wax vaporized by the heat of the flame. As to the explosion, my guess is that there was an excess of vaporized wax present when you doused the candle, and when the water hit it, it "splashed" upwards and ignited.
posted by mr_roboto at 12:18 PM on November 4, 2010

The size of a candle flame is related to the amount of wick that protrudes from the top of the candle; you may have had a candle with a wick that was accidentally made too large. As for the explosion that resulted from pouring water on the flame, remember that melted candle wax floats on water, and when the wax spreads out you can get a larger fire. Never pour water on a candle; a candle snuffer will work very nicely.

I could also design a candle to do the things that you describe in a more aggressive manner; make the wick out of magnesium tape, and it would burn with insane fury and would only burn all the more if you added water. However, you wouldn't have that kind of candle unless terrorists have infiltrated the candle factory, which seems unlikely.
posted by grizzled at 12:19 PM on November 4, 2010

The flame exploded in your face because you poured water into melted wax. The wax is hotter than the boiling point of water, and also less dense than the water. So, some of the water sank in to the hot wax, heated up, turned rapidly to steam, resulting in a steam explosion which spattered you with wax, but fortunately the wax wasn't burning.

It's basically a grease fire. You don't want to throw water on those either.

As for the reason for the flareup in the first place. Probably the wick was too long. Initially there wasn't enough liquid wax to matter, but once things got going, the long wick provided more fuel than a proper length wick, which released more heat, which melted more wax, which provided more fuel and exposed even more wick...
posted by Good Brain at 12:20 PM on November 4, 2010 [6 favorites]

Ok, scratch what I said about you being fortunate the wax wasn't burning, it may have been, to some extent, but you got off way better than you would have with an oil fire where the fuel is easier to ignite.
posted by Good Brain at 12:22 PM on November 4, 2010

I have no idea. mr_roboto's suggestion seems plausible.

Was the flame burning any particular color? (To rule out that candle being contaminated with some foreign substance.)

You should write Pier 1 a letter about it. One, because there might be something really screwed up about the candle set and they may need to pull the item from the shelves/print a warning and two, because they'll probably send you a gift certificate/free stuff.
posted by phunniemee at 12:22 PM on November 4, 2010

>You should write Pier 1 a letter about it. One, because there might be something really screwed up about the candle

Better yet, SEND them the candle (whatever remains of it), so that they can look at it & try to figure out if there is a dangerous defect. And for future reference (speaking as a person who has had a few screwups with burning wax), fire can also be smothered by reducing oxygen. My last wax fire was started when someone had left a candle on a plate on a burner, & then the burner got turned on. Upending a metal pot over the mess was sufficient to put it out. Not really ideal, but something to remember in an emergency.
posted by Ys at 12:44 PM on November 4, 2010

I had a candle burn hot enough to heat up its glass container to the point that the wax boiled over the sides. This is why, even if you are scrupulously careful with candles, even if you have no pets or children or other disrupters in the house, even if you are using proper candle holders, you must never leave a candle burning unattended.
posted by MrMoonPie at 1:07 PM on November 4, 2010

A friend had some tea lights in a holder like this and experienced the same "huge flame just getting bigger" issue. The problem there should be clear -- candles lower in the stack heated the candles higher up, melting and eventually boiling/vaporizing the wax in the upper candles. Result: column of flame.

Happily, he had a metal snuffer handy, so there was no part B.

I've never seen this happen because of an excessively long wick, but that does seem like the most likely explanation.
posted by hades at 2:01 PM on November 4, 2010

The explosion is almost certainly down to what Good Brain said. The big flame... man, 12 - 18 inches seems way too big to be accounted for purely by excessive wick length. I would tell Pier 1 about this. There may be something in the wax that shouldn't be there.
posted by Decani at 2:04 PM on November 4, 2010

Just to re-emphasize what others have said, the liquid wax in the glass reached its boiling point in that one candle. That was the critical event.

At the boiling point, the flame was no longer dependent on the wick, which normally carries wax from a pool of liquid, but not boiling, wax up to a zone where its hot enough to vaporize the wax, and the vaporized wax then feeds an established flame.
posted by jamjam at 2:15 PM on November 4, 2010

Thanks for sciencing this for me, MeFi. <3
posted by citywolf at 12:18 PM on November 5, 2010

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