Out of Control Candle

[K^2]

For paraffin to cause the water to flash into steam, you need paraffin at high temperature. Way higher than 100 °C.

Not really. You don't need all of the water to boil. A tiny amount is enough. Paraffin has pretty high heat capacity. It still needs to be well above 100°C, but for a larger candle, that's pretty typical.

Besides, it's a trivial experiment. Just make sure you are in flame-safe area, have eye protection, and a wet towel handy. Basically, your typical working with flammables setup. If I can find a suitable candle, I can make a video.

[lajoswinkler]

Grab a thermometer and measure the temperature of the molten pool.

I used to drop water with a pipette into it as a kid. Never ever even a sizzle. A candle simply can not heat itself up like that.

BTW, OP should draw or take a photo of the thing in question.

[MinimumSky5]

But remember, we've established that the candle probably had some sort of accelerant in the wax, and the flame was much bigger than normal before the water went in, so it is perfectly possible in those circumstances to get the wax over 100 degrees C.

[lajoswinkler]

No, we're testing the idea that it's a regular paraffin wax. Changing the variables ruins the experiment. We need a photo of the setup or else nothing matters.

What I'm telling you is that, if it's a regular wax, you need some pretty extraordinary conditions, like a burner/heater under the wax.

[K^2]

A candle simply can not heat itself up like that.

That's a silly statement. Candle can, in theory, get up to the temperature of the flame, which is more than hot enough. Paraffin is actually a very good insulator. (k = 0.25 W/(m K) !!!) The convection in the molten pool is going to be almost zero, since it's heated from above. Really, the only limiting factor is the size of the candle. An experiment you might have done with 1/2" - 1" candle would be completely different from something in 3" -4" diameter. Add a glass or worse, ceramic container around it, and that thing will heat up even more.

So, say you have 0.5cm deep pool of wax. Lets say, surface is at 100° and point of contact is at 50°C, which is somewhere in the range of melting points for a typical candle. That's just 2.5kW/m². Even looking at a pool 10cm in diameter, that's just 20W. For comparison, output of a tiny tea candle is closer to 30-40W. Larger candle will pump 50W into wax alone, quite easily, which should allow wax to heat up to 150°C or more.

[lajoswinkler]

Then please explain the fact I've never experienced anything like this when I used to drop water by pipette into molten pool of wax in all kinds of candles just for fun? Surely there's a much greater chance of water going nuts if it's just a small drop and not a stream from the faucet, because its temperature will quickly change due to its tiny size.

Also explain the fact that OP could grab the container without problems. It wasn't made out of asbestos.

[K^2]

You are using anecdotal evidence to make general claim. I'm giving you numbers. I don't know what special conditions you were trying to do this in. I'm telling you conditions under which it should work, and under which I've seen water flash-boil in candles.

One of the things which could make a difference between drops and splashing water in is the vapor shield. Your experiments would allow for minimal heat transfer from wax to water. Splashing water in would disturb surfaces of both water and wax ensuring maximum heat transfer.

[MinimumSky5]

Also, we're overlooking the fact that the water was from a facet, not being gently placed into the container. If the water was under just a small amount of pressure, that alone could make the wax splash upwards, regardless of temperature.

[lajoswinkler]

You are using anecdotal evidence to make general claim. I'm giving you numbers. I don't know what special conditions you were trying to do this in. I'm telling you conditions under which it should work, and under which I've seen water flash-boil in candles.

One of the things which could make a difference between drops and splashing water in is the vapor shield. Your experiments would allow for minimal heat transfer from wax to water. Splashing water in would disturb surfaces of both water and wax ensuring maximum heat transfer.

No, I'm doing the opposite. I'm using the empirical data I have to make a hypothetical explanation. I actually did these experiments. All you did was use a very crude, half baked approximation and then pump out an explanation.

How on earth did you come up with pumping 50 W into the wax, is beyond my understanding.

[Beowolf]

Most recent EPA studies on fracking have declared it 'safe', although there is still a large group/political agenda which insists it isn't.

Are my personal friends in NW Pennsylvania who can set their water on fire members of a large group or a political agenda? If industry poisons a large group's drinking water, shouldn't that count as a problem?

The explanation they've been given so far wasn't particularly useful: Fracking is safe. Your problem was because we accidentally spilled tons of the stuff on the ground and didn't even try to clean it up. Oh, and since it's a trade secret, we don't have to tell you or the government what was in there. And since you don't know what's in it, you can't prove it's harmful so have no legal standing to sue us.

Not that comforting. Some parts of living in a declining corrupt empire suck.

[WinkAllKerb'']

Some parts of living in a declining corrupt empire suck.

Some parts of living in a declining corrupt empire suck.

Some parts of living in a declining corrupt empire suck.

beetlejuice, beetlejuice, beetlejuice ; )

[MinimumSky5]

Well, it is right to say that franking in and of itself is safe, in the same way the drilling for oil is safe, but when mistakes are made, it becomes very unsafe.

[Wesreidau]

THATS IT.

I'm going to burn my eyebrows off after work today, but there will be !!SCIENCE!!

The community has three hours to assemble a zero-budget experiment. I will be using a dead muddy patch of a soybean field as my test ground.

All documentation shall be provided in writing. No photographs.

[Wesreidau]

One candle (3 inch by 3 inch cylindrical glass scented candle, Glade, Made in Canada) with modified wick (scrap of paper towel) producing flame of four inches for two minutes was splashed with drops of lukewarm water from a height of one meter. Audible hissing and popping sounds accompanied by flame expanding dramatically within confines of glass container.

Theory of oil-water conflagration in low-temperature candle wax supported.

It is the opinion of this tester that the a larger well of molten wax and the standard aerator of a bathroom faucet is responsible for the OP's more dramatic result. A column of aerated tapwater contains a large fraction of air bubbles and 'foams' the water, allowing smaller amounts of water to come in contact with molten wax and vaporize against it. Additionally the candle's label specifically directs the user not to extinguish it with water.

In other news, kerosene doesn't have to melt steel beams, steel burns merrily enough on its own.

- - - Updated - - -

The convection in the molten pool is going to be almost zero, since it's heated from above.

I have noticed distinct 'thermal' currents in a large enough pool of molten wax under a candle as the heated wax spreads out on the surface and draws cooler wax up from below. A bit counter-intuitive, but drop some glitter in and watch.

[Frybert]

Additionally the candle's label specifically directs the user not to extinguish it with water.

The next time you see a warning label and think to yourself 'why do they need this', remember this thread.

[Wesreidau]

AFK drying my towels in a microwave.

[Skyler4856]

This was EXACTLY my first thought. I am pretty sure this is what happened.

When we were told this in school, they never really properly drove home the message.

[Tahlia]

I tried putting paper in my candle pot (bad idea). The flame got bigger and bigger and bigger and I put one drop of water on it and it erupted with an even bigger flame! I called my parents in. How could I have extinguished the flame myself?

[Nightside]

7 hours ago, Tahlia said:

I tried putting paper in my candle pot (bad idea). The flame got bigger and bigger and bigger and I put one drop of water on it and it erupted with an even bigger flame! I called my parents in. How could I have extinguished the flame myself?

Put a lid on it.

[sevenperforce]

22 minutes ago, Nightside said:

Put a lid on it.

applicable for a necro like this

[Nuke]

i love the violent reaction you get when you fail to dry your potatoes before tossing them into the deep frier. a fine example of why you should never rush the cook. there is a way to get rid of hot oil without lighting your house on fire though. turn the faucet on cold perhaps a quarter its max flow rate. allow it to flow gently down the side of the sink towards the drain with laminar flow (avoid splashes), then slowly pour your oil directly into the drain. its important that your oil to water ratio be at least 3x more water than oil, as you need enough thermal mass to avoid a rapid boil off. you should never pour water into hot oil because that is a good way to build and impromptu flame thrower. i dont like leaving it out because the cats have a way of checking out the kitchen while everyone else is eating, and leaving it out to cool can cause kitty some nasty burns. i suppose you could just cover it but that's wasting dishes, which would not be an issue if the freeloaders i feed would do dishes. 

 

oh damn necro.

Edited April 12, 2020 by Nuke

[RCgothic]

On 4/9/2020 at 4:45 PM, Tahlia said:

I tried putting paper in my candle pot (bad idea). The flame got bigger and bigger and bigger and I put one drop of water on it and it erupted with an even bigger flame! I called my parents in. How could I have extinguished the flame myself?

The three pillars of a fire are fuel, air, and ignition (heat). Removing any one puts out the fire.

The safest way to extinguish a candle is with a candle snuffer. It's bell-shaped with a handle and you place it over the top of the candle. Because the exhaust products (containing no oxygen) are hot they rise, displacing oxygen containing air down and out of the bell. When the level of air falls below the level of the wick the candle goes out.

If your candle is in a glass container, you can also snuff it by placing something flame-proof over the top. When all the air is used up the candle will go out.

A carbon dioxide or nitrogen fire extinguisher work both by excluding air, and also by removing heat because expanding gases are cold.

Blowing on a candle removes the heat (not the oxygen!) which puts a fire out.

You can also extinguish small candles with your fingers. Lightly wet your fingers (not so much they drop) and firmly pinch the wick between thumb and forefinger, then release. This both excludes air and cools the wick. Water (or saliva which is mostly water) has a high specific heat so it doesn't heat up quickly. The high thermal inertia of your damp fingers relative to the wick and brief contact mean this can be done without getting burned.

 

In the incident you describe, you effectively added extra wick with the paper, which allows more fuel to burn at once. I really wouldn't recommend doing that again! You do not want to blow on it and send burning paper everywhere.

If the paper doesn't burn off quickly by itself and you can't easily snuff it, I'd remove the paper with tweezers or pliers and quench in a basin of water. If I didn't have tweezers, I'd damp my fingers (no drops!) and quickly remove and quench the paper that way (as a fairly last resort - you'd have to be sure doing nothing is unsafe). The candle should then be back under control and be extinguished normally.

 

This is an old thread, but I can see how you'd have found it in a Google search and it's always appropriate to dispense safety advice.

Edited April 12, 2020 by RCgothic