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The Daily Fix: De-Ice a Frozen Lock

Filed Under: Essential Skills, Know-How, Outdoors

It's late. It's dark. You trudge through the snow to your car and discover the locks are all iced up. Don't panic! There's a clever way to solve this problem. Just apply a glob of hand sanitizer to the key and wiggle it gently into the lock.

Why does this work? Hand sanitizer's primary ingredient is alcohol, which melts ice clear away in seconds.

I love this tip, especially since I usually keep a travel-size bottle of Purell in my bag anyway. Another plus: hand sanitizer is much easier to come by in a pinch than specialty de-icing products. After all, even if you aren't carrying any Purell yourself, you can probably borrow some from a friend or passerby, right?

A few more clever de-icing ideas:

Use a cigarette lighter to heat the tip of the key. It may take a few attempts, but the hot key should gradually melt the ice.

Spray a little WD-40 into the lock. Just remember WD-40 is highly flammable. If it doesn't work, don't try the cigarette lighter method afterwards -- at least not on the same lock!

If your car is parked at home you can also try breaking out the hair dryer. A blast of hot air should be all that's needed to get that lock finally de-iced. If you don't have a suitably long extension cord, try pouring some very hot water over the lock. Hopefully you'll be on your way in no time!

More cool ideas:
Top 10 DIY Car Hacks
All About Locks

  • Rick

    WD40 is the last product you want to use. While an excellent product it leaves a film wax on the interior which just thicken up and makes the lock components even tighter. For preventive purposes use a lock deicer which uses alcohol to melt the ice crystals and leaves a film of oil instead. In a pinch a key in the lock heated with a lighter works as well, just be careful about any plastic grip on the key inself. Spray your door gaskets with silicone spray in th late fall and they'll NEVER freeze shut!

  • Jamie

    Do not, repeat DO NOT pour VERY HOT WATER on your door to melt ice. #1: You stand a very good chance of having it freeze right back over (hot water freezes faster than cold) and you will SEAL your door lock. #2: A rapid temperature change will/can cause your car paint to craze, crack, separate from the paint substrates...causing paint failure in the future. #3: Should you be a "pour-shot" and include your glass with the deluge you will cause it to shatter. Best bet...Purell, hot key, better yet: some HOUDINI lock lube as advance preparation of the cold. After living/skiing in Europe you get wise to this and move to South Carolina or Florida.

  • gb

    Hot water does NOT freeze faster than cold water.. Water has to get cold in order to freeze and it gets that way faster if it starts out cold.

  • Clarence

    Hot water does NOT freeze faster than cold. Total myth. Ihave a degree in thermodynamics !!

  • Susan Denley

    DO NOT USE A HAIR DRYER! You can be electrocuted so easily with a hair dryer!


    True, electicity is always bad when combined with a good conductor such as water. However; modern hair dryers have a built in GFCI circuit which, if operating properly, should prevent electocution. But why hassle with a hair dryer outside?

  • Steve DeFrank

    Applying heat to the key if a late model key can damage the electronics in the key, just saw that on motorweek.

  • robert

    how about a bottle water in the microwave until really warm and pour it on the corner of the window where the lock is, and the crack between the two doors.

  • PhysicsPolice

    In reply to "gb" who said that hot water does not freeze faster than cold water.............OH YES IT DOES..........

    Monwhea Jeng (Momo),
    Department of Physics, University of California

    Can hot water freeze faster than cold water?

    Yes -- a general explanation
    History of the Mpemba Effect
    More-detailed explanations

    Yes -- a general explanation

    Hot water can in fact freeze faster than cold water for a wide range of experimental conditions. This phenomenon is extremely counter- intuitive, and surprising even to most scientists, but it is in fact real. It has been seen and studied in numerous experiments. While this phenomenon has been known for centuries, and was described by Aristotle, Bacon, and Descartes [1-3], it was not introduced to the modern scientific community until 1969, by a Tanzanian high school student named Mpemba. Both the early scientific history of this effect, and the story of Mpemba's rediscovery of it, are interesting in their own right -- Mpemba's story in particular provides a dramatic parable against making snap judgements about what is impossible. This is described separately below.

    The phenomenon that hot water may freeze faster than cold is often called the Mpemba effect. Because, no doubt, most readers are extremely skeptical at this point, we should begin by stating precisely what we mean by the Mpemba effect. We start with two containers of water, which are identical in shape, and which hold identical amounts of water. The only difference between the two is that the water in one is at a higher (uniform) temperature than the water in the other. Now we cool both containers, using the exact same cooling process for each container. Under some conditions the initially warmer water will freeze first. If this occurs, we have seen the Mpemba effect. Of course, the initially warmer water will not freeze before the initially cooler water for all initial conditions. If the hot water starts at 99.9°C, and the cold water at 0.01°C, then clearly under those circumstances, the initially cooler water will freeze first. However, under some conditions the initially warmer water will freeze first -- if that happens, you have seen the Mpemba effect. But you will not see the Mpemba effect for just any initial temperatures, container shapes, or cooling conditions.

    This seems impossible, right? Many sharp readers may have already come up with a common proof that the Mpemba effect is impossible. The proof usually goes something like this. Say that the initially cooler water starts at 30°C and takes 10 minutes to freeze, while the initially warmer water starts out at 70°C. Now the initially warmer water has to spend some time cooling to get to get down to 30°C, and after that, it's going to take 10 more minutes to freeze. So since the initially warmer water has to do everything that the initially cooler water has to do, plus a little more, it will take at least a little longer, right? What can be wrong with this proof?

    What's wrong with this proof is that it implicitly assumes that the water is characterized solely by a single number -- the average temperature. But if other factors besides the average temperature are important, then when the initially warmer water has cooled to an average temperature of 30°C, it may look very different than the initially cooler water (at a uniform 30°C) did at the start. Why? Because the water may have changed when it cooled down from a uniform 70°C to an average 30°C. It could have less mass, less dissolved gas, or convection currents producing a non-uniform temperature distribution. Or it could have changed the environment around the container in the refrigerator. All four of these changes are conceivably important, and each will be considered separately below. So the impossibility proof given above doesn't work. And in fact the Mpemba effect has been observed in a number of controlled experiments [5,7-14]

    It is still not known exactly why this happens. A number of possible explanations for the effect have been proposed, but so far the experiments do not show clearly which, if any, of the proposed mechanisms is the most important one. While you will often hear confident claims that X is the cause of the Mpemba effect, such claims are usually based on guesswork, or on looking at the evidence in only a few papers and ignoring the rest. Of course, there is nothing wrong with informed theoretical guesswork or being selective in which experimental results you trust -- the problem is that different people make different claims as to what X is.

    Why hasn't modern science answered this seemingly simple question about cooling water? The main problem is that the time it takes water to freeze is highly sensitive to a number of details in the experimental set- up, such as the shape and size of the container, the shape and size of the refrigeration unit, the gas and impurity content of the water, how the time of freezing is defined, and so on. Because of this sensitivity, while experiments have generally agreed that the Mpemba effect occurs, they disagree over the conditions under which it occurs, and thus about why it occurs. As Firth [7] wrote "There is a wealth of experimental variation in the problem so that any laboratory undertaking such investigations is guaranteed different results from all others."

    So with the limited number of experiments done, often under very different conditions, none of the proposed mechanisms can be confidently proclaimed as "the" mechanism. Above we described four ways in which the initially warmer water could have changed upon cooling to the initial temperature of the initially cooler water. What follows below is a short description of the four related mechanisms that have been suggested to explain the Mpemba effect. More ambitious readers can follow the links to more complete explanations of the mechanisms, as well as counter- arguments and experiments that the mechanisms cannot explain. It seems likely that there is no one mechanism that explains the Mpemba effect for all circumstances, but that different mechanisms are important under different conditions.

    1. Evaporation -- As the initially warmer water cools to the initial temperature of the initially cooler water, it may lose significant amounts of water to evaporation. The reduced mass will make it easier for the water to cool and freeze. Then the initially warmer water can freeze before the initially cooler water, but will make less ice. Theoretical calculations have shown that evaporation can explain the Mpemba effect if you assume that the water loses heat solely through evaporation [11]. This explanation is solid, intuitive, and evaporation is undoubtedly important in most situations. However, it is not the only mechanism. Evaporation cannot explain experiments that were done in closed containers, where no mass was lost to evaporation [12]. And many scientists have claimed that evaporation alone is insufficient to explain their results [5,9,12].
    2. Dissolved Gasses -- Hot water can hold less dissolved gas than cold water, and large amounts of gas escape upon boiling. So the initially warmer water may have less dissolved gas than the initially cooler water. It has been speculated that this changes the properties of the water in some way, perhaps making it easier to develop convection currents (and thus making it easier to cool), or decreasing the amount of heat required to freeze a unit mass of water, or changing the boiling point. There are some experiments that favor this explanation [10,14], but no supporting theoretical calculations.
    3. Convection -- As the water cools it will eventually develop convection currents and a non-uniform temperature distribution. At most temperatures, density decreases with increasing temperature, and so the surface of the water will be warmer than the bottom -- this has been called a "hot top." Now if the water loses heat primarily through the surface, then water with a "hot top" will lose heat faster than we would expect based on its average temperature. When the initially warmer water has cooled to an average temperature the same as the initial temperature of the initially cooler water, it will have a "hot top", and thus its rate of cooling will be faster than the rate of cooling of the initially cooler water at the same average temperature. Got all that? You might want to read this paragraph again, paying careful distinction to the difference between initial temperature, average temperature, and temperature. While experiments have seen the "hot top", and related convection currents, it is unknown whether convection can by itself explain the Mpemba effect.
    4. Surroundings -- A final difference between the cooling of the two containers relates not to the water itself, but to the surrounding environment. The initially warmer water may change the environment around it in some complex fashion, and thus affect the cooling process. For example, if the container is sitting on a layer of frost which conducts heat poorly, the hot water may melt that layer of frost, and thus establish a better cooling system in the long run. Obviously explanations like this are not very general, since most experiments are not done with containers sitting on layers of frost.

    Finally, supercooling may be important to the effect. Supercooling occurs when the water freezes not at 0°C, but at some lower temperature. One experiment [12] found that the initially hot water would supercool less than the initially cold water. This would mean that the initially warmer water might freeze first because it would freeze at a higher temperature than the initially cooler water. If true, this would not fully explain the Mpemba effect, because we would still need to explain why initially warmer water supercools less than initially cooler water.

    In short, hot water does freeze sooner than cold water under a wide range of circumstances. It is not impossible, and has been seen to occur in a number of experiments. However, despite claims often made by one source or another, there is no well-agreed explanation for how this phenomenon occurs. Different mechanisms have been proposed, but the experimental evidence is inconclusive. For those wishing to read more on the subject, Jearl Walker's article in Scientific American [13] is very readable and has suggestions on how to do home experiments on the Mpemba effect, while the articles by Auerbach [12] and Wojciechowski [14] are two of the more modern papers on the effect.

  • Noel

    Try 2 ice cube trays, one hot and one cold if you want to test the theory in your freezer, but use the hand sanitizer if you want to de-ice the car lock.

  • Storm

    lordy... lol... while i appreciate the research... doncha think a LINK woulda been sufficient?

  • Paul

    Is this one of them urine legends?

    We need those T.v. guys to settle this .. Myth Busters, or whatever they are called ..

  • Paul

    I thought the Mpemba Effect was how a 7-11 Slurpee at room temp disappears MUCH more slowly than a chilled one ..

  • PhysicsPolice

    Re: Storm's comment - Although I appreciate your appreciation, the info was aimed at the poster "gb" who didn't have enough sense to even use google before spouting off about hot water freezing faster than cold - without looking it up first...Considering the fact that the poster was already failing at utilizing any form of common sense - No, I don't the link would have been a sufficient way to make my point. That is why the body of the article was included.

    But, thanks "Storm" for letting us all know what YOU would have done IF it were YOU making a post in about the topic of freezing hot water.....but all in all, you contributed nothing to the Topic at hand.

    Suggestion: Focus on the topic, your own opinion and other posters have clearly done, without it having to be explained to them.

    So you, Storm, got a posting lesson and hopefully at least one person learned about hot/cold water freezing.

    Happy Posting !

  • colleen

    Okay so this article has been totally shot down by people who actually do know more than the writer. Just opt for the garage or stay home. :o)

  • Hotcake

    Another method...FYI...a torch lighter, just carefully heat the keyhole
    of your vehicle door lock...SHAZAM!...The ice is melted-door opens...The torch lighter can be purchased at any store in the outdoor
    Bar-B-Que grill section.

  • robert

    SE Texas, the snow is less than a day unlike the north. maybe a molotov cocktail might work.

  • robert

    Hey mr Riverside, I went to UCR on a field trip in 1981.

  • T'sMama

    Do NOT use the lighter on the key method! Most new locks have plastic in them and it can melt the inside!
    HOT water DOES freeze's a fact! Just like starting with cold water boils faster than starting with hot!

  • T\\\'sMama

    Do NOT use the lighter on the key method! Most new locks have plastic in them and it can melt the inside! The key itself can have the electronics inside ruined!

    GB...HOT water DOES freeze's a fact! Just like starting with cold water boils faster than starting with hot!

    WD-40 leaves residue inside that can cause a problem later.

    The best thing is the hand sanitizer or the hair dryer. USE the hairdryer with caution and common sense so you don't get electrocuted!

    If you have a tow card, call a tow truck driver and let them de-ice it.

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