Pat, I'm not saying that water coming out of a
cup isn't true. I'm saying that water exploding
far out of a c far enough to damage your eye is
rare. I have had water boil over from a cup.
earlier, Pat Ferguson, wrote:
>John,
>
>I have actually had water blow out of a cup in
>the microwave, or even on the counter, after
>I've taken it out of the microwave. I've had
>this happen with gravy, and there was some
>grease in the broth so it really made a mess.
>
>It does sound unbelieveable, but unless you have
>had it happen, it's hard to believe. I've had it happen several times.
>
>Pat Ferguson
>
>At 03:54 PM 8/30/2006, you wrote:
>>Phil, from snopes, true, but rare. I put in
>>for a search string, heating water in a
>>microwave. After clicking on a link, I snipped this:
>>
>>Origins: Exploding water? In a nutshell,
>>Too hot to handle
>> yes, water can "explode" in the fashion
>> described above. However, it takes near
>>perfect conditions to bring this about, thus
>>"exploding water" is not something the
>>average hot beverage drinker who would
>>otherwise now be eyeing his microwave with
>>trepidation need fear. Odds are, you'll go
>>through life without ever viewing this
>>phenomenon first-hand, and if you're one of the
>>rare few who does get to see it,
>>you will likely not be harmed by the experience
>>(that would take your standing right
>>over the cup at the instant it happened, and
>>the liquid's bolting up and hitting
>>your skin).
>> The Food and Drug Administration (FDA) has advised consumers:
>> This type of phenomenon occurs if water is
>> heated in a clean cup. If foreign materials
>>such as instant coffee or sugar are added
>>before heating, the risk is greatly reduced.
>>If superheating has occurred, a slight
>>disturbance or movement such as picking up
>>the cup, or pouring in a spoon full of instant
>>coffee, may result in a violent eruption
>>with the boiling water exploding out of the cup.
>> What Can Consumers Do to Avoid Super-Heated Water?
>> Follow the precautions and recommendations
>> found in the microwave oven instruction
>>manuals, specifically the heating time.
>> Do not use excessive amounts of time when
>> heating water or liquids in the microwave
>>oven.
>> Determine the best time setting to heat the
>> water just to the desired temperature
>>and use that time setting regularly.
>> The e-mailed warning quoted above a model of
>> non-specificity (no names, date, or
>>locale; only the detail that the "victim" was
>>26 years old, presumably to enforce
>>the idea that this accident could not be blamed
>>on a child's typical lack of caution),
>>leaving us able to address only its theoretical
>>aspects. Nearly every science writer
>>who has tackled the topic notes that the
>>"severe superheating" phenomenon is real
>>but likely not nearly as common as the message
>>cited above might make it sound.
>> In an article for New Scientist, Richard Barton wrote:
>> A portion of the water in the cup is becoming
>> superheated — the liquid temperature
>>is actually slightly above the boiling point,
>>where it would normally form a gas.
>>In this case, the boiling is hindered by a lack
>>of nucleation sites needed to form
>>the bubbles
>>. . .
>> I imagine that by keeping the cup still and
>> microwaving for a long time, one could
>>blow the entire contents of the cup into the
>>interior of the microwave as soon as
>>you introduced any nucleation sites. It is this
>>sometimes explosive rate of steam
>>production that means you should take great care when using a microwave oven.
>> From the
>>How Things Work
>> web site:
>> Glass containers are clearly the most likely
>> to superheat water because their surfaces
>>are essentially perfect. Glasses have the
>>characteristics of frozen liquids and a
>>glass surface is as smooth as... well, glass.
>>When you overheat water in a clean
>>glass measuring cup, your chances of
>>superheating it at least mildly are surprisingly
>>high. The spontaneous bubbling that occurs when
>>you add sugar, coffee powder, or
>>a tea bag to microwave-heated water is the
>>result of such mild superheating. Fortunately,
>>severe superheating is much less common because
>>defects, dirt, or other impurities
>>usually help the water boil before it becomes
>>truly dangerous. That's why most of
>>us avoid serious injuries.
>> From the
>>Unwise Microwave Oven Experiments
>> web site:
>> Things are different in a microwave oven. The
>> water gets hot but the container usually
>>does not. There are no "boiling-bubbles"
>>triggered by a hot metal pot. Without those
>>bubbles to cool it, the temperature of the
>>water rises far higher than 100C°. We
>>call this "superheated water." Superheated
>>water is just waiting for some sort of
>>trigger which will let bubbles form and allow
>>boiling to commence. If the water becomes
>>hot enough, a few bubbles will appear, but
>>these quickly rise and burst, and the
>>water isn't cooled much at all. In the
>>microwave oven, even if your mug of water
>>is bubbling slightly, don't trust it, since
>>it's temperature has risen so high above
>>100C° that bubbles are appearing spontaneously.
>>If some unwitting victim should pour
>>a soluble powder into the superheated water,
>>this will carry thousands of tiny air
>>bubbles into the water. Each of these micro
>>bubbles expands into a 1cm steam bubble,
>>and the result is a huge "explosion" of hot
>>froth. It's just like dumping ice cream
>>into root beer, but the froth can be so violent
>>that the hot water sprays into the
>>air.
>> If you're worried about explosions over
>> superheated liquid, you can virtually eliminate
>>the possibility of its happening to you by
>>simply leaving some non-metallic object
>>(such as a wooden spoon or stir stick) in the
>>cup or bowl when you boil liquids in
>>your microwave. It may not be necessary, but
>>it won't hurt anything either. Peace
>>of mind rarely comes so cheaply.
>>
>>earlier, Phil Scovell, wrote:
>>>This is one to look up on snopes I guess but I have heard of this before and
>>>things falling apart after being super heatened in the microwave.
>>>
>>>Phil.
>>
>>John
>
John
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