Microwave Warning:
Do not heat liquids in a microwave
for more than 2 minutes.
> (
Share this important information with your families and friends.)
>
> ''A 26-year old
person decided to have a cup of coffee. He took a
> cup of water
and put it in the microwave to heat it up (something
> that he
had done numerous times before). I am not sure how long he
> set
the timer for, but he told me he wanted to bring the water to a
> boil.
When the timer shut the oven off, he removed the cup from the
> oven.
As he
looked into
the cup,
> he
noted that the water was not boiling, but instantly the water in
> the cup "blew
up" into his face. The cup remained intact until he
> threw it out
of his hand but all the water had flown out into his
> face
due to the build up of energy. His whole face is blistered and
> he has 1st and 2nd degree burns to his
face which may leave
> scarring. He also may have lost
partial sight in his left eye.
> While at the
hospital, the doctor who was attending to him stated
> that this is fairly common occurrence
and water (alone) should
> never be heated in a
microwave oven. If water is heated in this
> manner,
something should be placed in the cup to diffuse the energy
> such as a wooden stir
stick, tea bag, etc. It is however a much
> safer choice to
boil the water in a
tea kettle.
>
> General
Electric's response:
> Thanks
for contacting us. I will be happy to assist you. The e-mail
> that
you received is correct. Microwaved water and other liquids do
> not always bubble when they reach the
boiling point. They can
> actually get superheated and not
bubble at all. The superheated
> liquid will bubble up out of the
cup when it is moved or when
> something
like a spoon or tea
bag is put into it.
> To prevent
this from happening and causing injury, do not heat any
> liquid for more than
two minutes per cup. After heating, let the
> cup stand in
the microwave for thirty seconds before moving it or
> adding anything
into
it.
>
> Here is what a
science teacher had to say on the matter: "Thanks
> for the microwave warning.
I have seen this happen before. It is
> caused
by a phenomenon known as super heating. It can occur anytime
> water is
heated and will particularly occur if the vessel that the
> water is
heated in is new, or when heating a small amount of water
> (less
than half
a cup). What
> happens is that
the water heats faster than the vapor bubbles can
> form. If the cup is very
new then it is unlikely to have small
> surface
scratches inside it that provide a place for the bubbles to
> form. As
the bubbles cannot form and release some of the heat that
> has
built up, the liquid does not boil, and the liquid continues to
> heat up well
past its boiling point. What then usually happens is
> that the liquid is bumped or
jarred, which is just enough of a
> shock to cause the bubbles to rapidly form
and expel the hot
> liquid.
>