microwave!

microwave warning:


A 26-year old man 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
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 suddenly 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 a 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.,
(nothing metal).


It is however a much safer choice to boil the water
in a tea kettle.


*General Electric's [GE] Response: *


=Thanks for contacting us, I will be happy to assist you.
The e-mail that you received is correct. Micro waved 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 our local 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 of 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 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. The rapid formation of bubbles is
also why a carbonated beverage spews when opened after having been
shaken."


If you pass this on you could very well save someone from a lot of
pain and suffering