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I received this in an email.  It looks sound advice so I thought I would pass it on.  I never really boil water alone in a microwave but if you do...

Microwaving  Water!

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 buildup 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).


General  Electric's Response:


Thanks  for contacting us. 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 heatany 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:  I have seen this happen before. It is caused by a  phenomenon known as superheating. 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 has built up, the  liquid does not boil, an d 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

Replies sorted oldest to newest

Reference:
ooooo that sounds good. I usually just stab at a packet of mixed veg and stick the whole lot in. I went in to a Lakeland store (in Bluewater) with my husband once, and he followed me the whole way round replacing stuff that I'd put in to my basket. I could have bought every single thing in that shop that day
I get the catalogues sent and I know just what you mean, I have to give myself a very stern talking to when I leaf through them
squiggle
Reference: Scotty
Exactly. My pal microwaves her coffee..it comes out like a bubbling volcano. She has to keep adding milk, while she`s drinking it, to cool it down.
 I only ever did it once (quite recently) and not only did I almost cook the glaze off a vintage mug in 20 seconds, the liquid inside was like something from the centre of the earth
Never again.
P.S: I see you, Ms bean  
Demantoid
Yogi I think that the warning does refer to all liquids.  I thought it was especially thought provoking about using new cups or other vessels.  No scratches equals no places for the bubbles to gather.  When I heat milk I usually do it in a plastic jug with loads and loads of room.  Also the bit about the resting time in the microwave seems sound advice too. 
squiggle
I can't live without the microwave... for defrosting, for heating up, for steaming veg... & for cooking the dog the odd chicken breast... 

however... dunno what it is with chicken breasts but the last two I did exploded all over the inside of the microwave...  the dog didn't mind having shredded chicken...  I was less enthusiastic about having to clean it all up though!

(& Suzy...  I am the queen of stealth purchasing    Recently I'd maxed my card & asked hubby if he would buy me an audiobook (for the Essex - Surrey schoolrun)... he said yes, & gave me his card.   This has meant that his card details were in my iTunes account..   wayhay!!!   He said to me last night "baby... do you think you could stop spanking my card on iTunes... "  - twas good whilst it lasted! )
Dirtyprettygirlthing
My housemate always gives her coffee a quick zap in the microwave, because she says once you add milk it cools it down so when you get to the bottom of the cup its not nice...I have never done it and don't think I leave coffee around for long enough to go cold haha.
Its very true about the scratches and the bubbles though, thats why a good pint glass will always have something etched on the bottom, to create the bubbles, and why crystal champagne glasses are etched inside.
Trixy

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