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, 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 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 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.’

This entry was posted in accidents, burns, microwaves, people, things, water and tagged , , , , , . Bookmark the permalink.

16 Responses to Microwaving water

  1. SKL says:

    Wow, that is good to know. Sounds like a mistake I would make.

  2. Lucy says:

    Definitely good to know! thanks. I have a kettle that boils my water for me (love it), but when I’m visiting other people I often use the microwave. So thanks for letting me know 🙂

  3. Karen Joy says:

    I heard this years ago,on some news program.Ive always remembered the 2 minute rule and never put water in longer than that.Im still really careful when I take it out.

  4. Joy says:

    You know, I do this all the time too. I just love ramon noodles and eat them a few times a week for my lunch. I also make a lot of rice. I now put a little wooden spoon thing I got years ago from Pampered Chef in there when it’s done for a minute. This was very good to know. Sometimes I can see the water boil and sometimes I can’t. I always wondered about it.

  5. Joy says:

    Come on Darryl. Tell your microwave stories.

  6. Ellen says:

    I never knew this! I am surprised no one told me before, I have two sons, who are chefs and a husband who is an engineer! They for sure know this, but did not tell me! Thanks for letting us know, Pammyann!!

  7. Nikki says:

    Wow, good information. I rarely use the microwave for anything though. I use my stove a lot. I do use it for tea, but I have a tea bag in it.
    You know, I do not own a wooden spoon! LOL I will remember this one, and will be sure to tell Bailey. He uses it more than anyone.

  8. Laura says:

    I actually had this happen to me. I often make egg white omlettes for breakfast, and love chopped asparagus in them. I blanch the asparagus before sauteeing to soften it, and use a little bowl of microwaved water to do it.

    So, one morning, I put a little pyrex dish with about 1/2 cup of water in it, in the micro, and hit the button. 2 minutes? I don’t know… enough to get hot. Then I went to chopping my asparagus. When the micro dinged, I took my little handful of asparagus, held it over the hot water, and dropped it in.

    The second that asparagus hit the water, it exploded. All over the side of my hand, giving me a second-degree burn from the base of my pinkie down to my wrist.

    Now, every time I microwave water, regardless what size or type of container that I use, I simply float a toothpick on the surface of the water, or put an old wooden spoon in the container. It causes the surface to be broken, allowing the water to boil.

    • Nikki says:

      Toothpick!!!! Geez, I didn’t even think about that! That sounds painful, did it leave a scar?

      • Laura says:

        No… no scars. I was fortunate that I was in the kitchen, and I immediately got my hand under cool water. And my doc got me right in – between appointments, no less – and gave me some sort of miracle cream that really helped a lot.

  9. Darryl says:

    I dont use the microwave very often but sometimes just to heat water, But only put it in for 30-45 seconds. Very good to know I have never heard of this before. Here is the opposite if you put a bottle of beer in the freezer unti just about frozen it will be in liquid form until you open it and then it will freeze??

  10. joz1234 says:

    another idea, stick a toothpick in the water.

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