Microwave Hazards(A long but useful one)

[Kimmie]

I thought this would be worthy of note:

The following information is received from a reliable source. Please circulate this to so many people for their precautionary measure.

I feel that the following is information that anyone who uses a microwave oven to heat water should know. My friend 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 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. It is however a much safer choice to boil the water in a tea kettle.

Please pass this information on to friends and family.

General Electric's response:

Thanks for contacting us, Mr. Williams. 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. I hope this helps. Should you need any further assistance, please contact us.

Here is what a 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 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. 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.

[Anneke]

If only people would read instructions...

[alexia]

Thanks, I emailed this information on. Though why anyone would heat their coffee more than 1/2 - 1 minute....

[Athenaeus]

Thanks for that Kimmie!

I think it's in the instructions that you must let ANYTHING stand in the micro 30sec after heating it!

[KyleW]

First time I've ever been glad I don't have a microwave

[phatch]

I smell an urban legend.

No first hand experience, only one company response, and even then, not a dominant builder of the product, Friends of Friends, unnamed alleged reliable sources, descriptions beyond science, fixes that are self contradictory and so on.


OK. First, to superheat water requires higher than normal pressure. A microwave is not a pressure cooker. It won't and physically can't happen. Microwaves aren't magic. They are very well understood. If the microwave was high pressure, The door would have blown out of his hand as he opened it and the water would have erupted out of the cup then as the pressure changed.

Second, cups and other common microwave items are flawed, They contain imperfections that cause liquids to bubble before they are technically at the boiling point. The liquid will certainly bubble. This is even before the scratches are taken into account. Surfaces are inherently imperfect. High school science teachers as authorities? Please. More on this in a bit.

Third, oven variances. Manufacturer and power of the oven isn't known. I have two microwaves. In the older low powered one, it takes about 1:45 to boil 1 cup of water. Sad, isn't it. In the newer one, 1 cup boils in about 40 seconds. It's much higher wattage too.

Fourth, Heat behavior. The science teacher's explanation is wrong. Thermodynamics is well understood. Look at the explanation. Bubbles release the heat? No. Water has a clearly understood reaction as it transitions from water to steam. It takes a known and fixed amount of energy for this to happen. The water will never pass the boiling point in temperature as long as it is liquid under normal pressure, which we have established as normal in the microwave. The water will continue to absorb energy to convert molecules to the steam state, but the temperature stays the same. This is why a steam burn, even though at the same temperature as the boiling water, is much worse. There is more energy in steam to burn you with.

Fifth, logic and the law. The person who had the accident does not verifiably have a GE oven. Why does an unaffiliated person write to GE for an answer on an unknown product? Why would GE give instructions on a product that wasn't theirs. They wouldn't. Corporate liability and lawsuits would destroy them.

Bogus through and through.

Phil

[ShawtyCat]

Well, actually Phil, this does happen with microwaves. If you have a container with very smooth sides, such as a new coffee cup, that does not allow the bubbles to form somewhere the water does superheat. I doesnt boil. It just gets very, very, very hot. The technique is to place a wooden skewer into the cup with the liquid you want to boil in order for the bubbles to form.

I have done experiments on this. Yes if your cup had a few imperfections on the inside the bubbles will form etc. etc. But with most of the cups tested the water did erupt out of the cup when it was jostled or being removed from the microwave.

There was also a show on the Discovery Science Channel on this. If everyone did these tests are wrong.............well, I don't know what to say to you. I wouldn't recommend running a test yourself unless you have a long instrument with a grasp at the end in order to lift the cup out of the microwave. This phenomenon can cause very severe burns. It is definately not bogus. (Oohhh I love a good discussion)

Jodi

[phatch]

The jostling creates nucleation sites that form allow the bubbles to release. While true, it is technically possible, the weight of the water creating the necessary pressure, it's difficult to get it out to your face to blow up.

Also, it is a well known urban legend, even with some basis in possible fact.

www.snopes.com is devoted to urban legends. Very interesting reading. For specifics on this one see: http://www.snopes.com/science/microwav.htm Note that it's veracity is rated "sort of"

Phil

[Isa]

It is true. There was even a piece about it on 60 minutes. The water will splash as soon as you will put a sppon or anything else in it. It's cause by a reaction that happends if water is heated pass the boiling point.

[Svadhisthana]

The microwave is a good choice, too. Just be sure to use a microwave-safe measuring cup, bowl, vessel of some type with a wooden skewer or chopstick placed inside. See, in order for water to actually boil, there's got to be a niche, a scratch, an imperfection, somewhere on the inner surface of the container so the bubbles can form. If the container is super-smooth and the microwave super-strong, the water could super-heat without actually boiling. Then you reach in for the container, you give it a jiggle, and ka-boosh, it boils explosively ... as in all over you. The skewer or chop stick gives the bubbles a place to grow thus diffusing the situation. Now besides the boiling vessel we are going to need a pot.

Alton Brown-"Good Eats"


I've seen it happen.

[Athenaeus]

Yeap.

Another one suggested to place a plastic spoon while you boil water in the micro

[Kimmie]

So it's not such a hoax after all is it!

[LotusCakeStudio]

This very thing was mentioned on the local news here several weeks ago. They showed two women who had damage done from heating water in the microwave. Was NOT a pretty site!