Have you ever experienced the phenomenon of
superheating water in the microwave? Superheating is what happens when water is heated past its boiling point, yet doesn't form the bubbles we associate with boiling. Superheated water is dangerous because it looks like it's cooler than boiling, yet may actually be several degrees hotter! Also, when the superheated water is disturbed, as by bumping the container, stirring the water or adding something to it, the water may suddenly boil or vaporize into burning steam.
Minimize the Risk of Superheating
You can lessen the chance of superheating your water by using the minimum cooking time for water or by providing starting bubbles that will allow the water to boil more freely. These bubbles can be introduced by something as simple as using aerated water from the tap. Glassware that is slightly rough or scratched is less likely to superheat water, too.
The Myth About Superheating Water
Some people believe only pure water will superheat. This is not true. Water with impurities, such as tap water, can superheat. It is simply less likely to superheat because tap water usually comes straight from the tap and contains a lot of air. Tap water that has been sitting on the counter for a while can superheat. Many homogenous liquids can superheat, including coffee and tea. Similarly, it is untrue that you can only superheat water in a microwave. It is true that it's easiest to superheat water in a microwave, particularly one that does not rotate the food, but you can superheat water on the stove or other heat source.
Share Your Experience
Have you experienced superheating? Feel free to share your experience, particularly if you superheated a liquid other than pure water.
Comments
I am so glad to see this post today.
I actually superheated coffee just moments ago. It was the first time that anything like this had ever happened to me. My coffee maker is fairly cheap, and doesn’t actually make good hot coffee. So I will often microwave it for 30 seconds to a minute to make sure that its hot enough for my sugar to melt it in afterward.
Today, I took the coffee, freshly brewed, and did what I normally do. I sat the hot mug gently on the counter. It was still. I then dipped in a bamboo skewer (what I typically use to stir my coffee) and wham! It bubbled uncontrollably and exploded out from the mug. Luckily I was standing far enough back that it didn’t get on me anywhere but my hand on a couple of small places. But still, it was frightening.
The reason I was looking for an article like this is because my boyfriend (who was in the room at the time of the incident, but not paying attention to it) didn’t believe me when I told him what had happened. He thought that I was just being clumsy and spilled it. He believed that only distilled or pure water could be superheated.
Now, with your help, I feel that I can successfully prove what happened today. So thank you!
I just experienced super heating of water. It was tap water … aerated … in a large mug, for tea. The microwave was one that rotates the contents, and not too smoothly at that. I did heat it several times in a row since it did not boil … I thought it was just not heating well in the cheap oven.
When it finally appeared to be hot, putting off a wee bit of steam, I took it out. I set it in a saucer, and proceeded to put the tea bag in. When it touched the water, the water started boiling violently as if spattered directly on a red hot stove top.
Just goes to show most of the “rules” didn’t apply in this case … just the over-heating.
I actually attempted to superheat water in the microwave. After several attempts, the water boiled at 94.9 celcius. So I switched containers and got liquid water up to 105.0 celcius. At that point, I put a long handled fork in the water, and the water splashed violently all over the microwave. The water was superheated and reacted violently with the introduction of a nucleation site. It did clean the microwave quite nicely, but that is definitely not the safest way to clean it.
I for one do not have to attempt this experiment since it is untrue. It is a proven FACT that water starts to boil at 212 degrees. This is when it changes state and turns to steam. Any additional heat that is added is carried away in the steam. Water will not exceed 212 degrees under atmospheric pressure therefore will not superheat (as you call it) in a microwave as described.
I know water can explode from a cup as the burns on my hand are real and painful. I had about 12 oz of premade coffee that had cooled down but still fairly warm. I always set the timer for 2 minutes when heating room temp liquid. I forgot adjust duration down. After two minutes, I looked at cup and clearly saw no boiling. I had a towel in my hand that I used to grab the cup. The instant the cup moved, nearly the entire glass of coffee blew out and all over including my hand. I immediately placed my hand in ice water but it still killed nearly all the skin on the back of my hand and left a decent sized scar.
It can happen but seems to be a rare occurrence. I am surely more careful pulling hot items from the microwave.
I remember the first time I superheated water. … I was about 12 and looking for an easy way to make Jello. I tried several times to heat the water to boiling in the microwave and it just wouldn’t work! So, I decided to see if the gelatin would dissolve in whatever temperature I had reached. BIG MISTAKE! Sticky redness all over the place! Over 80% of the water immediately jumped out of the cup.
I have been playing with superheated water the last couple of days – trying to find the point where my daughter can see the reaction without it bursting into her face. It looks like with my current microwave and hot water heater setting, 1 minute and 18 seconds will be perfect.
Nice person that she is, my wife heated tap water for my morning tea. I stayed in bed a while before going to the microwave. She said I would probably need to reheat the water. I hit the ‘add 30 seconds’ and it didn’t boil so I hit it again, then again. Still no boiling! While I was looking thru the door there was an explosion. The door blew open and hit me in the mouth. Six stitches and a repaired broken tooth later I can attest to the reality and power of this dangerous phenomenon. Don’t try this at home, or anywhere else for that matter.
Happened at the office twice in a commercial microwave with no turntable using an uncovered new glass Pyrex measuring cup with filtered hot tap water.
Very similar to mike above, I began with preheated water. After the initial minute and a half the water wasn’t boiling so I added 20-30 seconds 2 or 3 times more.
The first time it happened inside the microwave but I didn’t see it so I wasn’t sure what happened. I cleaned up and tried again.
The second time it happened upon removal. The water EXPLODED and seemed to go everywhere — on me, a coworker, and the 9′ high ceiling tiles. Fortunately, neither me nor the co-worker got burned.
I googled exploding water and for 3rd attempt I put a plastic knife in the water while heating and it boiled normally in less than a minute.
@steve r – you don’t have a clue, that’s a FACT
Steve -
Water boils at 100 CELSIUS, and 212 FAHRENHEIT. Two different measuring systems. One is the metric system, and the other is US Customary. They use Celsius in Europe and Canada, and everywhere else besides uuuuhh-merica.
It is true. Try it.
Water does not always boil at 100 degrees Celsius, this is the boiling point ar sea level or 1 bar atmospheric pressure. Boiling point on Everest for instance is 69 degrees Celsius. As for super heated fluids, I don’t know, never experienced it.
Steve, normally that is true, at atmospheric pressure at sea level, water will boil at 100C, or 212F. But superheating does happen. This wikipedia article describes how water can be heated up to 374C, or 705F.
Since making that post, I’ve been able to heat liquid water up to 120C, or 248F, using nothing more than bottled water, a brand new measuring cup, and a microwave. This isn’t a safe experiment to try, and I haven’t tried it in a number of months because water heated to that temperature will instantly cause 3rd degree burns. It is definitely not a myth.
I made jello last night the way I always do. I was heating 2 c. of tap water in a 4 c pyrex measuring cup. The *fourth* batch took more time to boil. I was standing around waiting for it when the microwave door flew open – kinda like Mike described,above – and 1 and 1/2 c. of water went everywhere! Only 1/2 stayed in the measuring cup. I have no way to reproduce this phenomenon since it happened only once. I did the exact same thing for the prior 3 batches. And I’ve done it dozens of times in the past with no problems.
I think Steve should come back and own up that he was a pre-teenager when he wrote that comment so that he does not have to feel silly for the rest of his life