Microwave Experiments Cause Sponge Disasters

gollum123 writes "Reports about a study that found microwave ovens can be used to sterilize kitchen sponges sent people hurrying to test the idea this week — with sometimes disastrous results. A team at the University of Florida found that two minutes in the microwave at full power could kill a range of bacteria, viruses and parasites on kitchen sponges. They described how they soaked the sponges in wastewater and then zapped them. But several experimenters evidently left out the crucial step of wetting the sponge. "Just wanted you to know that your article on microwaving sponges and scrubbers aroused my interest. However, when I put my sponge/scrubber into the microwave, it caught fire, smoked up the house, ruined my microwave, and pissed me off," one correspondent wrote in an e-mail to Reuters."

A bit silly?

[Ckwop]

How else did they expect it to work? Of course you need the god-damn water in the sponge. Microwaves have a wave length measured in the centimetre. The size of a bacterial spore is a couple of orders of magnitude smaller The size of a bateria is a lot smaller than this again.

This means that if you wanted to destroy the blighters with radiation alone you have to choose a frequency a lot higher than microwaves, otherwise there will be areas in the minima of the standing wave that won't heat sufficently to kill the microbes.

The mechanism for steralisation is through the formation of steam that kills the majority of the nasties - not the microwave energy itself.

Simon

Stupid People, Stupid Method

[StarWreck]

The microwave steralizes the wet sponge because it makes the water hot enough to kill anything living. The same effect can be had by dunking the sponge in a pot of boiling water.

No matter what you do...

[dtmos]

Note that even the original University of Florida press release [ufl.edu] begins

PLEASE NOTE: To guard against the risk of fire, people who wish to sterilize their sponges at home must ensure the sponge is completely wet. Two minutes of microwaving is sufficient for most sterilization. Sponges should also have no metallic content. Last, people should be careful when removing the sponge from the microwave as it will be hot.

*sigh*

Sterilising Baby's bottles

[REBloomfield]

of course, those of us with children and bottle sterlisers know that placing water and objects in a microwave leads to the steam cleaning them... "well duh" was my reaction when i saw this "news" item yesterday....

Re:You're being naive/optimistic

[jrumney]

People may not understand microwaves, but the original article I saw gave the following advice:

• Wet the sponge first. Dry sponges will not heat evenly and may catch fire.
• Keep an eye on the sponge while it is in the microwave and stop the microwave immediately if there is any sparking.
• 2 minutes should be enough for most bacteria, but never microwave your sponge for longer than 10 minutes.

Maybe some news sources edited the article down to a short filler piece and left out some of these crucial details.

But do _you_ understand?

[KnightTristan]

... how else did _you_ expect it to work?

A simple question for you: water molecules, are they larger or smaller than the bacteria and spores to be killed?

Last time I've checked, the wavelength used in the microwave is about 12.5 cm. Sure, the bacteria are much smaller than that, but is it at all relevant?

KnightTristan

Re:No matter what you do...

[rsidd]

From last paragraph of TFA --that's not the original release, that's the advisory the university issued after all these people burned their sponges.

Re:Ignorance != Stupidity

[Anonymous Coward]

Calling these people stuipd only makes you look like an arrogant asshole. For most people, a microwave is a black box contraption in their kitchen that makes food hot. Sure, they also know that you shouldn't put a fork or knife in, but have no idea why. This isn't because they're stupid, it's because they're ignorant about the inner workings of that particular machine in their kitchen.

No, it's because they're stupid. No knowledge of inner working of microwave required to understand that putting flammable things into a device that makes them hot IS NOT A GOOD IDEA.

Re:Ignorance != Stupidity

[Tony Hoyle]

no, they're not stupid. they put shit in a "black box that makes food hot" and it caught fire. WOW! color me surprised. I'd say that's pretty stupid.

No. The media told them "if you put shit into a black box that makes food hot it will sterilize it".

So they did. And it caught fire... because the media forgot to mention that you should use *wet* shit.

That is totally different to waking up one morning and trying to microwave a random object to see what would happen.

Re:Clearly, evolution as a system has failed...

[inviolet]

Evolution does not have any right or wrong directions. That's devolution fallacy.

Humans set goals which evolution can work for or against. In the case of the goal "All humans become smarter and more peaceful, and achieve worldwide safety and comfort, and stop shooting each other over which hand the invisible man in the sky wants you to wipe your a** with", the goal is nearly universal, at least among men who have thought at all about the optimal future state of mankind.

It is implied, and obvious to everyone except for pedantics like yourself, that value judgments about evolution are using that goal as the standard of value. And therefore evolution can move in 'right' or 'wrong' directions, relative to that goal.

I knew

[kilodelta]

Because microwave ovens work best by vibrating water molecules. As they vibrate friction causes them to turn to steam which is what sterilizes the sponge in the first place.

Re:Incoming lawsuits in:

[ArsenneLupin]

Since a microwave does a great job of restoring a piece of dried bread to something edible (by heating and expanding what little water is present in it),

Careful here. Dried bread does catch fire when left in the nuker for too long. And sometimes that too long is not long enough to make it soft (I made that experience years ago with a dry piece of French baguette... maybe different kinds of bread behave differently...)

Neat.

[Valdrax]

How else did they expect it to work? Of course you need the god-damn water in the sponge. Microwaves have a wave length measured in the centimetre. The size of a bacterial spore is a couple of orders of magnitude smaller The size of a bateria is a lot smaller than this again.

So, are you suggesting that any body shorter than the wavelength of microwave radiation (12 cm) will be left unheated? Neat! That must be why my pizza rolls are still frozen when I get them out.

...Or maybe someone who feels superior to "the masses" need to really review the concept of dielectric heating. [wikipedia.org]

Boiling too easy?

[uberjoe]

Why not just put your sponges in a pot of boiling water for two minutes and skip all the exploding parts? It even works on metal scouring pads.

Re:But do _you_ understand?

[Dr. Hok]

Last time I've checked, the wavelength used in the microwave is about 12.5 cm. Sure, the bacteria are much smaller than that, but is it at all relevant?

Actually, the parent does say why it is relevant: there will be areas in the minima of the standing wave that won't heat sufficently to kill the microbes.

The microwave radiation in the oven is a standing wave. This means there are areas where the radiation is (close to) zero, and the buggers there won't be heated, even if they contain water. Put a sufficiently large chocolate bar into the microwave oven for some seconds and observe the patterns of solid and soft chocolate. Then eat the chocolate, of course.

The water (steam) is needed to average the heat out over the whole sponge to kill all bacteria in it.

Re:Stupid People, Stupid Method

[AK Marc]

Actually, your dishwasher is not going to sterilize anything,

Just because you don't know how to work a dishwasher doesn't make your false statements true. My dishwasher has a little button marked "sterilize." I don't have the manual in front of me, but I believe that when that button is pressed, the wash cycle hits >160F for no less than 5 minutes. Perhaps you should stop buying your dishwashers at Wal-Mart and you'll realize that there are other settings than just "on" and "off" on dishwashers.

Re:Clearly, evolution as a system has failed...

[hempola]

I wish there was a negative comment modifier called: "Stop with the overused, paranoid theory that robots will ruin the economy by unemploying uneducated people".

**(For the record, I don't downmod comments)**

The whole robots/unemployment thing has been hashed out repeatedly, argued even before there was a term/name for "robots". The following is the outline of personal notes i used for a speech i had to give in speech class a few years ago:

WHY ROBOTS WON'T TAKE ALL JOBS.txt

first, if everyone loses their jobs and have no money, there will be no one buying anything the robots make or services the robots offer, and then the companies won't be able to get any money to build and maintain the robots.

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nor will we loose all the current type of jobs, like service jobs.

why? people will not allow this to occur. we need to be able to talk to an actual person. computers can't tell if you are getting frustrated.

like ATMs didn't replace all the bank tellers, computers can't replace the personal touch. how many of y'all get pissed-off using those automated call systems? "press two if business, press three if residential, press four....."

Arby's offered automated ordering - touch screens where you could order your own food. a lot of people did not use it. it was not successful.

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automation will only be used where it can reduce costs, wich means lower prices, which means we can buy more stuff. it makes us all richer.

7000 years ago... the invention of the hammer unemployed a lot of people who used rocks (they prolly went into farming).

printing presses wiped out the hand copied manuscript industry, but made books available to everyone.

people always find something else to do, or else we would all be unemployed already!

for example: the robot industry will create millions of new jobs to program/design/manufacture the robots

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funny: how about buy your own robot and then have it go to work for you, while YOU get paid. now THAT's labor saving!