To nuke or not to nuke

SHMBO often heats plates in the microwave. She places a little water on them and hits them with a 100% blast of whatever is in the microwave. She has done this for many years and in fact for many years with the plate shown below, and it's mates of course. We have had this crockery for at least twelve years.

However the other day something different occured. Either insufficient water or too long a nuke time or fatigue resulted in the plate developing a little volcano (I was going to say nipple but that probably would have been deleted) in the centre of the plate on both sides.

This deformation is almost central. In fact the third picture is of the plate spinning, not that you can see it:rolleyes:. Just rotating it by hand it will spin for over three minutes.

I have several questions as a result of this phenomena (the damage to the plate not the spin time:D)

1. What has caused this rupture of the plate to occur and also why after all this time?

2. If microwaving does this to the plate, what does it do to the food and is it truly safe?

3. The plate has a checkered pattern on the perimeter and when spun appears to rotate in the opposite direction to that in which it was spun. Wheels on vehicles appear to do this too. I appreciate it is an optical illusion, but what really happens?

Just on the second point I have a naturapth friend, who maintains that micowaved food when placed under a microscope has changed dramatically compared to coventionally heated foods.

Interested to hear your thoughts.

Regards
Paul

I'm not 100% sure, but over time there may have been a crack in the glazing of the plate, which has allowed water in under the glazing. When the microwave heated it, the water inside expanded, causing the bubble.

Microwaves work by producing electromagnetic radiation of a wavelength that excites water molecules, heating them up (and therefore indirectly heating up the surrounding stuff that contains the water). You can get an idea of the actual wavelength, as the holes in the grill over the front door are a little smaller than the microwaves' length. Your naturopath friend was right in that heating food by any means will permanently alter it chemically, but there is nothing 'special' about microwave radiation; it is a a lot shorter wavelength than radio waves, a bit shorter than tv signals, a bit longer than infrared radiation, a fair bit longer than visible light, and a lot longer than UV (all of which are forms of EMR).

As to the third point, I hope someone else can say, because I would love to know too.

1. Be thankful it stayed in one piece and didn't take out the microwave. It might have if left longer and that pimple burst. I once saw the after effects of a superheated air bubble in the base of a (well used) ten litre cooking pot full of spag bog. The only part of a domestic kitchen untouched was above the fridge directly opposire the stovetop.

2. A few weeks ago, a listener claimed an ABC talkradio host was dangerous in her support for microwave cooking (and challenged her to mention it on air). In return she very effectively took apart the anti-microwave every claim the listener had quoted and included references. I think she lost a fan.

3. Stroboscopic effect
Stroboscopic effect - Wikipedia, the free encyclopedia
I can't remember all the intracacies but they can be fun. It also has a practical use, or once did. Some gramophone disc manufacturers used to incorporate them into the disc label. The listener would use the pattern to set the speed for that record's playback. Too fast - it moved one way, too slow - the other way, just right - stationary. I've even seen it on more modern B&O turntables.

A quick search of the interwebs reveals a lot of articles on the dangers of microwaves but mostly on sites that believe in UFO's or homeopathy. :)

Thank goodness this topic has at last come up as it will prove to my wife that I am not the only one who lies awake at night thinking about these gadgets. At this early stage, my obsession is centred around the fact that the turntables of all microwaves seem to rotate exactly a whole number of revs in one minute so that the handle of the cup is facing you when it finishes if you press a whole number of minutes. Ours does 5 RPM, my son's does 6, a friend's does 4. So I now know my 12 times table - pressing 36 secs or 48 or whatever so that the handle faces me when it's finished. Tomorrow I must get a life.

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Originally Posted by Bushmiller

However the other day something different occured. Either insufficient water or too long a nuke time or fatigue resulted in the plate developing a little volcano (I was going to say nipple but that probably would have been deleted) in the centre of the plate on both sides.

This deformation is almost central. In fact the third picture is of the plate spinning, not that you can see it:rolleyes:. Just rotating it by hand it will spin for over three minutes.

I have several questions as a result of this phenomena (the damage to the plate not the spin time:D)

1. What has caused this rupture of the plate to occur and also why after all this time?

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water penetration of a microcrack in the glazing.
the microcrack most probably developed through handling of teh plate and/or using the dishwasher

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2. If microwaving does this to the plate, what does it do to the food and is it truly safe?

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as most know water is that nasty chemical called H2O. Radiation at the right wavelength causes the water molecules to vibrate. The greater the vibration the "hotter" the water molecule gets. This heat is transferred to the food.

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3. The plate has a checkered pattern on the perimeter and when spun appears to rotate in the opposite direction to that in which it was spun. Wheels on vehicles appear to do this too. I appreciate it is an optical illusion, but what really happens?

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light from AC power sources pulses 50 times per second -- think of a strobe light flashing 50 times per second
your brain interprets the flashes as being a constant light -- but when you get a pattern spining at the right speed the flashes will either make the pattern appear to stand still or spin backwards

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Originally Posted by dabbler

1. Be thankful it stayed in one piece and didn't take out the microwave. It might have if left longer and that pimple burst. I once saw the after effects of a superheated air bubble in the base of a (well used) ten litre cooking pot full of spag bog. The only part of a domestic kitchen untouched was above the fridge directly opposire the stovetop.

.

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It is more likely water that penetrated a crack or tiny hole. Air rarely cases anything to explode cos its pretty good at compressing. But when water boils it suddenly all turns to gas and does a really good job of propelling things across rooms, or pushing trains up hills.

How it has actually grown a lump in the plate is a bit weird. I have seen pottery do that in the firing. But not years after like that. Perhaps there is some iron in the clay body that cased that local bit of clay to get even hotter and distort. Why its not cracked apart is also a mystery. I guess the stresses were able to go out into the bubble rather than sideways in the plate. :think:

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Originally Posted by snowyskiesau

A quick search of the interwebs reveals a lot of articles on the dangers of microwaves but mostly on sites that believe in UFO's or homeopathy. :)

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No problems, provided you are wearing your foil hat. :D

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Originally Posted by snowyskiesau

A quick search of the interwebs reveals a lot of articles on the dangers of microwaves but mostly on sites that believe in UFO's or homeopathy. :)

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Or naturopaths

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Originally Posted by Bushmiller

Just on the second point I have a naturapth friend, who maintains that micowaved food when placed under a microscope has changed dramatically compared to coventionally heated foods.

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That's it - I'm getting rid of my microscope immediately as they are obviously dangerous :wink:

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Originally Posted by snowyskiesau

A quick search of the interwebs reveals a lot of articles on the dangers of microwaves but mostly on sites that believe in UFO's or homeopathy. :)

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I still don't know what a homeopath is. Sounds like a gay serial killer.

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Originally Posted by pugwash

I still don't know what a homeopath is. Sounds like a gay serial killer.

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That cracked me up. :roflmao:

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Originally Posted by pugwash

I still don't know what a homeopath is. Sounds like a gay serial killer.

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I'm guessing you wouldn't be overly receptive to a holistic approach either:p.

Regards
Paul

How microwaves work (physics equation version):

"The water dipole attempts to continuously reorient in electromagnetic radiation's oscillating electric field. Dependent on the frequency the dipole may move in time to the field, lag behind it or remain apparently unaffected.
When the dipole lags behind the field then interactions between the dipole and the field leads to an energy loss by heating, the extent of which is dependent on the phase difference of these fields; heating being maximal twice each cycle."

http://www.lsbu.ac.uk/water/microwave.html

Caution. Contains hard science content; may not be comprehendable by naturopaths, homeopaths, Reki practitioners, aura readers and other snake oil salesmen.

Nifty applet demonstrating it all: http://www.colorado.edu/physics/2000/applets/h2o.html

Thank you for all the input. Further theories most welcome.

It looks like the plate has developed a fault in the glaze and that has allowed water to be absorbed into the pottery itself. When it was heated it "blew" out the surface on both sides of the plate.

We only use the microwave to defrost food and almost never to cook. Occassionally we reheat foods such as bolognaise sauce. I suppose using the microwave is not an earth shattering issue for us. We still have plenty of plates to go yet :wink:.

I have heard of microwave disasters with foods such as eggs (still in the shell) and potatoes still in their jackets.

I like Bob's approach. I'm ahead of him there as I don't have a microscope to cast out. (I'm thinking you might have been a fan of The Far Side.)

Back to the lesser issue of the spinning plate, it definitely appears (is that an oxymoron) to change direction as it slows down. I'm not sure why my brain (even allowing for it's diminutive size and largely unused condition) would assess the direction in reverse to what it knows is happening.

Life's a mystery, but only on the good days:).

Regards
Paul