I tried searching for a thread related, finding nothing titled, here goes.
I have heard warnings So many times that I am NOT suppose to put metal in a Microwave oven AS i put in a can of soup to heat up.
Ok, is their really an issue ??
I know some items like foils and bag ties will ark and burn if accidentally put into oven, but lets limit this for now to a can of Progresso soup.
No issue, as long as you don’t mind buying a new microwave oven.
If there isn’t enough liquid to act as a microwave absorber, the metal will act as an antenna and cause arcing and reflections, which can burn out the magnetron. Don’t do it unless you don’t really care.
Here’s a video of someone microwaving a can of soup. There is some pretty impressive arcing.
Generally the problem occurs in places where the metal is thin and/or pointed. The edge of an open soup can would qualify.
Gah, forgot to include the video:
It could be ok. Metal will act like a reflector, which could concentrate energy someplace, and if it almost creates a loop it can act as a transformer and create high voltage arcs.
But there’s nothing magically bad about it. The entire inside of the microwave oven is made of metal. If I happened to have food on a metal plate, I’d go ahead and put that in, though I might watch for a second when I first started it.
I wonder – it can’t be that unusual to forget, and start the microwave oven before putting the food in it. Do they really destroy such an expensive part if you do that? Or do they provide some kind of practical protection?
Years ago, a few of us got curious what an electron tube would do in a microwave. It filled the oven with brilliant blue white light which streamed out of the door and illuminated the kitchen. We got nervous and stopped it, and opened the oven. The tube was still sitting upright there in the center, as we’d left it. Somebody reached in to retrieve it (gloved I think), and at the first touch the glass all turned to fine dust with a “PFFAF!”
I wouldn’t. A microwave oven is designed to set up a standing wave, which is why you have hot spots and cold spots inside the box. If you put a metal plate in there, you are probably going to get reflections off of it, and those reflections could end up going back into the magnetron (the part that generates the radio waves), which could destroy the magnetron.
The metal plate will also absorb a lot of the radio waves. You’ll end up with eddy currents that heat up the plate. All that energy going into the plate is energy not going into your food, so your food will not heat up as well.
The gray stuff on microwave pizza boxes and the like is actually a metallic coating. It’s designed to heat up, and the heat will brown the pizza dough. Without it, the dough gets hot but doesn’t brown. So if properly designed, metal can go into a microwave. A random metal plate isn’t exactly properly designed though, so what happens with that is more a matter of luck than anything else.
Most likely, the plate will just get hot, but worst case, your microwave’s magentron goes kablooey.
The magnetrons in early microwaves were fairly delicate, and running the microwave without food in it could easily overheat and damage the magetron. Modern magentrons are a lot beefier, so the chance of damage is reduced significantly. You’re not likely to ruin a modern microwave just by running it without food for a short period of time. Turn it on for several minutes though and you can destroy the magnetron.
There aren’t any sort of safety devices to protect the magnetron. A microwave oven is literally just a magnetron, a metal tube (called a waveguide) which takes the radio waves from the magnetron over to where the food is, the metal box that you put your food in, and a simple control circuit. That’s it. Rocket science they ain’t.
Replace the food box with a large antenna and you’ve got a 1940’s style radar transmitter.
As said upthread, arcing usually occurs where charge builds up, like on sharp corners. The tines of a fork will sometimes arc, but usually not in my experience. Take a grape and cut it almost in half so that there is just a tiny bit of skin holding the two halves together and lay it flat on a plate and it will usually arc. Mixed vegetables will arc if they were grown in soil with a high mineral content.
The Never But Metal in a Microwave warning is not set in stone as discussed in this article:
"If you must put metal in your microwave—your house, your rules—the safest option is flat, non-crinkled aluminum foil. With few sharp corners, the electrons have a large area to vibrate over and not many places to get stuck. Sparking isn’t a problem, and the microwave reflections can shield food and keep it cool, like a blanket over a chicken bone you want to protect from burning. Limit yourself, though. The USDA suggests covering no more than one quarter of your food, keeping excess reflections at bay. Thin, flat foils are also part of “crisper” packaging like Hot Pocket sleeves and frozen pizza trays. These foils reflect microwaves, concentrating the energy nearby and cooking the crust a bit more than the rest. (It’s all relative, though. You’re never going to get a nice sear on a microwaved steak, crisper foil or not.)
Beyond that, be wary. Spoons are smoother than forks and should lead to less sparking, and a metal mixing bowl might likewise be cornerless enough, but when you’re explaining what happened to the insurance claims officer, don’t say you heard that justification here."
"If you must put metal in your microwave—your house, your rules—the safest option is flat, non-crinkled aluminum foil. With few sharp corners, the electrons have a large area to vibrate over and not many places to get stuck. Sparking isn’t a problem, and the microwave reflections can shield food and keep it cool, like a blanket over a chicken bone you want to protect from burning. Limit yourself, though. The USDA suggests covering no more than one quarter of your food, keeping excess reflections at bay. Thin, flat foils are also part of “crisper” packaging like Hot Pocket sleeves and frozen pizza trays. These foils reflect microwaves, concentrating the energy nearby and cooking the crust a bit more than the rest. (It’s all relative, though. You’re never going to get a nice sear on a microwaved steak, crisper foil or not.)
Beyond that, be wary. Spoons are smoother than forks and should lead to less sparking, and a metal mixing bowl might likewise be cornerless enough, but when you’re explaining what happened to the insurance claims officer, don’t say you heard that justification here."]If you must put metal in your microwave—your house, your rules—the safest option is flat, non-crinkled aluminum foil. With few sharp corners, the electrons have a large area to vibrate over and not many places to get stuck. Sparking isn’t a problem, and the microwave reflections can shield food and keep it cool, like a blanket over a chicken bone you want to protect from burning. Limit yourself, though. The USDA suggests covering no more than one quarter of your food, keeping excess reflections at bay. Thin, flat foils are also part of “crisper” packaging like Hot Pocket sleeves and frozen pizza trays. These foils reflect microwaves, concentrating the energy nearby and cooking the crust a bit more than the rest. (It’s all relative, though. You’re never going to get a nice sear on a microwaved steak, crisper foil or not.)
Beyond that, be wary. Spoons are smoother than forks and should lead to less sparking, and a metal mixing bowl might likewise be cornerless enough, but when you’re explaining what happened to the insurance claims officer, don’t say you heard that justification here."
Source: https://thetakeout.com/we-asked-a-physicist-why-can-t-we-put-metal-in-the-mic-1798253143
I routinely leave my spoon or fork in soups or highly liquid foods I’m heating up because the percentage of the metal surface is much less than what I’m heating up. Sometimes there a small spark, especially if the fork or spoon handle hits the side of the oven, but as noted in the article, something flammable is required to start a fire. Soup’s not going to burst in to flames!
CD’s and DVD’s make a very nice display in a microwave.
With the proper setup you can even use consumer ovens to melt aluminum and iron.
I once put one of those aseptic boxes (Tetra Brik) in a microwave and found out that was a bad idea. But at least I solved a minor mystery I’d been wondering about. The box was not sealed, in fact the pour spout had broken out of the box and there was only about one serving of soup left in it. So I thought I’d just heat it up in the box.
It turns out that the box has aluminum foil in its construction and it immediately started sparking. I quickly shut it off and did not apparently damage anything. But that at least answers how those things are considered recyclable. They obviously just recycle the aluminum and burn off the rest of the package.
Gives a whole new meaning to the phrase “burn a CD”.
Turkey or chicken with foil on the end of the legs, so that it doesn’t overcook. Never done it myself, but apparently it’s a thing, and not a disaster.
In the video posted above, there is no way for the soup to get hot, because it’s protected by the can. That also means that all the energy is being pumped into the circulating currents in the can – no wonder it arcs!
I’ve just bought a new microwave and actually scanned through the manual for once. I’ve always followed the ‘no metal in the microwave’ rule, so I was quite surprised to find the manual suggesting wrapping thinner parts of things like meat in aluminium foil to stop it burning before the rest of the food is cooked. There’s even a section on safely using foil in the microwave. So not just a thing, but a recommended by manufacturers thing.
OB
Well, that is not a “Can of Soup”, that is an Empty Soup Can, Lol
Back 40> years back my Pa told us that putting a metal cup or bowl in a microwave oven could be a problem if there was trapped water in a seam such as a rolled and sealed base or lip.
He did a lot of reading on anything new and toyed with those heath kit projects a lot.
One other thing he said was popping popcorn is hard on the Microwaves Gizzard(my word), but Nuking popcorn at work along with about 20 other co-workers didn’t appear to be hard on that oven.
So remembering Pa’s many words of wisdom i would get a kick out of the guys that would get all bent out of shape when i put my can of soup in.
Then there are grapes. One of my nephews put grapes in my microwave one and caused some problems.
Gilded dinnerware can catch you off-guard. I put a Christmas plate with gold edging in the microwave once. Ever put a CD in a microwave? Same thing: the thin layer of gold edging on the plate was destroyed, criss-crossed by a jagged mesh of arc trails where the metal had been blown away. Oops.
I’m old enough to remember Barbara Hale (of Perry Mason fame) pitching for Amana Radar Ranges on television. She would put frozen TV dinners in the Range with portions protected with foil.
I once owned an Amana Radar Range Cooking Guide. This was the instructional booklet that came with a Range. It specifically permitted using foil as a blanket, as mentioned by lingyi.
Of course that was 40 years ago. Modern units are probably different and I would certainly read the owners guide to see if it was still permitted.
I remember watching a PBS cooking show in the late 1980s that had a segment on using aluminum foil safely in a microwave oven. Complete with demonstrations.
The upshot seemed to be that the surface area of the food had to be much larger than the surface are of the food. No wrapping a potato in a foil jacket and trying to bake a potato in a microwave the way you would in a regular ol’ oven.
Put the can in unopened. Problem solved.
Do not do that. I was just kidding.
My son had a microwave that came with a metal rack. But it didn’t have sharp edges and there was no arcing.
Our microwave-convection metal rack does not spark. I regularly leave a metal spoon in a non-metal container of food being nuked. No forks because arcing. All the gold foil boiled off our decorated Celtic cup so it gets nuked for coffee without regret. But anything microwaved for the first time gets watched for sparks.