What Actually Happens When You Put Metal in a Microwave

The rule is vitamin a simple as it is omnipresent : do n’t stick aluminum foil in the microwave if you do n’t want to have to buy a raw microwave. Everybody knows that, right ? But, turns out, that old proverb might be wrong. ad

The second coming of electric refrigeration was a revolution in american english gastronomy that made a huge splash in the first gear two decades of the twentieth hundred. But it barely holds a candle to the changes wrought by the microwave oven in the century ‘s final two decades. nowadays, more than 90 percentage of american homes have at least one microwave. But, for a bunch of us, the engineering behind the humming box that reheats our leftover burrito might angstrom well be magic .

How Microwaves Work

Microwaves work thanks to magnetrons. This engineering, primitively designed for military radar systems, generates very short, high frequency radio waves from standard AC current—usually around 2.5 gigahertz. That frequency is just right for being absorbed by water system, fatness, and sugar molecules within constituent matter. This extra energy causes them to vibrate at identical high speeds, which in turn generates waste inflame that actually cooks the food. reverse to democratic belief, microwaves do n’t cook food from the inside out. Their radio waves actually merely penetrate about an column inch and a half into foods. It ‘s the conductive properties of the meat and establish matter that heats it all the way through. The outside parts precisely carry the heat inwardly. That ‘s why it ‘s better to cook large pieces of kernel at dilute power for longer periods—you ensure that the kernel cooks all the way through without overdoing the out bits. And since microwaves do n’t actually heat the air out around the food, as conventional ovens would, food does n’t get crisp aureate anything. Which is occasionally a bless, but most frequently a curse .

Metal in a Microwave

inorganic materials are a different matter entirely. Non-reactive, non-metal vessels of ceramic, plastic, or field glass do not absorb radio waves at that frequency and consequently, do n’t heat up very much in the microwave. Metal, on the other hand, actually reflects microwave energy. That ‘s why the inside of every microwave is basically a guarantee alloy box—they keep microwaves from spreading out across the kitchen and cooking your insides from across the room. now things get a little eldritch. It turns out that any flat metallic sheet—the dense the better ( and we ‘ll get to why in a moment ) —can be used safely in the microwave because they act just like the flat metal walls : they reflect microwaves. A sheet of flat alloy can actually be used to shield parts of your dinner to prevent them from overcooking since they would prevent the microwave energy from actually striking the food. And when placed under, say, a DiGiorno ‘s frozen pizza, a two-dimensional sheet of metallic element can actually help brown and crisp foods by reflecting extra energy against the bottom of the food .

Watch for Flying Sparks

sometimes the electromagnetic field within the microwave can get a small mix up and generate humble bow of electric discharge. This can be caused by innocent items like carrots ( when grown in mineral rich territory ) and hot dogs ( when the salt and additives are n’t properly desegregate ). More control spark occurs with the gold paint on your dainty dishes and forget flex ties. But a big hunk of crook aluminum thwart like on a adult box of wine spells blink of an eye appliance death. ad

Unlike the sturdy walls of a microwave, small, flimsy, and pointed pieces of foil can not withstand the run of microwave energy over them and quickly hotness until they ignite. Any thin, crinkled edges allow stream to run along them, arcing against the microwaves metal walls and setting fire to your meal. If caught immediately, you can avoid badly damaging your microwave by plainly removing the offending snatch of alloy. however elongated microwave of metallic element ( or wadding up an entire roll and tossing it in a nuker ) will likely cause irreparable damage to the appliance and probably set other parts your kitchen on fire. ad

As such, follow the USDA ‘s advice :

  • Use new, smooth foil only. Wrinkled foil can cause arcing (sparks).
  • Cover no more than 1/4 of the food with foil.
  • Shape the foil smoothly to the food so no edges stick out.
  • It makes no difference which side of foil (shiny or dull) is facing out.
  • Do not place the foil closer than one inch from the oven walls.
  • If the microwave oven has metal shelves OR a metal turntable, don’t microwave food in foil containers or metal pans, and don’t let foil used for shielding touch or be close to the shelves or turntable.
  • If you see arcing (sparks), immediately remove the foil shielding; transfer frozen food from foil container to a microwave-safe utensil.


so ampere long as you keep the metal bland, thick, and covering ampere little floor space as possible, you will be able to throw microwave shade on your epicure knight bachelor chow. [ USDA – How Stuff Works – CERN ] ad