Why do some metals work in the microwave?

[John Phoenix]

Why do some metals work in the microwave? Steel can be put in the microwave without the 'light show' as well as a few other metals. Whats the difference between these and aluminum?

[tomgwyther]

I'm not entirely sure as to the answer to this, but I think it has something to do with the proximity of a metal to another conductive object.

i.e the microwaves produce an electric charge in the metal object which then sparks to an Earth.

Thus a gold rimmed plate produces a light show as the electric charge in the gold tries to Earth to the surrounding ceramic glaze; where as a steel spoon either cannot Earth or is permanently Earthed.

 

Or it might have something to do with ferrous and non-ferrous metals.

 

My ignorance is showing in this matter though I would be interested in the real reasons for this phenomena.

[Dudde]

found a few links

 

Wiki-answers

TheWireUp

 

I actually found this by typing "why does metal spark in a microwave" and came up with some good results, just don't want to paste them all,

[swansont]

found a few links

 

Wiki-answers

TheWireUp

 

I actually found this by typing "why does metal spark in a microwave" and came up with some good results, just don't want to paste them all,

 

The second one is better IMO.

 

Short answer; EM radiation drives currents in a conductor, which give you potential differences. Sharp points are areas from which charge can more easily arc. Aluminum foil is more likely to have sharp points, since it crinkles easily.

[John Phoenix]

The second one is better IMO.

 

Short answer; EM radiation drives currents in a conductor, which give you potential differences. Sharp points are areas from which charge can more easily arc. Aluminum foil is more likely to have sharp points, since it crinkles easily.

 

I understand why some metals spark. I'm trying to understand why some do not. I can have one pot the same size and shape made of steel and one made of Aluminum. (not aluminum foil). Or if not a pot, a steel can that is store bought. Sometimes I don't even bother with a pot you see, I just open the can and stick it in the Nuke-o-Matic (microwave).

 

I worked for 20 years as an air conditioning and heating service man.. made a lot of duct work on a 9 foot break so I can tell the cans from aluminum easily.

 

I thought to ask this because microwave manufactures are insistent that you should never put any metal in the microwave. But to me this is silly because steel works well in one. oh, my microwave is Not the type designed for metals.. it's just a regular old microwave.

[StringJunky]

I understand why some metals spark. I'm trying to understand why some do not. I can have one pot the same size and shape made of steel and one made of Aluminum. (not aluminum foil). Or if not a pot, a steel can that is store bought. Sometimes I don't even bother with a pot you see, I just open the can and stick it in the Nuke-o-Matic (microwave).

 

I worked for 20 years as an air conditioning and heating service man.. made a lot of duct work on a 9 foot break so I can tell the cans from aluminum easily.

 

I thought to ask this because microwave manufactures are insistent that you should never put any metal in the microwave. But to me this is silly because steel works well in one. oh, my microwave is Not the type designed for metals.. it's just a regular old microwave.

 

Have you put a steel fork in the microwave...does this spark?

[Dudde]

I'm kind of in agreement with StringJunky on that one, have you tried something with an edge facing outward? My microwave is already broken or I'd try it personally

[StringJunky]

Expt1: I've just done 30 seconds each with a pair of scissors and a fork (S/Steel). The scissors did not spark and the fork did initially but stopped after 2 or 3 seconds. They were both quite hot to touch.

 

Expt2: I left the fork 'cooking' for five minutes to let it get really hot..on the basis that the electrons needed more energy to start arcing but it didn't happen. I laid it on top of a plastic thermos cup which melted where the fork was in contact...gives you an idea how hot I got it!

 

An aluminium ring-pull and small alumininium mitre block gave 'fireworks' almost immediately.

 

I think, probably, the main basis for the microwave manufacturers blanket recommendations against using metal objects is that there are too many shapes and combinations of metal types to recommend its use in them. They are playing safe.

 

Knowing what I know now about stainless steel, I still would not use it in a microwave because there maybe scenarios, I'm not aware of, that may be dangerous to the`appliance or myself.