Microwaved an enamel tin mug for 30 seconds - am I going to die?

August 12, 2022 6:35 AM

I did the unthinkable!

I bought an enamel camping mug yesterday and I think it is made of aluminum. Today I stupidly microwaved cold coffee for 30 seconds before remembering what the mug was made of.
So far, the microwave seems fine and the coffee tastes ok. But as we all know, isn't a microwave supposed to explode when you put metal inside it? Should I be worrying/doing anything to mitigate horrible explosions from happening?

posted by winterportage to Grab Bag (11 answers total)

You are fine. If the mug was going to catch fire it would have done so in the microwave, while it was being used.
posted by geoff. at 6:38 AM on August 12, 2022 [8 favorites]

If nothing bad has happened yet (you didn't see any sparks or hear any loud noises), you're fine. The metal in the mug was likely insulated by the enamel (obviously microwaves themselves contain lots of metal - it's just shielded appropriately. Still, avoid microwaving that mug going forward, obviously.
posted by mskyle at 6:41 AM on August 12, 2022 [3 favorites]

Yes, your first clue would have been seeing sparks fly from the metal in the mug while being zapped. Outside of that, nada.
posted by Melismata at 6:41 AM on August 12, 2022

The warning is because metal can potentially cause arcing that will damage the microwave; not that it will always do so. The size and shape of the item affects whether heat or electrical charge will build up enough to cause damage. It sounds like you lucked out -- the rounded and enameled cup was a structure where even though electrical induction might have occurred there wasn't enough of a build up to cause damage.
posted by AzraelBrown at 6:45 AM on August 12, 2022 [1 favorite]

Best answer: Pointy metal like a fork or crumpled aluminum foil is most likely to cause dangerous sparking in a microwave. Rounder objects like your mug CAN be fine. Definitely don’t microwave that mug (or any metal) regularly — you got lucky! But that’s a possible explanation for why nothing bad happened. Read more about metal & microwaves here.
posted by mekily at 6:50 AM on August 12, 2022 [2 favorites]

Yes, you’re going to die. But probably far in the future, and not because of a camping mug.
posted by kevinbelt at 7:24 AM on August 12, 2022 [21 favorites]

You'll be fine. enameled metal is covered by a layer of ceramic so it won't arc (or shouldn't, at least).
posted by kschang at 9:14 AM on August 12, 2022

2 things:

most modern microwaves have a metal rack that you can use in them, so the 'metal is dangerous in the microwave' is a bit outdated, but still generally true.

2nd thing: modern microwaves have an internal heat sensing capacitor that blows at a relatively low temperature to prevent fires. So you kill the microwave, but don't start a fire.
posted by The_Vegetables at 9:24 AM on August 12, 2022

I once microwaved a mug with a strip of what I thought was gold paint around the rim that turned out to be actual-metal enough to start sparking. It was loud, and not subtle.
posted by potrzebie at 11:55 AM on August 12, 2022 [1 favorite]

I once microwaved a mug with a strip of what I thought was gold paint around the rim that turned out to be actual-metal enough to start sparking.

We have some small plates that feature a glazed design on them. There must be some higher-than-usual level of metallic content in the glaze. I once reheated something (cookies? brownie?) on one of those plates. It was only in there for no more than 20 seconds but, when I grabbed the plate, I seared my fingers. Blistering burns. There was never a spark or crackle.

Those plates never go near the microwave now.
posted by Thorzdad at 12:23 PM on August 12, 2022 [1 favorite]

You actually can microwave metal, sometimes. I've microwaved frozen pot pies in aluminum pie pans and they haven't killed me or the microwave (yet).
posted by The corpse in the library at 6:25 PM on August 13, 2022