Can you microwave a can?

A steel or aluminium can reflects microwaves, so the contents heat very little while the can itself picks up energy at its rim and seams and sparks. A sealed can is worse: any heating raises internal pressure with nowhere for steam to go. Even an opened can with the lid removed still shields the contents and arcs at the cut edge, which is sharp and thin — the worst possible geometry for charge concentration.

What goes wrong

• Arcing at the seam and cut rim damages the oven
• A sealed can builds pressure and can rupture
• Contents stay cold, which invites longer and longer runs

What to do instead

• Empty the can into a bowl or mug first
• Heat soup on the stove if it needs to reach a proper simmer

Other "can you microwave" questions

• Can you microwave styrofoam? It depends — Only if the container is labeled microwave-safe, and most takeout foam is not.
• Can you microwave aluminum foil? No — No — foil reflects microwaves and the edges arc, which can start a fire.
• Can you microwave plastic containers? It depends — Only ones labeled microwave-safe — cold-storage tubs are not among them.
• Can you microwave eggs? It depends — Beaten or pricked eggs, yes. A whole egg in its shell will explode.
• Can you microwave Tupperware? It depends — Yes, if that specific piece carries the microwave-safe symbol on its base.
• Can you microwave paper plates? It depends — Plain white paper plates are fine; anything with metallic trim or a foam layer is not.
• Can you microwave metal? No — No — metal reflects microwaves, arcs at edges, and can damage the oven or start a fire.
• Can you microwave breast milk? No — No — microwaves create hot spots that scald a baby even when the bottle feels cool.
• Can you microwave takeout containers? It depends — Only if the container is marked microwave-safe — most are not, and metal-handled ones never are.
• Can you microwave cardboard? It depends — Plain dry cardboard is usually fine briefly; anything with glue, staples, wax or foil is not.
• Can you microwave glass? It depends — Yes for ordinary heatproof glass; no for leaded crystal, and never straight from the freezer.
• Can you microwave water? It depends — Yes, but very clean water can superheat and erupt when you move the cup.