Can you microwave a paper coffee cup?

A takeaway cup is paperboard with a thin polyethylene lining that keeps the drink in. That lining is rated for a hot drink poured into it once, not for a container being actively heated. Reheating can soften the lining and weaken the glued side seam, so the cup fails at the bottom. Some cups also have a metallic-ink logo or a foil-lined sleeve, which sparks. Pour the coffee into a mug; it takes five seconds and it will heat more evenly anyway.

What goes wrong

• The glued seam softens and the base drops out
• The polyethylene lining is not tested for active heating
• Metallic printing and foil sleeves arc

What to do instead

• Pour it into a ceramic mug
• Reheat coffee gently at 50 percent power to avoid boiling it bitter

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.