White countertop microwave on a kitchen counter

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Microwave interior paint peeling, chipped or rusted (when to stop using it)

The cavity coating protects the steel; once bare metal is exposed it can rust and act as an arcing point, and flaking paint can fall into food. Small, isolated chips on an otherwise sound cavity can sometimes be touched up with a coating made for microwave cavities, fully cured before use. Widespread peeling, rust that has pitted or holed the metal, or any damage to the door, choke or seal area means the oven should be retired. Never use ordinary paint.

Cross-checked ~30 min easyBrands: All

Before you start

Unplug the microwave before inspecting or repairing the cavity
Do not open the outer cabinet: the high-voltage capacitor can hold a dangerous charge after unplugging (see component-hv-capacitor-bleeder)
Use only paint labeled for microwave cavities; ordinary paint can burn, arc or give off fumes
Do not run the microwave until any touch-up has fully cured
Rust that holes the metal, or damage to the door or door seal area, means stop using the oven

Diagnostic steps

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