TL;DR
Lift out the glass turntable and the roller ring and wash both in the sink -- the roller ring is the part almost nobody washes, and dried spills in its wheels are why a turntable grinds and sticks. Steam the cavity soft with a bowl of water before wiping. Never scrub, soak, or remove the thin tan panel on the side wall: that is the mica waveguide cover, and damaging it causes arcing.
Three parts, one order
A microwave has a glass plate, a roller ring underneath it, and the cavity itself. Cleaning them in that order -- plate, ring, cavity -- keeps you from wiping a clean wall and then dropping a dirty ring back on it.
The plate and ring are dishwasher-friendly on most models. The cavity is a wipe job.
The one part with a genuine restriction is the waveguide cover, and it is worth knowing what it is before you start. General appliance rules live in the small appliance cleaning guide.
How do you clean a microwave turntable ring?
Lift out the glass plate, then lift out the plastic roller ring underneath it. Wash the ring in warm soapy water with an old toothbrush, working around each wheel and the hub so dried food comes out of the axles. Rinse, dry it, and wipe the recessed track in the cavity floor where it sits before putting it back.
The wheels are the whole point. Food that dries in a wheel axle is what makes a turntable grind, stall, or rotate unevenly.
Most roller rings are top-rack dishwasher safe, but the axles still need a brush, because a dishwasher jet does not reach inside them.
The glass plate and thermal shock
Let a hot glass turntable cool before it touches cold water. Tempered glass can crack from thermal shock, and a cracked plate is a replacement part rather than a repair.
Wash it like any dish, in warm soapy water or on the bottom rack of a dishwasher if the manual allows.
Dry it and set it back on a clean, dry roller ring. A plate that wobbles usually means the ring is dirty or a wheel is missing, not that the plate is warped.
Steam the cavity instead of scrubbing
Put a microwave-safe bowl with a cup or two of water and a few slices of lemon inside, and run it on high for three to five minutes. Let it stand with the door closed for a few more minutes so the steam condenses on the walls, then wipe the cavity with a soft cloth.
Steam does the loosening. Splatter that would take a scouring pad wipes off with a cloth after five minutes of steam.
Follow with a cloth wrung out in warm soapy water, then a clean damp cloth, then dry. This is the same soften-first principle behind cleaning a toaster oven interior, rack, and crumb tray.
The waveguide cover: do not touch it
On the right or left interior wall there is usually a thin rectangular panel, tan or beige, made of mica. It covers the opening where microwave energy enters the cavity, and it is meant to be there.
Wipe it very gently with a barely damp cloth and nothing more. Do not scrub it, do not soak it, do not use abrasives on it, and do not remove it.
Mica is soft and slightly porous. A damaged, saturated, or missing cover causes arcing -- visible sparks inside the cavity -- and that is a repair, not a cleaning problem. If yours is charred, pitted, or has burn marks, stop using the microwave and have the cover replaced.
Source: U.S. Food and Drug Administration guidance on microwave oven safety
What not to use in a microwave
No abrasive powders, no scouring pads, no steel wool, and no oven cleaner. All of them damage the cavity's painted or enamel finish, and a chipped interior finish can lead to rust and arcing.
Chlorine bleach is unnecessary here and it can pit a stainless interior. Never mix bleach with vinegar, ammonia, or rubbing alcohol in any container, because those combinations release toxic gases.
Do not spray any cleaner directly into the cavity. Overspray gets into the vent slots and behind the waveguide cover, which is exactly where liquid should not be.
The door, the seal, and the vents
The door seal and the flat surface it presses against are a safety-relevant area. Wipe them with a soapy cloth and dry them, and keep food debris out of the sealing surface.
Do not use abrasives on the door seal, and do not bend or pry at the latch. If a door does not close cleanly, will not latch, or the seal is damaged, have it serviced rather than working around it.
Vent slots on the top or back collect greasy dust. Wipe them or use a dry brush. Over-the-range models also have a grease filter underneath that needs washing, which behaves like the filter on an air fryer heating element and grease drawer.
Smells, stains, and a schedule worth keeping
For lingering odor, run the lemon-water steam cycle again and leave the door open for an hour afterward. An open box of baking soda inside overnight absorbs what remains.
Yellowed or stained interior paint from repeated splatter usually will not come back to white, and abrasives that might lift it would damage the finish. Living with the stain is safer than scouring it.
Grease that has burned onto the ceiling of the cavity takes two or three steam-and-wipe rounds. Patience beats force. The same is true of a warming drawer, its liner, and vent slots.
Wipe splatter the day it happens -- that is the whole trick. Steam-clean the cavity weekly with regular use. Wash the plate and roller ring weekly or whenever the turntable sounds rough.
Check the waveguide cover, the door seal, and the vents monthly.
Cleaning removes soil so food does not taste like the last thing that exploded in there, and it keeps the turntable turning. It does not sanitize the kitchen and does not prevent anything. If the kitchen needs more than the microwave does, house cleaning services can take the room.
FAQ
Can you put a microwave turntable ring in the dishwasher?
Most roller rings are top-rack dishwasher safe, and the glass plate is usually dishwasher safe too, but check the manual. Even after a dishwasher cycle, brush the ring's wheel axles by hand, because jets do not reach inside them and dried food there is what makes a turntable grind.
What is the tan panel inside my microwave?
That is the mica waveguide cover, and it shields the opening where microwave energy enters the cavity. Wipe it very gently with a barely damp cloth only. Never scrub, soak, or remove it. If it is charred, pitted, or missing, stop using the microwave and have it replaced.
Why is my microwave turntable not turning smoothly?
Dried food in the roller ring's wheel axles is the usual cause. Lift out the plate and ring, brush each wheel and hub with an old toothbrush in warm soapy water, and wipe the track in the cavity floor. A missing or broken wheel will also cause grinding and needs a replacement ring.
How do you clean a microwave with steam?
Put a microwave-safe bowl with a cup or two of water and a few lemon slices inside and run it on high for three to five minutes. Let it stand with the door closed a few more minutes, then wipe the walls with a soft cloth. The steam loosens splatter so no scrubbing is needed.
Can you use vinegar to clean a microwave?
Yes. A bowl of water with a splash of white vinegar steams well and helps with odor, though lemon smells better to most people. Rinse the cavity with a plain damp cloth afterward. Never mix vinegar with bleach or any chlorine product, because that reaction releases chlorine gas.
What causes sparks inside a microwave?
Metal in the cavity is one cause, and a damaged, food-soaked, or missing mica waveguide cover is another. Chipped interior paint that has allowed rust to form can also arc. Stop using the microwave until the cause is identified, and have the waveguide cover replaced if it is damaged.
Microwave splatter is the kind of mess that quietly coats the cabinet above it and the wall behind it too. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.