Whether you can put aluminum foil in the microwave depends on the oven's maker, so I'd read your own manual before anything else. Some makers allow small, smooth pieces and others rule foil out. Crumpled foil, sharp edges or foil near the walls can throw sparks, which manuals call arcing.
A microwave oven is a cooking appliance that heats food with microwave energy, which the water in food absorbs. Metal reflects that energy instead.
I'm Michael Ruhr, and I write from Duncan for Merit Home Furniture. Merit's microwaves and other appliances on Vancouver Island are carried at our Campbell River and Port Alberni stores, so I've gone to their makers' own manuals rather than guessing. Two Danby models on our listings answer the foil question differently, which shows how model-specific the rule is.
Can you put aluminum foil in the microwave?
Aluminum foil can go in a microwave only when the oven's maker allows it, and then only as small, flat pieces. Whirlpool's product help says aluminum foil for shielding may be used, as long as it doesn't touch the cavity walls, ceiling or floor, or another metal object. Shielding means covering a thin or delicate part of the food so it doesn't overcook while the rest heats.
Government food-safety advice is stricter than the makers. The USDA's Food Safety and Inspection Service sheet on cooking safely in the microwave, revised June 2011, says never to use aluminum foil in the microwave oven. The US Food and Drug Administration agrees that, generally, metal pans or aluminum foil shouldn't be used, because reflected microwaves can cook food unevenly and may damage the oven.
Health Canada's page on microwave ovens doesn't mention foil at all. Its first safety step is to follow the maker's operating procedures and safety precautions, which brings the question back to the manual. If the manual allows shielding, a narrow strip used as described is within the maker's terms. If it says no, or the manual is long gone, I'd leave foil out entirely.
Aluminum foil rules from four microwave makers
The four makers below all have microwaves on Merit's listings, and they don't agree. Prices are Merit's, before applicable taxes, as listed on November 1, 2026.
| Microwave and price | What its maker says about foil |
|---|---|
| Danby 1.1 cu. ft. countertop, $139.99 | Its 2024 manual files aluminum foil under "not recommended", since foil can cause arcing and damage the microwave. Carried at Campbell River and Port Alberni. |
| Danby Designer 0.7 cu. ft., $134.99 | "Limited use": narrow strips over exposed areas, kept at least 1 inch (2.6 cm) from the inside of the oven. Carried at Port Alberni. |
| Whirlpool Low Profile over-the-range, $529.99 | Whirlpool's help page allows foil for shielding if it touches no wall, ceiling, floor or other metal. Carried at Campbell River and Port Alberni. |
| Midea 1.2 cu. ft. Slim over-the-range, $399.99 | Midea Canada's guide says foil only if the manual allows it, at least 1 inch from all interior surfaces, on no more than a quarter of the dish. Carried at Campbell River and Port Alberni. |
The two Danby rows come from each model's own manual. The Whirlpool and Midea rows come from brand-wide help pages rather than these exact models, so the booklet in the box has the final word on those two. Our Amana 30 in. over-the-range microwave, $349.99, falls under the same Whirlpool-family help text, which Amana publishes word for word on its own site.
Can you microwave aluminum foil containers and wrappers?
Aluminum foil containers and foil wrappers are where the makers line up against it. Whirlpool's help page lists foil liners such as sandwich wrappers among the things to keep out, along with twist ties, skewers and staples. Midea Canada says a sandwich wrapped in foil should come out of the foil first. A foil takeout tray is usually single use as well, and Health Canada's microwave tips say not to reuse trays or containers from microwave dinners or takeout.
If foil goes in by accident and flashes, Danby's manual says to stop the oven and take out any metal or paper towels. Whirlpool warns that arcing, a blue flash of light, can damage the oven, so it's worth a look inside afterwards. Health Canada says not to use an oven whose door is bent, warped or damaged, and noticeable damage to the door, hinges, latches or screen calls for a professional inspection.
Can you put aluminum foil in the microwave oven's convection mode?
A convection microwave adds a heating element, so it can bake like a small oven. Midea Canada says that in convection mode many models allow some metal trays or foil, as long as the manual says it's safe. Microwave mode is another matter, even in the same box. The manual for Danby's 1.0 cu. ft. 5-in-1 countertop microwave, $449.00 and carried at Port Alberni, says its metal grill rack shouldn't be used when running the microwave.
What not to put in the microwave, besides foil
The list of things not to put in a microwave is short, and most of it comes down to metal, fire or steam pressure. The table pulls it together from the Danby manuals, Whirlpool, Health Canada and the USDA.
| Keep out | Why, and who says so |
|---|---|
| Metal pans and gold or silver trim | Whirlpool lists metal cookware, gold, silver, pewter, and dishes with gold or silver trim or a metallic glaze. |
| Steel travel mugs | A stainless mug is metal, so the metal rule applies. Pour the coffee into a mug labelled microwave safe. |
| Unlabelled plastic | Health Canada says to use only glass or food-grade plastic labelled microwave safe, and nothing damaged, stained or smelly. |
| Margarine and takeout tubs | The USDA says one-time-use containers can warp or melt. |
| Brown paper and grocery bags | Danby calls paper bags a fire hazard, except popcorn bags made for the microwave. The USDA says never to use them. |
| Recycled paper towels and plates | Danby says recycled paper can contain metal and could ignite. |
| Eggs in the shell, sealed jars | Danby's manuals say whole eggs and closed glass jars can explode. |
Plastics get the most questions. Health Canada's page on bisphenol A (BPA) says to use only plastic wrap labelled microwave safe, alongside the container rule in the table. On BPA itself, its 2008 risk assessment found most Canadians had low to very low exposure that doesn't pose a health risk. To test a dish with no label, Danby's manual suggests heating it empty on high for 30 seconds. If it comes out very hot, don't use it.
Is it safe to microwave parchment paper?
Parchment paper is on the safe list. The USDA sheet names microwave plastic wraps, wax paper, cooking bags, parchment paper and white microwave-safe paper towels as safe to use. It adds that plastic wrap shouldn't touch the food, and Danby suggests wax paper as a cover against splatter, so there's less to do when cleaning the microwave.
Can a paper takeout box go in the microwave?
A plain paper takeout box, like a fried chicken box, falls under Danby's rule for paper plates and cups: short heating at low temperatures, and no recycled paper. Check it for metal first, such as a wire handle, staples or a foil lining. Health Canada says takeout containers are usually designed for one-time use, so a plate is the safer dish for reheating.
Why grapes spark in a microwave
Grapes spark because two grape-sized spheres of water focus microwave energy into a hotspot, strong enough to make plasma, a glowing electrically charged gas. That's the finding of a 2019 paper in the Proceedings of the National Academy of Sciences by physicists at Trent University and Concordia University. They called the sparking grape an Internet parlour trick that had gone poorly explained for over two decades. I'd keep grapes, whole or cut, out of the microwave.
Superheated water and other microwave burns
Superheated water is water heated past its boiling point without bubbling, and it can boil over all at once when a spoon or a tea bag goes in. Danby's manuals set plain limits. They say not to heat any liquid for more than 2 minutes per cup, and to stir before and halfway through. After heating, they say to let the liquid stand in the microwave for 30 seconds before taking it out. They also warn against straight-sided containers with narrow necks. The FDA adds that putting instant coffee or sugar in before heating greatly reduces the risk.
Running a microwave with nothing in it is the other trap. The manual for Danby's 1.3 cu. ft. countertop microwave, $309.99 and carried at Port Alberni, says empty running raises the heat around the magnetron. That's the part that makes the microwaves, and the manual says the extra heat can damage the oven or cause a fire.
Steam from a covered dish burns too, and Danby says to open a heated container pointed away from your hands and face. For a burn that's more than minor, see a doctor. In BC, 8-1-1 (7-1-1 for the deaf and hard of hearing) reaches HealthLink BC, which can connect you with a health professional. HealthLink BC says a serious burn injury is a 9-1-1 call.
Three microwave myths: radiation, nutrients and standing time
The first microwave myth is that the oven leaks harmful radiation or makes food radioactive. Health Canada limits how much microwave energy any oven sold, leased or imported into Canada may leak. It says that limit is well below the level that would cause any known health effects. The FDA says the energy turns to heat as food absorbs it and doesn't make food radioactive.
The second myth is that microwaving kills nutrients. Harvard Health Publishing says some nutrients break down with heat from a microwave or a regular oven alike. The method that keeps the most, it says, cooks quickly, for the shortest time, in as little liquid as possible. Microwaving with a little water steams food, and Harvard says that keeps in more vitamins and minerals than almost any other method. Boiling does worse, since nutrients leach into the water.
The third myth is that standing time is optional. Food keeps cooking for a few minutes after the microwave stops, Danby's manual says. Health Canada's microwave tips say standing time completes the cooking and spreads the heat. They also say to reheat leftovers to 74°C (165°F), checked with a digital food thermometer, because microwaves cook unevenly.
How often should you replace your microwave?
A microwave gets replaced on its condition, since none of the sources I checked gives a set number of years. Health Canada says not to use an oven whose door won't close or is bent, warped or damaged, and to hire qualified service technicians for repairs. Danby's manual adds a damaged cord or plug, an oven that isn't working properly, and one that has been dropped.
A repair is worth asking about while the warranty runs. The manual for our Danby 1.1 cu. ft. model sets out a 12-month warranty. In-home service only reaches homes near an authorized Danby depot. An oven 100 km or more from a service centre goes to the depot, with transport at the owner's cost. On the Island, it's worth asking where the nearest depot is before counting on a quick fix. Our guide to who repairs what under each maker's warranty has more on appliances, and for one bought from Merit, the claim starts with the maker or the Merit store.
An old microwave can be recycled for free in BC. Since January 1, 2025, small appliances go to Return-It Electronics depots across the province, with over 400 kinds covered, according to the Recycling Council of BC. If a new one is next, it helps to know the three types of microwave before you shop. Merit's 58 microwaves at Campbell River and Port Alberni come three ways: 38 over-the-range, 19 countertop and 1 built-in.
Before the first plate of leftovers goes into a new microwave, I'd read the cookware page of its manual, where foil, paper and plastic are listed together. A lost manual is rarely gone for good. Danby, for one, publishes its owner's manuals online as PDFs, so the model number on the oven is usually enough to find one.
Sources for the microwave figures
- Health Canada, Microwave ovens (page dated 2019-10-21), checked November 2026.
- Health Canada, Food safety tips for microwaves, checked November 2026.
- Health Canada, Bisphenol A (BPA), checked November 2026.
- USDA Food Safety and Inspection Service, Cooking Safely in the Microwave Oven (revised June 2011), checked November 2026.
- US Food and Drug Administration, Microwave Ovens (content current as of October 12, 2023), checked November 2026.
- Danby, owner's manual for DBMW1121BWW, DBMW1121BBB and DBMW1126BBS (2024), checked November 2026.
- Danby, owner's manual for the DDMW007501G1 0.7 cu. ft. microwave (2021), checked November 2026.
- Danby, owner's manual for the DBMW1361ABSS microwave (2026), checked November 2026.
- Danby, owner's manual for the DDMW1060BSS-6 5-in-1 microwave (2021), checked November 2026.
- Whirlpool product help, Using aluminum foil and metal in microwave, checked November 2026.
- Amana product help, Using aluminum foil and metal in microwave, checked November 2026.
- Midea Canada, Can you put aluminum foil in a microwave?, checked November 2026.
- Khattak HK, Bianucci P and Slepkov AD, Linking plasma formation in grapes to microwave resonances of aqueous dimers, PNAS 116(10):4000-4005 (2019), abstract checked November 2026.
- Harvard Health Publishing, Microwave cooking and nutrition (August 17, 2021), checked November 2026.
- HealthLink BC, Determining the Seriousness of a Burn (current as of March 22, 2023), checked November 2026.
- Recycling Council of British Columbia, Where can I take my microwave for recycling?, checked November 2026.
- Merit Home Furniture's microwave listings, prices and store availability, read November 1, 2026.
Microwaves at Merit's Campbell River and Port Alberni stores
Merit's microwaves are carried at two of our four Island showrooms, so from Duncan I'd point you up-Island for one. It's worth calling ahead to ask which models are set up, and for an over-the-range or built-in model, check the opening against the microwave's own dimensions.
- The Campbell River store is at 1300 A Homewood Road, phone (250) 286-0868.
- The Port Alberni store is at 2935 Third Avenue, phone (250) 724-6644.
Delivery and installation are questions for the store itself, so it's worth raising them on that call. A microwave listed as a special order, with no store named, is ordered by phone at (250) 746-5527. Before that call, it's worth reading how deposits and returns work at Merit.
Call Campbell River, (250) 286-0868 or Port Alberni, (250) 724-6644
Every model is in the microwave collection, and everything we've written on kitchen and laundry appliances is gathered on one page.