Microwaves are a quick and convenient way to heat food, but not everything belongs inside one. Using the wrong containers or heating certain items incorrectly can damage your appliance, affect food quality, or create a safety risk.
Here’s a simple, practical guide to what you should avoid microwaving and how to stay safe at home.
Avoid Anything Containing Metal
Metal and microwaves do not mix. Even small amounts can cause sparks and potentially lead to a safety risk.
This includes:
- Aluminium foil and foil trays
- Cutlery or metal utensils
- Plates or mugs with metallic trim or decoration
- Takeaway containers with metal handles or staples
If food arrives in metal packaging, always transfer it to a microwave-safe dish before reheating.
Read our blog: Microwaves: How to solve heating issues
Be Careful with Plastics and Disposable Containers
Not all plastics are designed for microwave use. Some can melt, warp, or release chemicals when heated.
Avoid:
- Plastic containers without a “microwave-safe” label
- Polystyrene or foam takeaway boxes
- Old, cracked, or discoloured plastic containers
When in doubt, use glass or plain ceramic, which are safer and heat food more evenly.
Don’t Microwave Sealed or Pressurised Items
Items that trap steam can burst or explode when heated in the microwave.
This includes:
- Eggs in their shells
- Sealed containers or tightly covered lids
- Food with thick skins that haven’t been pierced
Always allow steam to escape and follow recommended heating instructions.
Read our Blog: Preventing condensation build-up in microwaves
Avoid Items That Can Spark or Fume
Some foods and materials can spark, smoke, or release strong fumes when microwaved.
Examples include:
- Foods with high sugar or skin tension (such as grapes)
- Brown paper bags
- Hot chillies or peppers, which can release irritating vapours
These can damage your microwave or cause discomfort when the door is opened.
Never Run the Microwave Empty
A microwave should never be switched on without food or liquid inside.
Without anything to absorb the energy, the microwaves can reflect and damage the internal components of the appliance.
Check for Microwave-Safe Symbols
Before putting anything in the microwave, always check the base of the container or dish.
Look for:
- The words “Microwave Safe”
- A microwave icon with wavy lines
- A dish symbol with waves above it
If there’s no label, it’s safest to assume the item is not microwave-safe.
Keep on Top of Microwave Cleaning
Regular cleaning isn’t just about keeping your microwave looking good it also helps it work properly and safely.
Food splashes and grease can build up inside over time, affecting how evenly your microwave heats and, in some cases, causing unpleasant smells or even smoke.
Key Areas to Clean Regularly
- Interior walls and ceiling: Wipe these down to remove food residue and grease.
- Turntable and roller ring: Remove and wash these to ensure food rotates properly.
- Door and seals: Keep clean so the door closes correctly and safely.
- Waveguide cover (usually a small panel on the side wall): Gently wipe this area to prevent grease and food particles from building up.
Do not remove or damage the cover, as it protects key microwave components.
Always refer to the user manual.
Read our full Blog: Microwave Maintenance: Caring & Cleaning
Final Thoughts
Using your microwave safely doesn’t have to be complicated. By avoiding metal, unsuitable plastics, sealed items and unlabelled containers, you can protect your appliance and enjoy safer, better-heated food.
A quick check before heating can help prevent accidents, mess, and unnecessary replacements.
If you’re unsure it’s always better to change the container than take the risk.
View the full range of Microwaves here