Do not repurpose a cold-storage yogurt tub as microwave cookware. Manufacturer-authorized use matters more than shape or stiffness. Read the lid and film instructions separately too.
Cold storage and heating are different uses
Canada's Healthy Home Guide explains that single-use yogurt or margarine tubs can warp or melt during heating. Having contained food for sale does not establish suitability for cooking.
Check the body and lid separately
Find microwave-use wording and its conditions. A suitable body does not automatically authorize the lid or its vent position. A recycling resin number or the word plastic alone does not establish the intended use.
Do not repeatedly reuse a single-use tray
Health Canada notes that microwave-meal and take-out trays are generally designed for one use. An original package intended for one heating differs from a reusable storage-and-cooking container.
Transfer when the instructions are unclear
Use a suitable container labelled for microwaving if authorization cannot be confirmed or the container is damaged. Follow food-contact wrap and steam-vent directions. Container suitability and sufficient food heating are separate checks.
Turn observations into a decision
| Observation or wording | Meaning and limit | Next action |
|---|---|---|
| Body has microwave directions; lid unclear | Body permission does not authorize lid or film | Check lid and steam-vent directions separately |
| Washing a single-use heating tray for reuse | One heating and repeated use are different purposes | Use another container authorized for repeated heating |
| Only a recycling number; no heating direction | Material classification sets no heating time or temperature | Transfer to a confirmed microwave-use container |
A worked example
Fictional A gives directions on the body but none on its lid. Do not copy 'body permitted' into the lid field; verify it separately. B is a tray meant for one heating of the original meal. Choose a container with confirmed reuse permission for a second cooking. Suitable containment still does not establish adequate food heating.
Official sources checked
Official sources checked 12 October 2026. AI assisted writing and translation; numbers, scope and sentence meaning were reviewed repeatedly. No individual product test or personal diagnosis or prescription is provided.