Make sure your packaging withstands microwave heating.
The purpose of this test is to assess the suitability of a material for microwave use, i.e. to check its integrity and safe handling, always from the point of view of the physical resistance of the product to microwave heating.
What is resistance testing?
This test is performed in accordance with EN 15284, where the samples are exposed to two exposure periods, one short and the other longer. The shorter time corresponds to the use of items for heating food and beverages, and the longer time represents the use of materials for cooking food. These times are defined based on the power of the microwave. The test is carried out on empty samples (without food) as this is defined by the standard as the most unfavourable conditions with regard to the thermal stress that the product undergoes during heating.
After each exposure, the temperature reached by the materials is measured immediately, taking into account that all areas are measured, especially the thickest areas and handle-type areas where the product is held and where, after heating, there is a burn risk for the user when handling the product. The temperature for plastic products should not exceed 60°C.
Defects that may appear in the materials, such as colour changes, cracking and swelling, are also assessed visually. Methylene blue dye is used to highlight defects because they may not be visible to the naked eye.
If the material successfully passes only the short exposure time, its use is limited to one-off heating of food, whereas if the material successfully passes both short and long exposure times, it is suitable for heating and cooking food.
Most are made of polypropylene (PP) mainly because of their good physical resistance performance, although other materials can be used as long as they pass microwave resistance tests.