New consumer trends have created the need for packaging that can be reused.
The aim of the test is to assess the physical resistance of a plastic material to washing in a domestic dishwasher by simulating the use that a consumer might make of an item intended to be reusable at home.
What is resistance testing?
In our laboratories, we perform testing in accordance with the standard UNE 53928. In this test, accredited by ENAC, we subject plastic samples to several successive washing cycles under the conditions determined by the standard regarding water hardness, washing time and temperature, type and quantity of detergent, type and quantity of rinse aid and drying time.
The minimum number of washes to comply with this standard is five cycles and the maximum number of washes is at the manufacturer’s discretion. To determine the maximum number of washes, you can test directly the number indicated by the manufacturer to see if the sample complies or not, or you can assess the sample every “X” cycles to see when the product no longer meets the requirements of the standard and thus determine more accurately the maximum number of washing cycles that the product can withstand.
To verify the integrity of the material, a visual inspection is carried out after the washes by two qualified inspectors, who compare the tested samples with standard or reference samples, i.e. original samples that have not been washed. Each inspector independently records the visible changes observed.
This visual check consists of looking for possible changes in any of the following properties:
- Presence of resistant deposits and iridescent layers.
- Cracking, swelling, deformation, delamination and any other defects that may arise.
The marking of the maximum number of washing cycles the material has been shown to withstand may be included on the product itself or on its labelling or packaging using the pictogram shown in the standard.
What this test demonstrates is that the material physically withstands an exact number of washing cycles and can therefore be reused by the consumer without changing its original condition or characteristics. In order to demonstrate that a reusable plastic material is safe for the consumer, migration testing has to be carried out in accordance with Regulation (EU) No 10/2011.
Migration testing is mandatory before the dishwasher resistance test, but after the wash cycles it is actually recommended as the legislation does not indicate that it is mandatory at that time.