Washing machines should not only deliver good removal of stains, but also take care of the garments. Mechanical action produced by the washing machine has a twofold impact: It supports the removal of stains, but it also influences the structure of the textiles negatively and is, therefore, critical to textile care. Most washing machines are currently assessed by consumer organisations and political regulations, such as energy labelling, just for their washing properties. However, a long programme may provide a good washing performance, but might also damage the textiles more than a shorter programme. Test specimens assessing the mechanical impact are well known and published, for example, IEC PAS 62473:2007, however, they are rarely used. Reasons may be poor knowledge about their effectiveness in assessing the mechanical action and their reaction to different washing conditions, for example, load size, temperature and duration of the washing programme. It was the task of this study to verify this relationship and confirm that the thread removal fabric, as specified in IEC PAS 62473:2007, adds additional information to the assessment of a washing process. As a result of a wide variation of washing parameters, it could be shown that this test fabric is almost independent of the washing temperature, but shows a clear correlation with the load size and the length of the washing process. The thread removal specimens add valuable additional information concerning a relevant parameter of the washing process.

Since the washing performance of household washing machines must comply with certain limit values, like the ecodesign requirements in Europe, the method of washing performance evaluation is crucial. Today, the washing performance is defined as an overall washing performance in IEC 60456:2010, constituting an calculation of the average sum of reflectance values of five different stain monitors. As a result, the different washing characteristics of each individual stain are totally neglected. This study investigates how the washing cycle affects the individual stains, when washing temperature, washing time and load size are varied systematically. The results show individual stains contribute differently to the overall washing performance. For a proper assessment of the washing performance, the individual stains’ contributions to the overall washing performance are required to be considered. A supplement of temperature sensitive stain monitors is suggested. E.g., as tea has a crucial contribution at higher temperature, this stain should have a higher influence in washing performance assessment when good bleaching or hygiene performance is requested.