Colour fastness to laundering
In general, when you buy a textile product, you expect it to retain its colour well. Colours that are permanent are considered to be colourfast. The colour of a textile product can be influenced by, among other things, wear and use, cleaning, exposure to sunlight, bleaching agents, perspiration and so on. The end use of a textile product is therefore an important determining factor in the colouring process, because the colour must be colourfast under the conditions in which it will be used.
For textile products that are washed, colour fastness to laundering is important and one of the most commonly used methods is explained below.
EN ISO 105-C06
The determination of colour fastness to laundering is often carried out in accordance with EN ISO 105-C06. This is used to determine the colour fastness in domestic and commercial laundering in daily use.
Colour change and bleeding
The influence of washing has two aspects, namely the degree of change of the original colour and the release of the colour on white textiles that are washed at the same time. This staining is called 'bleeding'. For the white textile a so-called multifiber, a strip of woven fabric with different compositions is used. Both the colour change and the bleeding are determined quantitatively by comparing it visually with a standard grey scale with a score of 1 to 5. Where 5 stands for no colour change or bleeding and 1 for very strong colour change or bleeding.
The determination of colour fastness to laundering is carried out in a detergent solution with a volume of 50 to 150 ml and the use or non-use of a bleaching agent depending on the method and at a temperature between 40 °C and 95 °C. In addition to the test simulating a washing cycle, there is a multiple test which corresponds to the effect of multiple washing cycles. For the mechanical washing effect, small steel balls are used which rotate with the test.
After washing, the sample is rinsed and dried together with the multiple fiber. After this the colour change and bleeding can be determined. This can be done visually or instrumentally, as previously mentioned, using a suitable spectrophotometer.
Some alternative methods offered by VTC in addition to EN ISO 105-C06:
- EN ISO 105-C08 for the determination of colour fastness in household and industrial laundering using phosphate-free detergents with a low-temperature bleaching activator.
- EN ISO 105-C10 for the determination of the colour fastness in washing with soap or soap and soda.
- EN ISO 105-C12 for the determination of colour fastness in industrial laundering.