What is the test method of colour fastness to washing?

 

 

1. Preparation of Test Specimens: Textile samples, typically square or rectangular in shape, are prepared from the material to be tested. The samples may include both the dyed material and neighboring undyed material to assess color transfer. The size and number of specimens depend on the specific standard being followed.

 

1. Selection of Test Liquor: A test liquor is prepared, which usually consists of water, detergent, and other specified additives, such as bleaching agents or sequestering agents. The composition of the test liquor is determined by the standard being followed.

 

1. Loading of Test Specimens and Test Materials: The test specimens, along with specified reference materials, such as white cotton fabric or colorfastness monitoring fabrics, are placed into the washing machine or test equipment. The reference materials help to evaluate the color change of the test specimens.

 

1. Washing Procedure: The washing machine or test equipment is operated according to the specified parameters, which may include factors like temperature, time, agitation, and the number of washing cycles. The test specimens are subjected to repeated washing cycles, simulating domestic or industrial laundering conditions.

 

1. Drying and Evaluation: After the washing cycles are completed, the test specimens are removed, rinsed, and dried according to the specified procedure. The dried specimens are then evaluated for color change using a color assessment method, such as visual comparison against a set of color standards or using color measurement instruments.

 

1. Rating Color Fastness: The color change or transfer observed on the test specimens is compared to a standard rating scale, such as the ISO gray scale, to assign a color fastness rating. The rating indicates the degree of color change or transfer, with higher ratings indicating better color fastness and lower ratings indicating poorer color fastness.

 

It's important to note that different standards, such as ISO, AATCC (American Association of Textile Chemists and Colorists), or ASTM (American Society for Testing and Materials), may have specific variations in the test procedure and parameters. Manufacturers and testing laboratories typically follow the relevant standard applicable to their industry or country when conducting color fastness to washing tests.