COLOUR FASTNESS – LIGHTFASTNESS TESTS
In the conditions of the standard ISO 105-B02
The test for colour fastness is one of the most common in textile (fabrics or yarns) to evaluate the lightfastness or fading of your natural colors. The samples are exposed to an artificial daylight during a specific time.
Samples of 8 blue standard textiles – scale of blues, the solidity of which in the light is known, are submitted to the same exposure for the same duration. The determination of the solidity in the light is made by comparison between the color loss of samples to be tested and those of the blue scale.
The lightfastness index ranges between 1 and 8, the highest value being 8.
Each new level means a solidity to light X 2 (e.g. twice more time to reach the same colour loss).