This method is intended for accessing the resistance of the colour of textiles to the action of daylight.
Principle: A specimen of the textile is exposed to the light from a Xenon arc lamp under prescribed conditions, along with eight dyed wool standards. The fastness is assessed by compared the fading of the textile with that of the standards.
Apparatus and Materials:
- Blue standards
- Humidity Test Control Fabric
- Light fastness test apparatus containing a Xenon arc lamp (5500-6500°K), a light filter, heat filters and a black panel thermometer
- Grey Scale for assessing change in colour
Procedure:
Mount the specimen under test and the blue standards on a card, and mask the middle one-third (AB) of the test specimen and blue standards with opaque cover as shown in the following figure.
Expose the test specimen and blue standards to the xenon arc light. Cover one-third of the test specimen and blue standards with an additional opaque cover. After 20 hours, check the effect of light by removing the cover and inspect the specimen. Compare the test specimen with Reference number 4.
Results and Assessment:
Comparing the visual contrast between the exposed and unexposed portions of the specimen under test with the corresponding portions of the blue standard 4 in standard viewing condition. We can see that the performance of the specimen is quite satisfactory as it scored a rating of grey scale 5, while the blue standard 4 has faded to grey scale 4-5.
Conclusion and discussion:
In this test, there are certain factors that would affect the testing results. Inside the exposure chamber, a light filter is placed between the light source and the samples so that the ultra violet spectrum is steadily reduced. It must be well ventilated.
While for the light box, the purpose of it is to provide light and standardize the simulated light for evaluating results. The D65 light used in the light box is to