The light resistance of pigments refers to the resistance of pigments under light conditions, that is, whether pigments will change color, fade or fade after being exposed to light for a long time. Determining the light resistance of pigments usually requires a light resistance test.
Here are some common methods used to evaluate the light resistance of pigments:
Xe lamp (xenon lamp) exposure test: The pigment sample is placed under the Xe lamp light source and exposed for a long time. By observing and comparing the color change of the pigment before and after exposure, the light resistance of the pigment can be preliminarily evaluated.
Ultraviolet (UV) exposure testing: Pigment samples are exposed to a UV light source, usually using a UV lamp or UV accelerated aging equipment. By controlling the exposure time and intensity, the light resistance of pigments in sunlight or artificial light can be simulated. By observing the degree of discoloration and fading of pigments, their light resistance can be evaluated.
Natural Climate Exposure Test: Pigment samples are placed outdoors in exposed natural climatic conditions and experience the influence of natural factors such as sun exposure, rain exposure, and wind erosion. By continuously observing the color change and fading degree of pigments, its light resistance in the actual environment can be evaluated.
Photometric Measurement: Pigment samples are measured using a photometer to record the light reflectivity or transmittance of the pigment under different lighting conditions. By comparing the measurements, the light resistance of the pigment can be evaluated.
It should be noted that the evaluation of light resistance usually requires long-term testing and observation, and the results may be affected by many factors, such as pigment type, formula, concentration, substrate, etc. Therefore, for pigments in specific application fields, more detailed and rigorous light resistance tests may be required according to relevant standards and requirements to ensure their stability and durability in actual use.