Color Fading Testing

Fading inspection mainly conducts scientific testing and analysis on the colour fastness to light testing of the textiles, weatherability fading testing of the plastic products, light resistance testing of the coatings and paints, light fastness testing of the printed matters, fading testing of the leather and synthetic leather, and light resistance rating of the dyes and pigments, objectively assessing the product quality grade and issuing a detailed test report, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Colour fastness to light testing of the textiles: Evaluates the ability of the colour of the textile to resist the fading under the simulated sunlight or artificial light source irradiation. This item is the key indicator for measuring the durability and quality grade of the textile, and is particularly applicable to the products exposed to the light environment for a long time, such as the outdoor textiles, curtains and automotive interiors.

Weatherability fading testing of the plastic products: Evaluates the degree of the surface colour change of the plastic materials (such as the PVC, ABS and polypropylene) under the combined action of the multiple factors such as the UV light, temperature and humidity. This is crucial for the life prediction and quality control of the products such as the automotive parts, outdoor building materials and household appliance shells.

Light resistance testing of the coatings and paints: Determines the colour and gloss changes, as well as the accompanying phenomena such as the chalking and cracking of the various coatings (such as the architectural coatings, industrial coatings and automotive paints) under the light action (especially the UV light). It is the core item for evaluating the colour retention and durability of the coatings.

Light fastness testing of the printed matters: Evaluates the persistence of the colours of the graphic and text of the ink printed matters (such as the posters, packaging, labels and art reproductions) under the light conditions. For the printed matters that need the long-term display or preservation, this item is the important basis for measuring their archival value and service life.

Fading testing of the leather and synthetic leather: Tests the colour change, migration or yellowing of the surface of the leather and artificial leather products under the light (especially the UV light) and climate aging action. It directly affects the appearance retention ability of the leather products such as the shoes, bags and furniture.

Light resistance rating of the dyes and pigments: The basic evaluation and grading of the light resistance of the dyes and pigments themselves, providing the scientific basis for their application selection in the industries such as the textile, plastics and coatings. The standard depth colour samples are usually adopted for the testing.

Testing Scope

Consumer goods field: Covering the daily consumer goods such as the garments, shoes and hats, home textiles, toys, stationery and sports goods. The ability to resist the colour fading during use, cleaning, especially the outdoor drying or storage is tested, ensuring that the appearance persistence of the product meets the expectations of the consumers.

Industrial and building materials field: Including the automotive interior and exterior trim parts, building profiles, exterior wall coatings, roofing materials, outdoor billboards and plastic-steel windows and doors. These products are exposed to the harsh natural climate for a long time, and the fading resistance is directly related to the service life and aesthetic value of the products.

Packaging and printing field: Involving the food packaging, pharmaceutical packaging, cosmetic packaging, the various commercial printed matters and labels. It is ensured that during the shelf display or transportation and storage, the packaging colours are stable, the brand marks are clear, and the information readability is not affected.

Cultural heritage and art protection field: Applied to the textile cultural relics, murals, painted works, archive papers and historical photos. Through the non-destructive or micro-destructive testing, the aging and fading state of the materials is evaluated, providing the data support for the relic restoration, preservation environment control and preventive protection.

Chemical raw material field: For the upstream chemical products such as the dyes, pigments, colour masterbatches, colourants and light stabilizers. The producers calibrate the product grades through the strict fading testing, and the downstream users select the appropriate raw materials accordingly to ensure the colour stability of the final products.

Transportation and safety marking field: Including the road marking paints, traffic sign reflective films, vehicle number plates and safety warning clothing. The colour fading of these products directly affects their visibility and warning effect, and is related to the public safety, so there are strict colour fastness to light requirements.

Testing Methods

Xenon arc lamp aging test method: A xenon arc lamp is used to simulate the full-spectrum sunlight, accelerating the material aging by controlling the light intensity, temperature, humidity and dark/spray cycles. This method is the internationally common core method of the light resistance testing, with the standards such as ISO 105-B02 (textiles), ISO 4892-2 (plastics) and ASTM G155.

Fluorescent UV lamp aging test method: The fluorescent UV lamps (such as the UVA-340 and UVB-313) are used to mainly simulate the UV band in the sunlight, accelerating the photo-aging process. This method is sensitive to the fading phenomenon caused by the UV light, with a relatively short test cycle, and the commonly used standards include ASTM G154 and ISO 4892-3.

Carbon arc lamp aging test method: A traditional accelerated aging method still used in some standards and industries, especially common in the Japanese JIS standard system. The spectral energy distribution of the carbon arc lamp is different from the sunlight, and needs to be selected and used according to the specific product standards.

Natural sunlight exposure method: The samples are placed in the actual outdoor environment (such as the exposure field), receiving the combined action of the real sunlight, rain and temperature. This method has the most true and reliable results, but takes a long time (several months to years), and is commonly used for verifying the correlation of the accelerated aging tests or carrying out the benchmark research. The standards such as the ISO 877 series.

Blue wool standard comparison method: Mainly applied to the colour fastness to light testing of the textile. The sample is simultaneously exposed with a series of blue wool standards of the known light fastness grades, and the light fastness grade of the sample is rated by comparing the fading degrees of the standards and the sample. The standards such as ISO 105-B01 and AATCC TM16.

Instrumental colour measurement method: A spectrophotometer or colorimeter is used to precisely measure the colour coordinates (such as the L*, a* and b* values) of the sample before and after the aging testing, calculating the colour difference ΔE. This method provides the objective and quantified data, avoiding the subjectivity of the visual rating, and is the basis for the result judgement of most modern fading tests.

Testing Standards

Domestic Standards:

1. GB/T 8427, Textiles — Tests for colour fastness — Colour fastness to artificial light: Xenon arc fading lamp test

2. GB/T 16422.2, Plastics — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps

3. GB/T 16422.3, Plastics — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps

International Standards:

1. ISO 105-B02, Textiles — Tests for colour fastness — Part B02: Colour fastness to artificial light: Xenon arc fading lamp test

2. ISO 4892-2, Plastics — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps

3. ISO 4892-3, Plastics — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps

4. ASTM G155, Standard practice for operating xenon arc lamp apparatus for exposure of materials

5. ASTM G154, Standard practice for operating fluorescent ultraviolet (UV) lamp apparatus for exposure of materials

6. ISO 877, Plastics — Methods of exposure to solar radiation

7. AATCC TM16, Colorfastness to light

Note: The applicable standard can be selected according to the product use and customer trade requirements; standards agreed in the contract take precedence over general standards.

Testing Instruments and Equipment

Xenon arc lamp aging test chamber: The core equipment, equipped with a filter system to simulate the solar spectra under the different environments (such as the sunlight and the sunlight filtered through the window glass). It has the precise light intensity control system, blackboard/black standard temperature control system, relative humidity control system and the programmable spray/condensation function, and can execute the complex test cycles.

Fluorescent UV aging test chamber: Multiple parallel arranged fluorescent UV lamp tubes are installed inside, providing the high-intensity UV radiation. The equipment has a relatively simple structure and low operating cost, and is widely used in the rapid screening and quality control of the UV-sensitive materials.

Natural climate aging test rack: A sample rack made of the materials with the excellent weatherability (such as the aluminium alloy) at a fixed angle (such as 45°) or an adjustable angle, placed in the outdoor exposure field. It is usually equipped with the sample clamping devices and the necessary environmental monitoring instruments (such as the pyranometers and temperature and humidity recorders).

Spectrophotometer: A precision optical instrument for the colour measurement. By measuring the reflectance or transmittance of the sample within the whole visible light wavelength range, the chromaticity values under the various colour spaces are calculated. It is the essential equipment for evaluating the fading degree and quantifying the colour difference, and needs to be regularly calibrated.

Standard light source colour matching cabinet: Provides the various standard light sources such as the D65, CWF, TL84 and UV, used for the visual colour comparison and rating under the controlled lighting conditions, especially the comparison rating of the blue wool standards. It ensures the consistency of the observation conditions and the reliability of the evaluation results.

Radiometer and calibration system: Used to measure and calibrate the irradiance of the light surface in the aging test chamber (usually expressed in W/m² at a specific wavelength or wavelength band), ensuring that the test conditions meet the standard requirements. The regular calibration is the key to ensuring the comparability of the test results between the different laboratories and equipment.