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What is lightfastness and why is it important?

Author:QINSUN Released in:2023-06 Click:125


1 What is lightfastness2 Why is lightfastness important3 How can you increase lightfastness3.1 Choose the right dye Process3.2 Appropriate fixative and plasticizer3.3 Choice of dye or color4 Lightfastness Tester4.1 Water-cooled Lightweather Fastness Test FY36004.2 Air-cooled Xenon Arc Tester YG611M4.3 DW601 Mercury-Tungsten Lightfastness Tester

What Lightfastness means the ability of a Fleck\'s ability to retain its original color when exposed to sunlight. Due to the wave-particle two-phase nature of sunlight, sunlight transmits energy in the form of photons, which has a strong impact on the molecular structure of dyes. According to the general regulations, the determination of sunlight is based on light fastness as a standard. In the laboratory, eFor simple control, artificial light sources are usually used and corrected if necessary.

The most common artThe official light source is xenon or carbon arc lamps. Under the light irradiation, the dye absorbs light energy, its energy level increases, its molecules are in an active state, and the hair dye system of the dye molecules changes or is destroyed. This will result in discoloration or fading of the dye. Sun fading is a complicated photochemical process. It is related to the structure of the dye, the dye concentration, the type of fiber and the external conditions.

Why is lightfastness important?

The light Fastness of fabrics is an important index for fabric testing. In general, the lightfastness test is used to simulate the use or cleaning of textiles in everyday life to determine their level of lightfastness.

The problem of lightfastness scheiNot to be small, but actually has a large impact on consumer health. It is directly related to the health and safety of the human body. If products with poor lightfastness are worn, the dye on the fabric will fall off and fade when encountering rain and sweat.

Dye molecules and heavy metal ions can be absorbed by the skin and cause harm to the health of the human body. On the other hand, they can contaminate other garments worn on the body or washed. At the same time, proof of lightfastness is very important.

Lightfastness is very important for textiles, so we strictly follow the requirements in the actual production process to ensure the quality of the products.

How can you increase lightfastness?Select the appropriate drying method

The sunfastness of dyed fabrics depends on the depth of dyeing. The bigger the Fdepth of dye, the larger the particles collected by the dye on the fabric, the lower the proportion of dye exposed to air per unit weight and the higher the sunfastness. In the case of light-colored fabrics, the proportion of dye on the fiber is all the lower, and the sunfastness tends to decrease accordingly. The factory declares the degree of sunfastness that can not meet the requirements is generally medium and light color. For some light brown fabrics, after the sun fastness test, the red light was almost completely lost, the color change is obvious.

Whether the dyeing process is chosen correctly, whether the washing and washing with soap after that If the dyeing is thorough, has an effect This depends on the amount of non-fixed dyes and hydrolysed dyes d in the fabric.

Suitable fixative and fabric softener

The use of fixative improves the rubbing fastness of reactive dyesfabrics, the wash fastness and the color fastness significantly. In general, the washfastness of fabrics that have been treated with cationic low molecular weight agents or polyamine color fixes is grade 4 to 5, but the sunfastness of fabrics that have been fixed with these types of color fixes has decreased. When cotton fabrics are softened with cationic fabric softener, the sunfastness of reactive dyes decreases, mainly because Note that after exposure to the sun, the fabric softener turns yellow, so the color of the fabric also changes.

Choice of color or colour

Selection by color depth

The color fastness of reactive dyes on cellulose fibers is directly proportional to the depth of the dyed color. That is, the darker the color, the better the color fastness to light. Therefore, when dyeing light varieties, the dye should be chosen with high light fastness. In addition, demMany finishing agents such as softeners and anti-wrinkle finishing agents are added to the fabric, which also reduce the lightfastness of the product. Dyes should be selected that are not sensitive to these finishing agents.

Dyes with good lightfastness and compatibility should be selected

Different dyes have different fading characteristics and even different photofading mechanisms. Sometimes the presence of one dye causes sensitization to fade another. When color matching, we should choose dYes, that does not sensitize each other and can even improve light stability. This is an important way to achieve high color fastness to light by properly controlling the drying process, fully bonding the dyes to the fibers and preventing dyes that are hydrolyzed and not fixede Dyes remain on the fibers.

Light fastness testerWater-cooled light weather fastness FY3600

Water-cooled light weather fastness


Water gauge for chilled weather conditions. To determine the color fastness and aging to sunlight, weather resistance and composite color fastness to sunlight and perspiration of colored textiles, leather, imitation leather, plastic, etc. by adjusting various parameters of irradiance, temperature, humidity and spray to simulate natural laboratory conditions . You can control real-time irradiance, irradiance, temperature and LuCheck and compensate humidity automatically.


Preset various specifications or customized programs meet various standards including AATCC, ISO, BS, JIS, etc.;

Touch screen and integrated PLC show the graph of the running test in real time. You can preset irradiance, temperature and humidity and draw their dynamic curves. The water-cooled 4500W xenon arc lamp system accurately simulates the sunlight spectrum. The system automatically compensates the irradiance and controls the irradiance, temperature and humidity in time via a closed circuit. Irradiation control, light irradiation sensor monitoring, digital adjustment, automatic compensation system, stepless irradiation control. Accurate chamber temperature control, irradiation temperature and heating increase the temperature, air conditioning and cooling system. YG611M air-cooledlter Xenon Arc Tester


The YG611M Air-Cooled Xenon Arc Tester is used to determine the color fastness and aging to sunlight, the weather resistance and the composite color fastness to sunlight and perspiration of colored textiles, leather, plastics, etc . etc. by setting various parameters for irradiance, temperature, humidity and spray to simulate natural laboratory conditions. You can control irradiance in real time, check and compensate irradiance, temperature and humidity automatically.


Weather Gauge

10.4-inch color touchscreen display, Windows operating system, concise user interface, few setting operations and simple operation; Real-time GraphicsGraphic display allows the operator to easily access the testing process. Independent control of each sample to be tested, the test time of the samples is controlled separately. Set the time for each sample. When the set time has elapsed, the appropriate sample can be taken Run and continue testing the remaining samples. Automatic reminder when testing of each sample is finished. DW601 Mercury-Tungsten Lightfastness Tester

Application: The DW601 Mercury-Tungsten Lightfastness Tester is used to determine the lightfastness of textiles exposed to a mercury lamp.

Function :

Imported mercury lamp with original packaging, 500w high power long life lampr;

Mercury arc lamp tester