There are several things in textile testing that are related to color fastness testing. Many people may not know what color fastness means and why there is a need to test the color fastness. Please know that color fastness has a great influence on us. And there are many test items on color fastness. We will explain them one by one.
 
Color fastness is also called dye fastness. It refers to the resistance of the color of textiles to various effects during processing and use.
 
It refers to the degree of fading of dyed fabrics subjected to external factors (squeezing, rubbing, washing, rain, exposure, light, seawater immersion, saliva immersion, water stains, sweat stains, etc.) during use or processing.
 
It evaluates the fastness level based on the discoloration of the sample and the staining of the undyed lining fabric.

Textile color fastness test is a routine test item in the internal quality test of textiles. It is an important indicator of fabric assessment.
 
Why do we need to test color fastness?
 
Whether the color fastness is good or poor directly affects the beauty of wearing and the health and safety of the human body. During the wearing process, products with poor color fastness will cause the pigment on the fabric to fall off and fade when exposed to rain or sweat. And the particles of the dye and heavy metal ions may be absorbed by the human body through the skin and endanger the health of the human skin. On the other hand, it will also cause the staining of other clothing worn on the human body.
 
Types of color fastness test
 
The dye fastness of the fabric is related to the type of fiber, yarn structure, fabric structure,dyeing method, dye type and external force.

Color fastness tests generally include color fastness to soaping, color fastness to rubbing, color fastness to perspiration, color fastness to water, color fastness to light (sun), color fastness to sea water, color fastness to saliva, color fastness to chlorine water, color fastness to dry cleaning, color fastness to heat and pressure, etc. Sometimes there are some special requirements for color fastness according to different textiles or different environments.
 
Usually, when the color fastness test is carried out, it is the degree of discoloration of the dyed material and the degree of staining to the lining that matters. The color fastness is rated, except for the light fastness of eight, the rest are all five. The higher the grade, the better the color fastness.
 
The color fastness to soaping is to simulate the color change of textiles and the staining of other fabrics during the washing process of the washing liquid. The sample simulates washing by colliding with the container and stainless steel beads.
 
The color fastness to rubbing is the degree to which the color of the simulated colored textile is transferred to another fabric surface due to rubbing. It can be divided into dry rubbing and wet rubbing.
 
The color fastness to perspiration is the fastness of simulated textiles to artificial perspiration.
 
The color fastness to water is the degree to which the color of the simulated textile changes after being immersed in water.

The color fastness to light (sunlight) is the degree to which the simulated textiles discolors under the sunlight.

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