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Color fastness, how to improve Mar 27, 2018

Color fastness is a type of color fastness, also known as color fastness or color fastness to bleed, which refers to the migration of dye or residual floating color on the fabric, mainly reflecting the fabric after washing or being exposed to rain. The degree of contamination that causes dyes to elute at dyeing sites and shift to white or light-colored base fabrics comes from Japan. It is also called the "big pill method" in the Japanese test method.

Color weeping fastness has now become one of the common testing items for Japanese singles. Generally speaking, it is required to reach level 4 or above 4-5, which is mainly manifested in medium and dark colors. It is often associated with color fastness. Good color fastness and good weeping fastness will also be good.

The improved color fastness of cotton fabrics can be improved and strengthened from the following major aspects:

1.choose the right dye
Because the dyes are often accompanied by a small amount of incomplete dyes in the synthesis, the presence of these dyes will not only affect the color fastness but also affect the other color fastness. Therefore, the color fastness test should be done before use. At the same time, attention should be paid to the use of reactive dyes in which the water-soluble groups in the dye structure are not too high and the directness is intermediate.

2.Pay attention to the impact of water quality
The calcium and magnesium ions in the water will form insoluble matter with the dye and adsorb on the surface of the fiber, becoming floating color and hindering the diffusion and penetration of the dye, reducing the color fastness and even affecting the shade and vividness. Therefore, soft water or chelating dispersant must be added. Wait.

3.to strengthen the washing and soaping process
The residual alkali salts on the fibers, hydrolysis, and the floating color of the unbound dyes are the key factors affecting the fastness, and high-performance anti-soap soaping agents with excellent properties should be selected, and soaps should be soaped under neutral or weak acid as much as possible. Higher temperatures are used to wash off unbound dyestuffs inside the fabric, but it is also important to note that too high a temperature can cause breakage of bonded dyes, especially under alkaline conditions.

GESTER color fastness


4.using solid color processing
The use of excellent cations and reactive fixatives can block the water-soluble groups of the dyes, making the dyes insoluble in the lake and depositing in the fibers, reducing the water solubility of the dyes, while a small amount of hydrolyzed dyes can also participate in the fixation. Cross-linking further increases the binding force with the fiber, thereby effectively improving the wet processing of the dye, the fastness of the color cry, etc., and if necessary, individual deep color shades can also be subjected to a re-fixation process.


Of course, in addition to paying attention to the above points, whether the quality of the grey cloth itself and the pretreatment, bleaching and mixing, or even the dyeing process is reasonable will all affect the dye's ability to fully absorb, diffuse, and anchor, further standardize the operation and optimize the process to avoid staining. The formation of too much dye on the surface of the fiber and the phenomenon of dyeing back is to ensure that the color fastness of the reactive dyes is also the basis and guarantee for improving the color fastness.

 

GESTER color fastness tester:
  1. Electronic Crockmeter GT-D04
  2. Colour Fastness & Fabric Washing Fastness Tester GT-D07
  3. Crockmeter/ Rubbing Fastness Tester GT-D05

Electronic Crockmeter

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