Insufficient dye fastness is a fatal flaw for cotton, polyester and other fabrics. Different dye fastness requirements, It will cause a big cost difference, so many fabric manufacturers often require dyeing factories to use lower-cost domestic dyes when dyeing to reduce dyeing costs. This often brings about a series of problems in dyeing fastness.
General concept of color fastness
Dye fastness is the quality requirement for dyed and printed fabrics. Because dyed fabrics will be discolored or discolored due to light, sweat, friction, washing, ironing and other reasons during wearing and storage, This affects the appearance of the fabric or garment and changes the dyeing state. The nature or degree of dyeing can be expressed by dyeing fastness. The dyeing fastness of fabric is related to yarn structure, fabric structure, printing and dyeing method, dye type and external force. It can be divided into sun fastness, washing or soaping fastness. Fastness to rubbing, perspiration fastness, ironing fastness and sublimation fastness, etc.
1. Sunlight fastness
Sunlight fastness refers to the degree of discoloration of colored fabrics by sunlight. The test method can be either sunlight exposure or insolation machine exposure. The fading degree of the sample after exposure is compared with the standard color sample, and it is divided into 8 levels, with 8 being good and 1 being poor. Fabrics with poor sun fastness should not be exposed to the sun for a long time and should be placed in a ventilated place to dry in the shade.
2. Washing fastness
Washing or soaping fastness refers to the degree of color change of dyed fabrics after being washed with detergent. The gray graded sample card is usually used as the evaluation standard, that is, based on the color difference between the original sample and the sample after fading. Washing The fastness is divided into 5 levels, with level 5 being good and level 1 being poor. Fabrics with poor washing fastness should be dry cleaned. If wet cleaning is required, extra attention should be paid to the washing conditions, such as the washing temperature should not be too high and the washing time should not be too long.
3. Rubbing fastness
Rubbing fastness refers to the degree of color fading of dyed fabrics after rubbing, which can be divided into dry rubbing and wet rubbing. Rubbing fastness is measured by white cloth staining As an evaluation principle, the degree is divided into 5 levels (1~5). The larger the value, the better the rubbing fastness. The service life of fabrics with poor rubbing fastness is limited.
4. Perspiration fastness
Perspiration fastness refers to the degree of color fading of dyed fabrics after being immersed in sweat. Since the composition of artificially prepared sweat is different, perspiration fastness is generally measured in addition to separate measurements. Combined with other color fastnesses to evaluate. Perspiration fastness is divided into levels from 1 to 5, the larger the value, the better.
5. Ironing fastness
Ironing fastness refers to the degree of discoloration or fading of dyed fabrics when ironed. This degree of discoloration and fading is evaluated based on the staining of other fabrics by the iron at the same time. Ironing fastness is divided into Level 1~5, level 5 is good, level 1 is poor. When testing the ironing fastness of different fabrics, the test iron temperature should be selected.
6. Sublimation fastness
Sublimation fastness refers to the degree of sublimation phenomenon that occurs in dyed fabrics during storage. Sublimation fastness is used The gray grading sample card evaluates the degree of discoloration, fading and staining of white cloth after dry heat pressing. It is divided into 5 levels, 1 is poor and 5 is good.
The dye fastness of normal fabrics generally requires level 3~4 to meet the needs of wearing.
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