Color fastness
According to statistics, fastness is one of the most frequently asked questions in all dyeing questions.
Dyeing fastness requires high quality of dyed and printed fabrics. The nature or degree of dyeing state variation can be expressed by dyeing fastness. It is related to yarn structure, fabric structure, dyeing and printing methods, dye types and external forces. Different dyeing fastness requirements will lead to great cost and quality differences. Uploading...
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Six Main Textile Fastness
The dyeing fastness of normal fabrics is generally required to be between 3 and 4 grades in order to meet the wearing requirements. The following contents summarize the six main textile fastnesses in dyeing and finishing:
One
Fastness to sunlight
Solar fastness refers to the degree of discoloration of colored fabrics by sunlight. The test method can be either sunshine or sunlight machine. The fading degree of the sample after sunshine is compared with the standard color sample, which can be divided into 8 grades, 8 grades are the best and 1 grades are the worst. Fabrics with poor fastness to sunlight should not be exposed to sunlight for a long time, and should be put in a ventilated place to dry in the shade.
Two
Rubbing fastness
Friction fastness refers to the degree of discoloration of dyed fabrics after friction, which can be divided into dry friction and wet friction. The rubbing fastness is evaluated by the staining degree of white cloth, which is divided into five grades (1-5). The larger the value, the better the rubbing fastness. The service life of fabrics with poor rubbing fastness is limited.
Three
Washing fastness
Washing or soaping fastness refers to the degree of color change of dyed fabrics after washing with detergent. Generally, the grey grading sample card is used as the evaluation standard, that is, the color difference between the original sample and the faded sample is used to judge. The washing fastness is divided into five grades, the best is grade 5 and the worst is grade 1. Fabrics with poor washing fastness should be dry cleaned. If wet washing is carried out, more attention should be paid to washing conditions, such as washing temperature should not be too high and time should not be too long.
Four
Ironing fastness
Ironing fastness refers to the degree of discoloration or fading of dyed fabrics during ironing. The degree of discoloration and fading is determined by the staining of the irons on other fabrics at the same time. The ironing fastness is classified into grade 1 to 5, grade 5 is the best and grade 1 is the worst. When testing the ironing fastness of different fabrics, the ironing temperature should be chosen well.
Five
Sweat fastness
Sweat fastness refers to the degree of fading of dyed fabrics after soaking in sweat. Sweat fastness is generally assessed in combination with other colour fastnesses, in addition to being determined separately, due to the different components of sweat manually prepared. Sweat stain fastness is classified into 1 ~ 5 grades, the larger the value, the better.
Six
Sublimation fastness
Sublimation fastness refers to the degree of sublimation of dyed fabrics during storage. The sublimation fastness was assessed by grey grading sample card. The degree of discoloration, fading and staining of white cloth after dry hot pressing was divided into five grades, the first grade was the worst and the fifth grade was the best.
How to control various fastness
After textile dyeing, the ability of the fabric to retain its original color can be expressed by testing various dyeing fastnesses. Commonly used indicators of dyeing fastness include washing fastness, rubbing fastness, sunshine fastness, sublimation fastness and so on.
The better washing fastness, rubbing fastness, sunshine fastness and sublimation fastness of fabrics, the better dyeing fastness of textiles.
The main factors affecting the above fastness include two aspects:
The first is the properties of dyes.
The second is the formulation of dyeing and finishing processes.
Selective dyes with good dyeing properties are the basis for improving the fastness of dyeing. The key to ensure the fastness of dyeing is to formulate reasonable dyeing and finishing processes. They complement each other and can not be neglected.
Washing fastness
The washing fastness of fabrics includes fading fastness and staining fastness. Generally, the worse the fading fastness of textiles is, the worse the staining fastness is.
When testing the staining fastness of a textile, the staining fastness of the fibers can be determined by examining the staining condition of the fibers to the six commonly used textile fibers (these six commonly used textile fibers usually include polyester, nylon, cotton, acetate, wool or silk, acrylic). The test of staining fastness of six kinds of fibers is usually carried out by qualified independent professional inspection companies, which is relatively objective and impartial.
For cellulose fiber products, the washing fastness of reactive dyes is better than that of direct dyes. The dyeing process of insoluble azo dyes, vat dyes and sulfur dyes is more complex than that of reactive dyes and direct dyes, so the washing fastness of the latter three dyes is better.
Therefore, in order to improve the washing fastness of cellulose fibre products, we should not only choose the right dyes, but also choose the right dyeing process. Proper strengthening of washing, fixing and soaping can obviously improve the washing fastness.
As far as the deep color of polyester fibers is concerned, the washing fastness after dyeing can meet the customer's requirements as long as the fabric is cleaned by reduction. However, most of the polyester fabrics are softened by dipping and rolling cationic organosilicon softeners to improve the handle of the fabrics. At the same time, anionic dispersants in disperse dyes may diffuse to the surface of the fabrics due to the thermal migration of dyes during high temperature setting, so the washing fastness of the deep-colored polyester fabrics after setting may not be qualified. This requires that not only the sublimation fastness of disperse dyes, but also the thermal migration of disperse dyes should be considered when selecting disperse dyes.
There are many ways to test the washing fastness of textiles. If we test the washing fastness of textiles according to different testing standards, we will draw a conclusion that it is not J Division. If the specific test criteria can be put forward when the customers put forward the specific washing fastness index, it will be beneficial to both sides.
