Dyeing fastness refers to the ability of dye or pigment to keep its original color under the influence of various external factors during the use of dyed products or in the process of dyeing. It is also the quality requirement of dyeing and printing fabrics. Ken color or discoloration will occur to dyed fabrics during wearing and keeping due to light, sweat, friction, washing, ironing and other reasons, which will affect the aesthetic appearance of fabrics or clothing. The nature or degree of variation in dyeing status can be indicated by color fastness. The dyeing fastness of fabric is related to fiber type, yarn structure, fabric structure, printing and dyeing method, dye type and external force. It can be divided into insolation fastness, water or soap wash fastness, friction fastness, perspiration sores fastness, ironing fastness and sublimation fastness.

1, sun fastness

Sunfastness is the degree to which colored fabrics change color when exposed to sunlight. The test method can be used either by sun exposure or by sun exposure machine. The fading degree of the sample after sun exposure is compared with the standard color sample. The grading standard has two kinds of wool blue standard and gray card. The US standard is divided into five levels, with five being the best and one the worst. The fabric with poor insolation fastness must not be insolated for a long time below sunshine, it is appropriate to dry in ventilated place. The general use of xenon lamp irradiation 24 hours test.

2, washing fastness

Washing or soap-washing fastness refers to the degree of color change of dyed fabric after washing with detergent. Gray grading sample card is usually used as the assessment standard, which depends on the color difference of the original sample and the sample after fading. There are five grades of washing fastness, with 5 being the best and 1 the worst. Fabrics with poor washing fastness should be dry cleaned. If wet washed, double attention should be paid to washing conditions, such as washing temperature should not be too high or time should not be too long. Washing fastness is divided into two indexes, the original change and white cloth staining, white cloth staining is divided into cotton, nylon, polyester, wool, acrylic, acetate six kinds of fiber. The test temperature is 40/50/60/95 degrees, general silk and wool use 40 degrees standard, cellulose fiber use 60 degrees.

3，Friction fastness

Friction fastness refers to the color loss of dyed fabric after friction, which can be divided into dry friction and wet friction. The friction fastness is evaluated by the color staining degree of the white cloth, which is divided into 5 grades (1-5). The greater the value, the better the friction fastness.

4，The fastness to perspiration

Perspiration fastness refers to the degree of discoloration of dyed fabric soaked in sweat. Perspiration fastness because of the artificial preparation of sweat components are not the same, so generally in addition to separate determination, but also with other color fastness combined with assessment. Perspiration fastness is graded from 1 to 5, with the higher the better. In European standard and national standard, sweat fastness is divided into acid sweat fastness and alkali sweat fastness.

5，Ironing fastness

Ironing fastness refers to the degree of discoloration or discoloration of a dyed fabric during ironing. The degree of discoloration and discoloration is assessed by the simultaneous staining of other fabrics with the iron. Ironing fastness is rated from 1 to 5, with 5 being the best and 1 the worst. When testing the ironing fastness of different fabrics, the ironing temperature should be selected.

6, sublimation fastness

Sublimation fastness refers to the degree to which sublimation occurs during storage of dyed fabrics. Sublimation fastness The color change, fading and staining degree of white cloth after dry pressing were evaluated by grey grading sample card, which were divided into 5 grades, with 1 being the worst and 5 being the best. This test is generally used for dyeing polyester fabrics with disperse dyes.

7, chlorine immersion fastness

Chlorine immersion fastness is generally aimed at some swimsuits, because the sea water contains chlorine, easy to make the fabric fade. Now the city tap water also contains effective chlorine, some hospital, hotel supplies need to be disinfected with chlorine-containing detergents, so the chlorine-resistant bleaching fastness put forward higher and higher requirements.

8，Light fastness to sweat

Some fabrics have been tested to have good perspiration fastness and sun fastness, but in the actual use process, especially in summer, perspiration immersion and sun fastness are very easy to fade, which puts forward a new requirement, and at the same time, a new standard has been created.

9, fastness to peroxide

Most of the present washing powders are added with peroxides such as peracetic acid and some activators, which cause the textiles to be oxidized in the washing process and fade. So the textile color fastness to have a certain tolerance to peroxide.

Normal fabric dyeing fastness, generally required to reach 3~4 grade to meet the needs of wearing.

Other fastness include weather fastness, SOB fastness, saliva fastness, blister fastness, dry cleaning fastness, etc. These fastness put forward higher and higher requirements for textile printing and dyeing processing.