Abstract: This paper compares and analyzes the test standards of color fastness to washing GB / t3921-2008 and GB / t12490-2007, points out that different types of linings will affect the test results, puts forward the problems that should be paid attention to in the test process, and introduces the test methods and the selection skills of linings when testing the color fastness to washing of various textiles.

Color fastness to washing refers to the ability of textile color to withstand all kinds of washing. It is an important index to measure the use value of textiles. This paper mainly analyzes the similarities and differences between the color fastness test standard GB / t3921-2008 (color fastness to soaping of Textiles) and GB / t12490-2007 {color fastness test of textiles (color fastness to domestic and commercial washing), as well as the selection technology of relevant textile color fastness test technology.

1 Comparison of standards

1.1 test standard for color fastness to washing

At present, the new standard GB / t3921-2008 (color fastness to soaping of Textiles) for the color fastness to washing of textiles in China is an improvement on GB / t3921 The revision of 1-5-1997 standard will be officially implemented on December 1, 2008. The new standard integrates the five parts of the old standard, and modifies and adjusts the lining selection, combined sample cleaning and rating methods. The modification of this standard adopts the international standard iso105-cio: 2006 (textile color fastness test CIO part: color fastness to soaping or washing with soap and soda). This is a small and rapid test method for predicting the color fastness of textiles to washing in the laboratory. There are five washing methods from mild to severe, and the test temperature is 40 ~ 95.

1.1.1 principle

Sew the textile sample with one or two specified lining fabrics, put it into the soap solution or the mixture of soap and anhydrous sodium carbonate, mechanically stir it at the specified time and temperature, then rinse and dry it, and evaluate the discoloration of the sample and the staining of the lining fabric with gray sample card or instrument.

1.1.2 lining selection

The lining fabric used to test the color fastness to washing can be single fiber lining or multi fiber lining. The single fiber lining fabric shall comply with gb7565-1987 (textile color fastness test, specification for cotton and viscose fiber standard lining fabric), GB / t7568 1-2002 Textiles - Tests for colour fastness - Specifications for wool standard lining fabrics), GB / t7568.4-6-2002 Textiles - Tests for colour fastness - Specifications for polyester, polyacrylonitrile, silk and other standard lining fabrics, gb11403-1989 (tests for colour fastness of Textiles - Specifications for polyamide standard lining fabrics), GB / t13765-2002 (flax and ramie standard lining fabrics) and is0105-vo7-2oo1 (Specification for recycled acetate lining fabric) and other standard requirements; Multi fiber lining shall meet the requirements of gb11404-1989 (textile color fastness test, specification of multi fiber standard lining fabric).

The first single fiber lining of blended fabric selects the main fiber in the fabric composition; The second lining is the secondary fiber in the fabric composition. Taking polyester / cotton / nitrile (50 / 40 / 10) blended fabric as an example, the first lining for washing color fastness is polyester and the second lining is cotton]. The first single fiber lining of pure textile fabric is selected from similar fibers, and the second lining is selected according to table 1.

Multi fiber lining is composed of a variety of fibers. Because its structure, yarn and density are different from that of single fiber lining, the staining effect is also different. The commonly used SDC multi fiber adjacent cloth DW is taken as an example and tested according to GB / t3921a (1). The comparison results are shown in Table 2.

According to table 2, after the same fabric is washed under the same conditions, there is a certain difference in the staining of the corresponding lining between single fiber lining and multi fiber lining. In Table 2, there is a half grade difference between the inspection results of wool staining of pure cotton fabric, polyester staining and cloth staining of polyester / cotton fabric, and nylon and cotton staining of cotton / brocade fabric.

1.2 test standard for color fastness to domestic and commercial washing

GB / t12490-2007 (color fastness test for textiles - color fastness to domestic and commercial washing) is a revision of GB / t12490-1990 and was officially implemented on July 1, 2008. The standard adopts iso105-c06:1994 (textile color fastness test part C06: color fastness to domestic and industrial washing) standard, and modifies the pasting, control of relevant parameters of test solution, drying method and so on. The method is suitable for determining the color resistance of textiles to general domestic or commercial washing. The equipment requirements, operation process and lining selection are the same as those in GB / t3921-2008. The standard detergent required does not contain fluorescent brightener. Aatccob detergent or ECE detergent can be selected, which is different from GB / t3921-2008.

There are L6 kinds of washing conditions for this method (see Table 2 of the standard), among which the methods often cited in China's product standards are a1s and b2s in the test number. These two test conditions are applicable to the hand washing and machine washing color fastness test of textiles respectively. For example, a1s test condition is cited in the washing color fastness test of careful hand washing wool needle knitwear, low wool content and wool like knitwear, as well as decorative fabrics; B2s test conditions are cited in the washing color fastness test of machine washable wool knitwear.

1.3 comparison of color fastness standards to washing

Although GB / t3921-2008 and GB / t12490h2007 are related to the test methods of color fastness to washing, there are still differences between them.

1.3.1 scope of application, detergents and rating tools (Table 3)

1.3.3 lining and test methods

With different linings, the test results will be different. Take two pieces of fabrics with different compositions and colors, select multi fiber and single fiber lining respectively, and use five washing color fastness methods in the two standards to wash wool knitwear, low wool blended and wool like knitwear respectively, as well as the comparison of loading test. The results are shown in Table 5.

It can be seen from table 5 that the same washing method is adopted for the same fabric, but the test results (color fastness) are different when different kinds of linings are selected. The same lining is selected for a fabric. Due to different washing methods, the test results are also greatly different. With the increase of washing temperature, the color fastness level is getting lower and lower, but the color change result of the sample is not obvious.

Therefore, before determining the color fastness to washing, it is necessary to clarify the washing method and the type of lining, otherwise the test results are not comparable. In China's national and industrial standards, the staining of color fastness to washing is mainly to assess the staining of main and secondary components in fabrics; In export trade, buyers often use nylon or silk lining that is easy to stain to assess the washing and staining effect of fabrics. Therefore, the judgment conclusions of the same product are often quite different.

2 selection skills of detection technology for color fastness to washing

According to China's product standards and actual use, the washing color fastness test of fabrics, clothing (decoration) and home textile products can generally be selected according to the following methods:

2.1 fabrics

To test the color fastness to washing of fabrics, generally, the washing method should be selected according to its purpose. If the purpose is unknown, select according to the following methods:

① For silk, viscose, wool and nylon fabrics, refer to GB / t392l-2008a (1), and the test temperature is (40 ± 2) ℃.

② For cotton, hemp, polyester and acrylic fabrics, refer to GB / t3921-2008c (3), and the test temperature is (60 ± 2) ℃.

③ New fibers, such as lyocel fiber, modal fiber, milk protein fiber and soybean protein fiber, shall be determined according to the fiber properties and dyeing process. Generally, GB / t3921-2008a (1) standard is selected, and the test temperature is (40 ± 2) ℃.

2.2 clothing (decoration)

(1) Knitted clothing, knitted casual clothing, body underwear, thermal underwear, knitted skirt cover, infant knitted clothing, socks, bra and other products refer to GB / t3921-2008a (1), and the temperature is (40 ± 2) ℃. However, in cotton knitted products, cotton knitted underwear, T-shirts (except nylon), knitted sportswear and linen knitwear shall refer to GB / t3921-2008c (3), and the test temperature shall be (60 ± 2) ℃.

(2) According to the washing requirements of wool knitwear, the a1s or b2s method in GB / t12490-2007 is selected. The a1s procedure is selected for hand washing and the b2s procedure is selected for machine washing; A1s test conditions in GB / t12490-2007 shall be selected for low wool and imitation wool knitwear and cashmere sweater.

(3) Woven clothing, denim clothing, single clip clothing, skirt cover, infant clothing and jacket, the method of GB / t3921-2008c (3) is selected, and the test temperature is (60 ± 2) ℃; However, single clip clothing, skirt covers, infant clothing and jackets (including jackets made of nylon fabric) composed of silk, viscose, hemp and their blends shall use the method of GB / t3921-2008a (1), and the test temperature shall be (40 ± 2) ℃. Selection of raincoat and silk clothing GB / t3921-2008a (1).

2.3 home textiles

(1) Towels and bedding shall be tested for color fastness to washing according to GB / t3921-2008c (3) and the test temperature shall be (60 ± 2) ℃.

(2) The test method for color fastness to washing of decorative fabrics shall be carried out according to a1s conditions in GB / t12490-2007. If the instructions of the product are gentle washing or hand washing, steel balls shall not be used in the test.

proposal

(1) To test the color fastness of textiles to washing, the washing method and lining should be selected according to the needs of standards and trade. Single fiber lining can be selected for domestic trade, and multi fiber lining is commonly used for foreign trade.

(2) The test sampling shall be representative, especially for printing products, ensure that each color is taken, and pay attention to the correspondence of pattern color during rating.

(3) The combined sample is stitched on one short side. When the sample is yarn or loose fiber, the sample is half of the total mass of the lining fabric and stitched along the four sides.

(4) The test solution shall be preheated to the test temperature first, otherwise the test results will be affected.

(5) When rating, the eyes shall be perpendicular to the sample, and the light source shall be 45 ° to the sample., Keep the distance at 30 ~ 40cm; For glossy samples, the light source is vertical and the eye is 45 ° to the sample.

4 Conclusion

Due to the differences in test standards and methods, the test results of textile color fastness to washing are different. The assessment indicators of color fastness to washing of different products are different. Even for the same fabric, due to the different final products, different product standards should be implemented, and the final judgment results are also different. Therefore, China's textile and garment enterprises must understand the differences in detection methods of different color fastness standards, and fully understand the standard requirements of different products and the buyer's requirements, so as to control the quality, reduce risks and do a good job in textile trade.