GB/T 3921-2008Textiles - Tests for Colour Fastness - Colour Fastness to Washing with Soap or Soap and Soda (English PDF)

1 Scope

This Standard specifies methods for determining the colour fastness to washing of all kinds of textiles that are commonly used in households, It includes 5 type of tests on different washing procedures from mild to severe procedure.

This Standard is only used to determine the effect of washing on the colour fastness of the textile. It is not intended to reflect the result of the comprehensive laundering procedure.

2 Normative References

The following normative documents contain provision which, through reference in this text, constitute the provisions of this Standard. For dated reference, subsequent amendments (excluding amending error in the text) or revisions of these publications do not apply. However, all parties who enter into an agreement according to this Standard are encouraged to study whether the latest edition of the normative document is applicable. For undated references, the latest edition of the normative document referred to applies.

GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods (GB/T 6682-1992, ISO 3696: 1987, NEQ) GB/T 7568.4 Textiles - Tests for Colour Fastness - Specification for Polyester GB/T 13765 Textiles - Tests for Colour Fastness - Specification for Standard Adjacent Fabric of Linen and Ramie ISO 105-F07 Textiles - Tests for colour Fastness - Part F07: Specification for Secondary Acetate Adjacent Fabric

3 Principle

A specimen of the textile in contact with one or two specified adjacent fabrics is mechanically stirred under specified conditions of time and temperature in a soap, or soap and soda ash solution, then rinsed and dried. The change in colour of the specimen and the staining of the adjacent fabric, or fabrics, are assessed with reference to the original fabric, either with the grey scales or instruments.

4 Apparatus

assembly is rotated at a frequency of (40±2) r/min. The temperature of the water bath is thermostatically controlled to maintain the test solution within ± 2°C of the prescribed temperature.

Other mechanical devices may be used for this test, provided that the results are identical with those obtained by the apparatus described in 4.1. Be aware of possible contamination (see the note in 7.2).

5 Reagents and Materials

The soap shall be free from fluorescent brightening agents.

6 Test Specimen

6.1 If the textile to be tested is fabric, the composite-specimen shall be prepared according to one of the following methods:

adjacent fabric next to the face side of the specimen.

6.2 Yarn may be knitted into fabric and tested in this form. When yarns or loose fibres are to be tested, take the yarn or loose fibres of which the mass is approximately equal to one-half of the combined mass of the adjacent fabrics. Prepare the composite-specimen according to one of the following methods:

a) Place it between a 100mm×40mm piece of the multifibre fabric and a piece of the non-dyeable fabric (5.6). Sew them along all four sides (see GB/T 6151).

b) Place it between 2 single-fibre adjacent fabrics with specification of (40 ± 2) mm × (100 ± 2) mm. Sew along all four sides.

6.3 Determine the mass, in grams, of the composite-specimen by using the balance (4.2) to aid the accurate bath ratio volumes.

7 Operation Procedures

7.1 Prepare the soap solution (5.3) according to the test used. Place the composite-specimen in the container together with the specified number of steel balls (4.4). Add the necessary amount of soap solution that has preheated to ±2°C of the test temperature, according to Table 2. Bath ratio is 50:1. Close the container. Immediately operate the machine at the temperature and for the time specified in Table 2. And start the timing. Care should be taken to differentiate clearly between containers used for testing with and without fluorescent brightening agents. Note: Containers (4.1) could be contaminated by the fluorescent brightening agents present in other test detergents and in commercial detergents. This could affect the colour fastness ratings of test specimens if such contaminated containers were subsequently used for tests using a detergent without fluorescent brighteners. them twice in Grade 3 water (5.4) respectively. Then rinse them clean in running water. 7.4 For all methods, extract the excess water from the composite-specimen by squeezing the test specimen by hand. Open out the composite-specimen by cutting the stitching except on one of the shorter sides if necessary. 7.5 Dry the specimen by pressing it flat between two filter papers to remove excess water. Then dry by hanging it in air at a temperature not exceeding 60 °C; the specimen and adjacent fabric are contacted only at the line of stitching. 7. […]

8 Test Report

Test report shall include the following information:

b) All details of test specimen;

e) If single-fibre adjacent fabrics were used, the numerical rating for staining of each kind of adjacent fabric used;

f) If a multifibre adjacent fabric was used, the staining of each type of fibre in the multifibre adjacent fabric, and the type of multifibre adjacent fabric used;

g) Any deviation details of this Standard and abnormal phenomena in tests.