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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard is redrafted and modified in relation to ISO 20433: 2012 Leather—Tests for colour fastness—Colour fastness to crocking.
The following technical changes have been made in this standard with respect to ISO 20433: 2012. so as to adapt to the actual situation in China:
——The second paragraph of "1 Scope" is deleted (see Clause 1 of ISO 20433: 2012)
——The adjustments of technical deviations are made for the normative references in this standard so as to adapt to the technical documents in China. The adjustments are mainly reflected in Clause 2 "Normative references" with the details as follows:
GB/T 251 identical to the international standard replaces ISO 105-A03 (see 4.3 hereof);
GB/T 33729 that is modified in relation to the international standard replaces ISO 105-F09 (see 4.2 hereof);
GB/T 39364 that is modified in relation to the international standard replaces ISO 2418 (see 5.1 hereof);
QB/T 2707 that is modified in relation to the international standard replaces ISO 2419 (see 5.3 hereof);
ISO 105-A01 and ISO 105-A04 are deleted (see Clause 2 of ISO 20433: 2012);
GB/T 6682 is added (see 4.4 hereof);
——The description of colour fastness testing in "3 Principles” is deleted (see Clause 3 of ISO 20433: 2012);
——The requirement that the rubbing finger is a cylinder is added in "4.1 Rubbing fastness test device" (see 4.1 hereof);
——"4.4 Spectrophotometer or colorimeter for assessing staining” is deleted (see 4.4 of ISO 20433: 2012);
——Requirements for test water are added (see 4.4 hereof);
——"4.5 Standard light source" is added (see 4.5 hereof);
——Requirements for sampling of non-standard positions are added (see 5.1 hereof);
——The sampling quantity is modified and the requirements for specific sampling direction are added (see 5.2 hereof);
——The direction requirement of fixing cotton rubbing cloth on the rubbing finger is added, and the description of moving distance and pressure (see 6.2 hereof; 6.2 of ISO 20433: 2012);
——The content of evaluating staining results by instrument method is deleted (see Clause 7 of ISO 20433: 2012);
——The requirement of illumination conditions when evaluating results is added (see Clause 7 hereof);
——"8 Precision” is changed to "8 Evaluation error", and "For the visual grey scale evaluations, an inter-person precision of ± 0.5 grey scale units is normal" is changed to "The difference between evaluation results among different evaluators shall not exceed half grade" (see Clause 8);
——The content of the test report is adjusted (see Clause 9).
For the convenience of application, the following editorial or structural modifications are made in this standard:
——The description of the influence of leather surface treatment or finishing on the test in "1 Scope" is adjusted to the note of "3 Principle";
——The note on the source of apparatus in "4.1 rubbing fastness test device" is deleted;
——The note on material source in "4.2 White cotton rubbing cloth" is deleted;
——"5 Test specimens" is subdivided into "5.1 Sampling", "5.2 Preparation of specimen" and "5.3 Conditioning of specimen";
——The subclause titles are added in "6 Procedure";
——Annex A (informative) “Apparatus and materials” is deleted;
——Note on result evaluation is added.
This standard was proposed by China National Light Industry Council.
This standard is under the jurisdiction of the National Technical Committee on Leather of Standardization Administration of China (SAC/TC 252).
Leather—Tests for colour fastness—
Colour fastness to crocking
1 Scope
This standard specifies a method for determining the color fastness to crocking of leather surface by reciprocating rubbing with a white cotton cloth.
This standard is applicable to the test of color fastness to crocking of various types of coloured leather surfaces.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 251 Textiles—Tests for colour fastness—Grey scale for assessing staining (GB/T 251-2008, ISO 105-A03, 1993, IDT)
GB/T 6682 Water for analytical laboratory use—Specification and test methods (GB/T 6682-2008, ISO 3696: 1987, MOD)
GB/T 33729 Textiles—Tests for colour fastness—Cotton rubbing cloth (GB/T 33729—2017, ISO 105-F09: 2009, MOD)
GB/T 39364 Leather—Chemical, physical, mechanical and fastness tests—Sampling location (QB/T 39364-2005, ISO 2418: 2017, MOD)
QB/T 2707 Leather—Physical and mechanical tests—Sample preparation and conditioning (QB/T 2707-2018, ISO 2419:2012, MOD)
3 Principle
Specimens of leather are rubbed with a dry or wet white cotton cloth attached to a cylindrical finger that is moved to and from under controlled conditions. Colour transferred to the white cotton cloth is assessed with the grey scale for staining.
Note: Since treatments of the leather as well as surface finishes can affect the degree of colour transfer, the test can be made before and/or after such treatments, which shall be indicated in the test report.
4 Apparatus and materials
4.1 Rubbing fastness test device, for determining the colour fastness to crocking. The device shall have a rubbing finger consisting of a cylinder of 16 mm ± 0.1 mm diameter which is driven to carry out a linear reciprocating motion along a 100 mm ± 5 mm track on the specimen, exerting a downward force of 9 ± 0.2 N.
4.2 White cotton rubbing cloth, complying with GB/T 33729. The cloth is cut into squares measuring approximately 50 mm×50 mm, for the rubbing finger in 4.1.
4.3 Grey scale for assessing staining, complying with GB/T 251.
4.4 Test water, Grade 3 according with GB/T 6682.
4.5 Standard light source, D65.
5 Sampling and preparation of specimens
5.1 Sampling
It shall be carried out according to GB/T 39364. Where sampling from standard positions (e.g. from finished products like shoes, garments, etc.) is impossible, sampling from any position within the available area is allowed and the specimens shall be representative and details about sampling shall be given in the test report.
5.2 Preparation of specimen
Four pairwise perpendicular specimens with dimensions not less than 140 mm×50 mm are cut out and used for dry rubbing and wet rubbing tests respectively.
5.3 Conditioning of specimen
Prior to testing, condition the specimens and rubbing cloth for at least 24 h in accordance with QB/T 2707.
6 Procedure
6.1 General
Fasten each specimen securely to the baseboard of the test device so that the surface to be tested is uppermost and the long direction of the specimen follows the track of the rubbing finger. Test the specimen by the procedures in 6.2 and 6.3.
Foreword i
1 Scope
2 Normative references
3 Principle
4 Apparatus and materials
5 Sampling and preparation of specimens
6 Procedure
7 Result evaluation
8 Evaluation error
9 Test report
