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GB/T 42950-2023 English PDF (GBT42950-2023)

GB/T 42950-2023 English PDF (GBT42950-2023)

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GB/T 42950-2023: Leather - Tests for colour fastness - Colour fastness to saliva

This document describes a test method for the colour fastness to saliva of leather. This document is applicable to the determination of colour fastness to saliva of various types of leather.
GB/T 42950-2023
GB
NATIONAL STANDARD OF THE
PEOPLE'S REPUBLIC OF CHINA
ICS 59.140.30
CCS Y 46
Leather - Tests for colour fastness - Colour fastness to saliva
(ISO 20701:2017, MOD)
ISSUED ON: AUGUST 6, 2023
IMPLEMENTED ON: MARCH 1, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 6
4 Principle... 6
5 Apparatus and materials ... 7
6 Reagents ... 7
7 Sampling and specimen preparation ... 8
8 Test steps ... 9
9 Result evaluation ... 9
10 Assessment error ... 9
11 Test report ... 9
Foreword
This document was drafted in accordance with the provisions of GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.
This document was modified in relation to ISO 20701:2017 Leather - Tests for colour fastness - Colour fastness to saliva.
Compared with ISO 20701:2017, this document has made the following structural adjustments:
-- The content "5.10 Spectrophotometer or colourimeter for assessing change in colour and staining" is deleted;
-- 6.3 corresponds to 6.3 and 6.4 in ISO 20701:2017;
-- "References" is deleted.
The technical differences between this document and ISO 20701:2017 and their reasons are as follows:
-- In the introduction to the chapter "Terms and definitions", EN 15987 (see Chapter 3) has been replaced with the normative reference QB/T 2262 to adapt to Chinese technical conditions and facilitate use;
-- The specific content about the ISO and IEC terminology online database in "Terms and definitions" (see Chapter 3 of ISO 20701:2017) is deleted, which has no practical significance for the use of Chinese standards; the understanding and use will not be affected after deletion;
-- The description of specific test conditions and colour fastness test in "Principle" (see Chapter 4 of ISO 20701:2017) is deleted, which does not conform to the writing habits and requirements of Chinese standards and duplicates the conditions in the test steps, and the understanding and use will not be affected after deletion;
-- The explanation of test methods in the chapter "Scope" is adjusted to the content of the chapter "Principle" and changed to a note (see Chapter 4; see Chapter 1 of ISO 20701:2017), which conforms to the writing habits of Chinese standards and is easy to understand;
-- Regarding the requirements for the grey scales for assessing staining, ISO 105- A03 (see 5.8) has been replaced by the normatively referenced GB/T 251 to adapt to Chinese technical conditions and facilitate use;
Leather - Tests for colour fastness - Colour fastness to saliva
1 Scope
This document describes a test method for the colour fastness to saliva of leather. This document is applicable to the determination of colour fastness to saliva of various types of leather.
2 Normative references
The following documents contain the provisions which, through normative reference in this document, constitute the essential provisions of this document. For the dated referenced documents, only the versions with the indicated dates are applicable to this document; for the undated referenced documents, only the latest versions (including all the amendments) are applicable to this document.
GB/T 250 Textiles - Tests for colour fastness - Grey scale for assessing change in colour (GB/T 250-2008, ISO 105-A02:1993, IDT)
GB/T 251 Textiles - Tests for colour fastness - Grey scale for assessing staining (GB/T 251-2008, ISO 105-A03:1993, IDT)
GB/T 6151 Textiles - Tests for colour fastness - General principles of testing (GB/T 6151-2016, ISO 105-A01:2010, MOD)
GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T 6682-2008, ISO 3696:1987, MOD)
GB/T 39364 Leather - Chemical, physical, mechanical and fastness tests - Sampling location (GB/T 39364-2020, ISO 2418:2017, MOD)
QB/T 2262 Terms of Lether Industry
3 Terms and definitions
The terms and definitions defined in QB/T 2262 apply to this document.
4 Principle
The filter paper soaked in artificial saliva is closely attached to the leather specimen to 8 Test steps
8.1 Cut the qualitative filter paper (5.1) into strips of approximately 80 mm??15 mm. 8.2 Soak a cut filter paper strip in artificial saliva (6.3) until it is completely moistened (it is advisable not to drip when the strip is taken out).
8.3 Place the soaked filter paper strip (8.2) on the test surface of the leather specimen, ensuring that the filter paper strip is tightly attached to the surface of the specimen. If the surface of the specimen is uneven, tape (5.2) or film (5.3) can be used to fix the filter paper strip on the leather specimen. The length of the tape shall cover the total length of the filter paper strip, and leave at least 10 mm of length beyond both ends of the filter paper strip to allow it to be fixed in a dry place on the specimen. NOTE: The test surface refers to the wearing surface of the leather, that is, the exposed and visible surface during use, which is usually the grain surface of the leather or may be the suede surface. 8.4 Put an appropriate amount of deionized water (6.1) at the bottom of the desiccator (5.4), and put it into the oven (5.5) to preheat to (37??2) ??C. Without taking out the desiccator (5.4), place the combined specimen (8.3) horizontally on the stand (above the water surface) of the desiccator (5.4) and keep it at the temperature of (37??2) ??C for (120??5) min.
8.5 Take out the combined specimen from the desiccator (5.4), separate the filter paper strip and the leather specimen, and hang them to dry at room temperature. 9 Result evaluation
After the filter paper strip and specimen dry, use the grey scale for assessing staining (5.8) and the grey scale for assessing change in colour (5.9) to assess the staining grade of the filter paper strip and the grade of change in colour of the leather specimen under the D65 light source specified in GB/T 6151.
10 Assessment error
The difference in evaluation results between different testers shall not exceed half a level.
11 Test report
The test report shall contain the following content:

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