GB/T 39366-2020 English PDF (GBT39366-2020)

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GB/T 39366-2020: Leather - Tests for colour fastness - Colour fastness to crocking
GB/T 39366-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Leather - Tests for colour fastness - Colour fastness
to crocking
(ISO 20433:2012, MOD)
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: JUNE 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 6 
2 Normative references ... 6 
3 Principle ... 6 
4 Instruments and materials ... 7 
5 Sampling and sample preparation ... 7 
6 Test procedure ... 7 
7 Result assessment ... 8 
8 Assessment error ... 8 
9 Test report ... 9 
Foreword
This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard uses the redrafting method to modify and adopt ISO 20433:2012,
“Leather - Tests for colour fastness - Colour fastness to crocking”.
Compared with ISO 20433:2012, this Standard makes the following technical
modifications to adapt to the actual situation of China:
-- Delete the second paragraph in "1 Scope" (see Chapter 1 of ISO
20433:2012);
-- With regard to the normative references, this Standard makes technical
adjustments to adapt to the technical conditions of China. The
adjustments are concentrated in Chapter 2 “Normative references”. The
specific adjustments are as follows:
● Use GB/T 251 which is equivalent to the international standard to
replace ISO 105-A03 (see4.3);
● Use GB/T 33729 which modifies and adopts international standards to
replace ISO 105-F09 (see 4.2);
● Use GB/T 39364 which modifies and adopts international standards to
replace ISO 2418 (see 5.1);
● Use QB/T 2707 which modifies and adopts international standards to
replace ISO 2419 (see 5.3);
● Delete the reference to ISO 105-A01 and ISO 105-A04 (see Chapter
2 of ISO 20433:2012);
● Add reference to GB/T 6682 (see 4.4);
-- Delete the description about the test for colour fastness in "3 Principle"
(see Chapter 3 of ISO 20433:2012);
-- Add the requirement that the friction head is a cylinder in "4.1 Test device
for colour fastness to crocking" (see 4.1);
-- Delete "4.4 Spectrophotometer or colorimeter for evaluating staining" (see
4.4 of ISO 20433:2012);
-- Add regulations on test water (see 4.4);
-- Add "4.5 Standard light source" (see 4.5);
Leather - Tests for colour fastness - Colour fastness
to crocking
1 Scope
This Standard specifies the method for determining the colour fastness to
crocking of the leather surface by using white cotton cloth to rub the leather
surface repeatedly.
This Standard applies to the test of colour fastness to crocking on the surface
of various types of colored leather.
2 Normative references
The following documents are indispensable for the application of this document.
For dated references, only the dated version applies to this document. For
undated references, the latest edition (including all amendments) applies to this
document.
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 (GB/T 39364-2020, 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
Under specified conditions, rub the leather sample back and forth with the white
cotton cloth (dry or wet) that is placed on the cylindrical friction head; use the
grey scale to assess the staining of the white cotton cloth.
Fix the test surface of the sample upward on the platform of the test device, so
that the length direction of the sample is consistent with the running direction of
the friction head. Carry out the test according to the procedures that are
specified in 6.2 and 6.3.
6.2 Dry friction
Fix the adjusted cotton rubbing cloth (4.2) on the friction head (4.1); make the
warp direction of the cotton rubbing cloth consistent with the running direction
of the friction head, and the friction head in horizontal contact with the leather
sample. Run the device, at a running speed of 1 time/s (1 reciprocating cycle is
1 time), to rub 10 times in total; remove the cotton rubbing cloth after rubbing.
6.3 Wet friction
Weigh the adjusted cotton rubbing cloth (4.2); then, completely immerse it in
water; take it out after a period of time; gently press to squeeze out the water;
re-weigh so that the water absorption rate of the cotton rubbing cloth reaches
(100±5) %; fix it on the friction head (4.1); test according to the provisions of
6.2. After the friction is finished, remove the cotton rubbing cloth and dry it at
room temperature.
7 Result assessment
Use a brush or scotch tape to carefully remove the dust, stains and fibrous
materials remaining on the surface of the cotton rubbing cloth; only consider
the staining of the cotton rubbing cloth due to the color.
Note: During the test, due to the migration of colored substances, such as
coatings, pigments, dyes or dust, color migration which is caused by
other possible reasons on the leather surface, the cotton rubbing cloth is
subject to a certain degree of color pollution.
Place three layers of unused cotton rubbing cloth on the back of each to-be-
assessed cotton rubbing cloth. Under D65 light source, use the grey card for
assessing staining (4.3) to assess the staining grade of the cotton rubbing cloth.
8 Assessment error
The difference between the assessment results of different assessors shall not
be more than half a grade.