GB/T 17644-2008 English PDF (GBT17644-2008)

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GB/T 17644-2008: Test method for whiteness and chromaticity of textile fibres
GB/T 17644-2008
GB
NATIONAL STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 59.060
W 04
Replacing GB/T 17644-1998
Test method for whiteness
and chromaticity of textile fibres
ISSUED ON. AUGUST 7, 2008
IMPLEMENTED ON. DECEMBER 1, 2008
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China;
Standardization Administration of the People’s Republic of
China.
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Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Principle... 5 
5 Instruments ... 5 
6 Standard atmospheres for pre-conditioning, conditioning and testing ... 6 
7 Test samples ... 6 
8 Test steps ... 6 
9 Test results ... 7 
10 Test report ... 9 
Annex A (Normative) Sample case ... 10 
Annex B (Normative) Calculation equation for the L*, a*, b* system of the
International Chromaticity Society ... 11 
Annex C (Normative) Calculation equation of color difference ... 13 
Annex D (Informative) Calculation examples for the whiteness and
chromaticity of textile fibres ... 15 
Foreword
This Standard replaces GB/T 17644-1998 Test method for whiteness and
chromaticity of textile fibres.
Compared with GB/T 17644-1998, the major changes in this Standard are as
follows.
a) CHANGE the “color difference meter” into the “spectrophotometric
colorimeter”;
b) ADD the terms of “chromaticity” and “colour hue”;
c) EXPAND the standard’s scope of application;
d) MODIFY the contents of Annex A;
e) MODIFY the calculation equations in the text as well as Annexes B and C
in accordance with the latest release of CIE regulations; and
f) ADD the corrected value of the color difference based on the L*, a* and b*
calculated according to the tristimulus values X, Y, Z.
Annexes A, B and C of this Standard are normative annexes, while Annex D is
informative annex.
This Standard was proposed by and shall be under the jurisdiction of the China
Fibre Inspection Bureau.
Major drafting organizations of this Standard. Xi’an Polytechnic University, and
China Fibre Inspection Bureau.
Main drafters of this Standard. Sun Runjun, Chen Meiyu, Feng Ping, Lai Kan
and Xu Jun.
This Standard was first released in 1998. This is the first revision.
Test method for whiteness
and chromaticity of textile fibres
1 Scope
This Standard specifies the test methods for determining the whiteness and
chromaticity of textile fibres by using a spectrophotometric colorimeter.
This Standard is applicable to the determination of the whiteness and
chromaticity of textile fibres.
2 Normative references
The provisions in the following documents become the provisions of this
Standard through reference in this Standard. For dated references, the
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, parties who reach an agreement based on this
Standard are encouraged to study if the latest editions of these documents are
applicable. For undated references, the latest editions apply to this Standard.
GB/T 3979 Methods of measuring the colour of materials
GB 6529 Standard atmospheres for textiles conditioning and testing
GB/T 8170 Rules of rounding off for numerical values
3 Terms and definitions
The following terms and definitions are applicable to this Standard.
3.1 Tristimulus values X, Y, Z
It refers to the three reference stimuli or three matching stimuli required to
match with the studied color stimulus in the D65 light source, 10° visual standard
and tristimulus system in CIE 1994.
3.2 Index of lightness L*
It refers to the brightness coordinates in the 3D Cartesian coordinate system of
L*, a*, b* uniform chromaticity space.
3.3 Chromaticity coefficient a*, b*
It refers to the values in the 3D Cartesian coordinate system of L*, a*, b* uniform
chromaticity space, among which a* positive value is in red, a* negative value
is in green, b* positive value is in yellow, and b* negative value is in blue.
3.4 Chromaticity
It refers to the two-dimensional quantitative value of the color represented by
the chromaticity coordinates, which can be a*, b* (Cartesian coordinates) or C*,
H* (polar coordinates).
3.5 Whiteness W
It refers to the one-dimensional evaluation on the white degree of the white
substance surface.
3.6 Chroma saturation C*
Reflected chromatic light is a mixture of colored light and white light. Chroma
saturation refers to the proportion of colored light in total reflectance, which is
the value of the radius in the polar coordinate system.
3.7 Colour hue (angle) H*
It refers to the value of the direction angle of the colour hue in the polar
coordinate system.
4 Principle
USE a spectrophotometric colorimeter to directly measure the tristimulus values
X, Y, Z of the test sample with a certain compression density on the
transmission surface of the test case, and thus OBTAIN the chromaticity and
whiteness values by calculation.
5 Instruments
5.1 Colorimeter
The spectrophotometric colorimeter used in this Standard shall meet the
following technical conditions.
a) Diameter () of the measurement window. 20mm to 30mm;
b) Lighting source. D65 light source;
c) 10° viewing angle;
9.2 Whiteness index of textile fibres
9.2.1 The whiteness value shall be calculated according to the Equation (7).
Where.
W - Whiteness, %.
The calculation results shall be rounded off to four decimal places according to
the provisions of GB/T 8170.
9.2.2 In the L*, a*, b* index system, a*, b* represent the color cast direction of
whiteness. a* positive value indicates reddish, a* negative value indicates
greenish, b* positive value indicates yellowish, and b* negative value indicates
bluish.
9.3 Color difference index of textile fibres
During the calculation of color difference against the standard sample, the color
difference shall be calculated in accordance with the Annex C. SEE Annex D
for specific calculation examples.
10 Test report
The test report shall include the following contents.
a) serial number of the executive standard;
b) sample name, specifications, batch number, quantity and status, and
sample delivery agency;
c) test date and environmental conditions;
d) model and major technical conditions of the test instrument;
e) test results;
f) remarks; and
g) testers.
Annex D
(Informative)
Calculation examples for the whiteness and chromaticity of textile fibres
D.1 Calculation examples for the whiteness of textile fibres
The colorimeter shall be X0 = 95.045, Y0 = 100.000 and Z0 = 108.255, under
the conditions of D65 light source, 10° viewing angle and 0/d.
The tristimulus values of some batch of white samples measured under the
conditions of D65 light source, 10° viewing angle and 0/d are.
CALCULATE.
CALCULATE L* according to the Equation (1).
CALCULATE a* according to the Equations (3), (B.4) and (B.6).
CALCULATE b* according to the Equations (4), (B.6) and (B.8).
PUT the L*, a* and b* calculation results in the Equation (7) to calculate W.
Test results. The whiteness of the fibre sample is 76.578 0%; a* = +0.115 6,
reddish; b* = +11.531 6, yellowish, which is yellowish orange.