Standards related to:

GB/T 17644-2008**GB/T 17644-2008: PDF in English (GBT 17644-2008) **

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.

3. No action is required - Full-copy of this standard will be automatically &

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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.

......

Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.