GB 251-1995 English PDF

GB 251-1995: Gray scale for assessing staining
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GB 251-1995
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ISO 105/A03-1993
Replacing GB 251-84
Gray scale for assessing staining
ISSUED ON: DECEMBER 08, 1995
IMPLEMENTED ON: MAY 01, 1996
Issued by: State Bureau of Technical Supervision
Table of Contents
1 Subject content and scope of application ... 3 
2 Principles ... 3 
Additional information ... 6 
Gray scale for assessing staining
This standard equivalently adopts the international standard ISO 105/A03-1993
"Textiles - Color fastness test - Gray scale for assessing staining".
1 Subject content and scope of application
This standard specifies the gray scale for assessing the staining of textiles, in the color
fastness test of textiles, as well as its application method. The precise color
measurement interval value of this gray scale can be used, as a permanent record, for
the comparison of newly produced gray scales AND the gray scales that have changed
during storage or use.
2 Principles
2.1 The basic gray scale is composed of five pairs of matt gray or white small-cards
(paper- or cloth-pieces), which are divided into five fastness grades, namely 5, 4, 3, 2,
1, according to the distinguishable color difference. Add half a grade in every two
grades, namely 4-5, 3-4, 2-3, 1-2, to expand it into a five-grade nine-level gray scale.
The first composition of each pair is white, in which only the second composition of
color fastness grade 5 is consistent with the first composition; the second composition
of other pairs becomes deeper in turn, AND the color difference gradually increases.
All grades of color differences are determined by colorimeter; the entire chromaticity
is specified as follows.
2.2 Pieces of paper or cloth shall be of white or neutral gray color. It shall be measured
using a spectrophotometer with specular component. Chromaticity data are calculated,
using the Chromaticity system (10° field of view) and D65 luminosity, in the CIE 1964
supplementary standard.
2.3 The tristimulus value Y of the first composition of each pair shall be not lower than
85.
2.4 The color difference, between the second composition and the first composition of
each pair, is specified as follows:
GB 251-1995
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ISO 105/A03-1993
Replacing GB 251-84
Gray scale for assessing staining
ISSUED ON: DECEMBER 08, 1995
IMPLEMENTED ON: MAY 01, 1996
Issued by: State Bureau of Technical Supervision
Table of Contents
1 Subject content and scope of application ... 3 
2 Principles ... 3 
Additional information ... 6 
Gray scale for assessing staining
This standard equivalently adopts the international standard ISO 105/A03-1993
"Textiles - Color fastness test - Gray scale for assessing staining".
1 Subject content and scope of application
This standard specifies the gray scale for assessing the staining of textiles, in the color
fastness test of textiles, as well as its application method. The precise color
measurement interval value of this gray scale can be used, as a permanent record, for
the comparison of newly produced gray scales AND the gray scales that have changed
during storage or use.
2 Principles
2.1 The basic gray scale is composed of five pairs of matt gray or white small-cards
(paper- or cloth-pieces), which are divided into five fastness grades, namely 5, 4, 3, 2,
1, according to the distinguishable color difference. Add half a grade in every two
grades, namely 4-5, 3-4, 2-3, 1-2, to expand it into a five-grade nine-level gray scale.
The first composition of each pair is white, in which only the second composition of
color fastness grade 5 is consistent with the first composition; the second composition
of other pairs becomes deeper in turn, AND the color difference gradually increases.
All grades of color differences are determined by colorimeter; the entire chromaticity
is specified as follows.
2.2 Pieces of paper or cloth shall be of white or neutral gray color. It shall be measured
using a spectrophotometer with specular component. Chromaticity data are calculated,
using the Chromaticity system (10° field of view) and D65 luminosity, in the CIE 1964
supplementary standard.
2.3 The tristimulus value Y of the first composition of each pair shall be not lower than
85.
2.4 The color difference, between the second composition and the first composition of
each pair, is specified as follows: