GB/T 8427-2019 PDF in English
GB/T 8427-2019 (GB/T8427-2019, GBT 8427-2019, GBT8427-2019)
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Textiles -- Tests for color fastness -- Color fastness to artificial light: Xenon arc
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| GB/T 8427-2008 | English | 105 |
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Textiles -- Tests for color fastness -- Color fastness to artificial light: Xenon arc fading lamp test
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| GB/T 8427-1998 | English | 439 |
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Textiles--Tests for colour fastness--Colour fastness to artificial light: Xenon arc fading lamp test
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Textiles--Testing method for colour fastness to light: Xenon arc
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Standards related to (historical): GB/T 8427-2019
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GB/T 8427-2019: PDF in English (GBT 8427-2019) GB/T 8427-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.080.01
W 04
Replacing GB/T 8427-2008
Textiles - Tests for color fastness - Color fastness to
artificial light: Xenon arc
(ISO 105-B02:2014, Textiles - Tests for color fastness - Part B02: Color
fastness to artificial light: Xenon arc fading lamp test, MOD)
ISSUED ON: DECEMBER 31, 2019
IMPLEMENTED ON: JULY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 8
4 Principle ... 9
5 Reference materials and apparatus ... 10
5.1 Reference materials ... 10
5.2 Apparatus ... 11
6 Preparation of test specimens ... 13
7 Exposure conditions ... 14
8 Procedure ... 15
8.1 Apparatus set-up ... 15
8.2 Adjustment of the effective humidity (see Clause 7 and Annex E) ... 15
8.3 Exposure methods ... 17
9 Assessment of color fastness to light ... 26
10 Test report ... 28
Annex A (Informative) General information on color fastness to light ... 31
Annex B (Informative) Light exposure equivalents for blue wool references L2
to L9 ... 34
Annex C (Normative) Requirements for xenon arc lamp exposure devices ... 35
Annex D (Normative) Procedures for measuring the irradiance uniformity in the
specimen exposure area (for apparatus manufacturers only) ... 39
Annex E (Informative) Guidelines for conducting testing ... 42
Bibliography ... 54
Textiles - Tests for color fastness - Color fastness to
artificial light: Xenon arc
1 Scope
This Standard specifies a method intended for determining the effect on the
color fastness of textiles of all kinds and in all forms to the action of an artificial
light source representative of natural daylight (D65).
This Standard is applicable to colored textiles; is also applicable to white
(bleached or optically brightened) textiles.
Note: This Standard allows the use of two different sets of blue wool references. The
results may not be identical.
2 Normative references
The following documents are indispensable for the application of this document.
For the dated references, only the editions with the dates indicated are
applicable to this document. For the undated references, the latest edition
(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 730 Textiles - Tests for colour fastness - Quality control of Blue wool
reference materials 1 to 7 (GB/T 730-2008, ISO 105-B08:1995, MOD)
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 8431 Textiles - Tests for colour fastness - Detection and assessment
of photochromism (GB/T 8431-1998, eqv ISO 105-B05:1994)
GB/T 32616 Textiles - Tests for colour fastness - Instrumental assessment of
change in colour for determination of grey scale rating (GB/T 32616-2016,
ISO 105-A05:1996, MOD)
FZ/T 01047 Standard light sources and conditions for visual assessment of
Data in Annex B are presented to illustrate the relationship of each of the blue
wool references on exposure to fixed amounts of radiant energy.
5.1.4 Humidity-test control
The effective humidity can only be measured by determining the color fastness
to light of a specific humidity-test control fabric (see 3.7).
5.2 Apparatus
5.2.1 Light source
5.2.1.1 The exposure device shall provide for placement of specimens and any
sensing devices in positions that allow uniform irradiance from the light source.
The spectral irradiance produced in an artificial accelerated light and
weathering device is very important. Ideally, the relative spectral irradiance
produced by the device should be a very close match to that of solar radiation,
especially in the short wavelength UV region. Annex C provides information
about important benchmark solar spectra that can be used for comparing the
spectral irradiance produced in the artificial accelerated exposure to that for
solar radiation.
5.2.1.2 Exposure devices shall be designed such that the variation in irradiance
at any location in the area used for specimen exposure shall not exceed ± 10 %
of the mean. Procedures for measuring irradiance uniformity are found in Annex
D.
Note: The irradiance uniformity in exposure devices depends on several factors. The
configuration of the xenon arc lamp with respect to the specimens on exposure,
including the differences in distance between the lamp(s) and the samples can affect
uniformity of exposure. Deposits which can develop on the optical system and
chamber walls, and the type and number of specimens being exposed, can also
have an effect on uniformity of exposure.
5.2.1.3 Periodic repositioning of the test specimens in the test chamber is
recommended to ensure the most consistent results.
5.2.1.4 Follow the apparatus manufacturer’s instructions for lamp and filter
replacement.
Direct radiation from xenon burners contains considerable amounts of short-
wavelength ultraviolet radiation not present in daylight. Optical filters shall be
fitted to minimize short-wavelength light (less than 310 nm) in accordance with
the requirements in Annex C. The xenon arc, when appropriately filtered,
produces radiation with a spectral power distribution that is a good simulation
5.2.3 Humidity
The presence of moisture can have a significant effect in accelerated laboratory
exposure tests. The apparatus shall have the means for providing and
controlling moisture to specimens by humidification of the chamber air. The
quality of the water used to create the effective humidity shall be a minimum of
Grade 3 in accordance with GB/T 6682.
5.2.4 Covers
Covers shall be made from thin opaque material, for example high-grade steel,
thin sheet aluminium or cardboard covered with aluminium foil, for partial
covering of samples and blue wool references. The opaque material shall
neither react with the test specimens nor the test conditions and shall not itself
produce any change in color of either the test specimen or the reference
materials.
5.2.5 Assessment light source
It shall meet the requirements of FZ/T 01047.
5.2.6 Assessment cabinet
It shall meet the requirements of GB/T 6151.
5.2.7 White card stock
It shall not contain fluorescent brightening agent.
5.2.8 Assessment mask
It shall meet the requirements of GB/T 6151. In order to obtain reliable test
results, the test specimen(s) shall be masked with a material that is identical in
color to the sleeve that is used to mask the grey scale (5.2.9).
5.2.9 Grey scale for assessing change in color
It shall meet the requirements of GB/T 250.
6 Preparation of test specimens
6.1 The size of the test specimen will depend on the number of specimens to
be tested and on the shape and dimensions of the specimen holders supplied
with the apparatus. Attention is drawn to the guidelines given in E.4.
6.2 The specimen may be a strip of cloth, yarn wound close together on a white
reference as referenced in Table 2. The contrast should be equal to that
specified for the appropriate exposure conditions (see Table 2).
8.2.7 If the necessary contrast in 8.2.6 is not achieved, adjust the apparatus to
give the required selected exposure conditions and repeat 8.2.3 to 8.2.6.
8.3 Exposure methods
8.3.1 General
There are five separate methods given. The user should select the most
appropriate method for their application.
For Methods 1 to 4, assessment of fading of test specimens or reference
samples is critical to obtaining valid results. It is not sufficient to rely on
exposure time (hours) to determine the end point of the various stages of each
method. For Method 5, the end point is determined by a specified dosage of
irradiance and intermediate assessment of fading may not be required.
Attention is drawn to the guidelines given in the annexes in relation to selection
of apparatus, test method, and to the recommendations on good testing
practice for different types of textile materials.
8.3.2 Method 1
8.3.2.1 This method is considered the most informative and should be used in
cases of dispute. The basic feature is the control of the exposure period by
inspection of the specimen, and one set of blue wool references is required for
each specimen under test. This method is especially suitable for determination
of color fastness to light for test specimens of unknown performance.
For this method, opaque covers (5.2.4) masking one-third and two-thirds of the
test specimens and blue wool references are required.
8.3.2.2 Arrange the test specimen and the blue wool references on the white
card stock (5.2.7) in accordance with Clause 6 and as shown in Figure 2. Cover
the middle one-third of the test card using an opaque cover (5.2.4) ABCD.
The blue wool references and test specimen need not necessarily be mounted
on the same card and where applicable test cards should be mounted in
suitable specimen holders.
8.3.2.6 For white (bleached or optically brightened) test specimens, terminate
the exposure at this point and carry out the assessment of color fastness as
described in Clause 9.
8.3.2.7 For all other test specimens, apply another opaque cover (5.2.4) FBCE
(see Figure 2) to mask the test specimen and blue wool reference such that the
right-hand one-third of the test card(s) remains exposed. It is preferable to
replace cover ABCD with a new cover FBCE in order to avoid undesired effects
from light seepage. If a cover ADEF is added, then the additional cover should
be of sufficient dimensions to overlap the existing cover and prevent any light
seepage along the line A–D.
8.3.2.8 Replace the masked card in the test chamber and continue to expose
until the contrast between the exposed and unexposed portions of the test
specimen is equal to grey scale grade 3 (5.2.9) (second period).
8.3.2.9 If blue wool reference 7 (or L7) fades to a contrast equal to grey scale
grade 4 (5.2.9) before the test specimen does, the exposure is terminated at
this stage. When a specimen has a color fastness equal to or greater than 7 (or
L7) it would require unduly long exposure to produce a contrast equal to grey
scale grade 3; moreover this contrast would be impossible to obtain when the
color fastness is 8 (or L8). Assessments in the region of 7~8 (or L7~L8) are
made, therefore, when the contrast produced on blue wool reference 7 (or L7)
is equal to grey scale grade 4, the time required to produce this contrast being
long enough to eliminate any error which might result from inadequate exposure.
8.3.3 Method 2
8.3.3.1 This method may be used when a large number of specimens have to
be tested simultaneously. The feature is the control of the exposure periods by
inspection of the blue wool references, which allows a number of specimens
differing in color fastness to be tested against a single set of blue wool
references, thus conserving supplies of the references. This method is
especially suitable for the dyestuff industry.
For this method, opaque covers masking approximately one-quarter, one-half
and three-quarters of the test specimens and blue wool references are required
(5.2.4).
8.3.3.2 Arrange the test specimens and the blue wool references as required,
in accordance with Clause 6; more than one white card stock may be necessary.
As shown in Figure 3, apply opaque cover (5.2.4) ABCD to mask the left-hand
most quarter of the total width of each specimen and blue wool references.
undesired effects of light seepage. If a cover BEFC is added, then the additional
cover should be of sufficient dimensions to overlap the existing cover and
prevent any light seepage along the line B–C.
8.3.3.6 Continue to expose until a contrast between the exposed (EGHF) and
unexposed (ABCD) areas in blue wool reference 6 or L5 equal to grey scale
grade 4 (5.2.9) is achieved (second period); then replace the cover with one
that masks the area AGHD (see Figure 3).
It is preferable to replace cover AEFD with a new cover AGHD in order to avoid
undesired effects of light seepage. If a cover EGHF is added, then the additional
cover should be of sufficient dimensions to overlap the existing cover and
prevent any light seepage along the line E–F.
8.3.3.7 Continue to expose until whichever of the following conditions occurs
first, either (third period):
a) a contrast between the exposed and unexposed areas on blue wool
reference 7 or L7 equal to grey scale grade 4 (5.2.9); or
b) a contrast between the exposed and unexposed areas equal to grey scale
grade 3 (5.2.9) on the most resistant specimen; or
c) for white (bleached or optically brightened) textiles, a contrast between the
exposed and unexposed areas equal to grey scale grade 4 (5.2.9) on the
most resistant specimen.
Note: The contrast referred to in b) and c) may occur before 8.3.3.5 or 8.3.3.6 has taken
place and therefore the end point has been achieved.
8.3.4 Method 3
8.3.4.1 This test method is similar to Method 1 but is suitable where the test
specimen is compared for conformity with a known performance specification.
The feature is the control of exposure by inspection of the target blue wool
reference. The method allows multiple test specimens to be tested using a
reduced number of blue wool references, typically the target blue wool
reference together with the two blue wool references immediately preceding the
target blue wool reference. This is to assist in quantifying the color fastness
grade of a specimen which does not conform with the required performance
specification.
For this method, opaque covers masking approximately one-third and two-
thirds of the test specimens and blue wool references are required (5.2.4).
8.3.4.2 Arrange one or more test specimens together with relevant blue wool
8.3.6.3 Set the apparatus according to the manufacturer’s instructions to
provide the desired level of irradiance (see 5.2.1.5.2).
8.3.6.4 Place the masked card in the test chamber and expose the masked card
to light under the selected exposure conditions in Table 2 until the desired level
of radiant energy normally expressed in Joules has been achieved.
9 Assessment of color fastness to light
9.1 To avoid a mis-rating of the color fastness of the specimen due to its
photochromism (3.8), the tested specimen cards should be allowed to condition
in the dark at ambient indoor conditions for 24 h before assessing the color
fastness (see GB/T 8431).
For Method 1, based on the contrasts equal to grey scale grade 4 and grey
scale grade 3 (5.2.9) between exposed and unexposed portions of the test
specimen, the final assessment (reported grade) of color fastness to light is
given. For white (bleached or optically brightened) textiles, the final assessment
of color fastness grade to light is based on a contrast equal to grey scale grade
4 between exposed and unexposed portions of the test specimen.
9.2 Remove all the covers (5.2.4), thus revealing on the test specimens and
blue wool references the various areas, which have been exposed for different
times, which will depend on the method used, together with the area which has
not been exposed to light.
Comparison of the changes in the test specimen with changes in the blue wool
references shall be facilitated by surrounding the specimen with an assessment
mask (5.2.8).
Compare the change in color of the specimen with the corresponding changes
in the blue wool references using the assessment cabinet (5.2.6) under D65
(artificial daylight) illuminant (see GB/T 6151). The use of alternative illuminants
shall be agreed between the parties and shall be reported.
For all methods using blue wool references, the color fastness of the specimen
is the number of the blue wool reference which shows similar changes in color
(visual contrast between exposed and unexposed parts of the specimen). If the
specimen shows changes in color which are near to the imaginary reference
midway between any two consecutive blue wool references, an intermediate
rating, for example 3-4 or L2-L3, shall be given. Assessments shall be confined
to whole or midway ratings only.
Assessments of change in color are made at different exposure periods as
defined in the relevant method. For Methods 1, 3 and 4 this will give two
“satisfactory”; if the specimen shows a greater change in color than the
reference sample, the color fastness shall be classified “unsatisfactory”.
9.9 Exposures based on an agreed-upon radiant energy level (see Method 5)
are assessed either by comparison against the grey scale (5.2.9) for assessing
change in color, in accordance with GB/T 250, or by comparison of the change
in color of the sample with that of the blue wool references similar to 9.2.
10 Test report
The test report shall include the information:
a) the test is carried out according to this Standard.
b) all details necessary for the specimens tested;
c) for Methods 1 and 2:
report the numerical rating for the color fastness to light. The color
fastness rating shall be expressed either:
1) by the numerical mean of the color fastness provided that the difference
between the individual assessments of the periods does not exceed
one half grade (together with the prefix L when using the blue wool
references designated L2 to L9); or
2) by the mean color fastness to light reported together with the
assessment result of each period where the difference between the
individual assessments of the periods exceeds one half grade (together
with the prefix L when using the blue wool references designated L2 to
L9).
If this rating is equal to or higher than 4 or L3 and the preliminary
assessment is equal to or lower than 3 or L2, report the latter figure in
brackets.
d) for Method 3:
report the numerical rating for the color fastness to light. The color
fastness rating shall be expressed either:
1) by the mean assessment result of color fastness to light provided that
the difference between the individual assessments of the periods does
not exceed one half grade (together with the prefix L when using the
blue wool references designated L2 to L9); or
Annex A
(Informative)
General information on color fastness to light
When in use, textiles are usually exposed to light. Light tends to destroy coloring
matters and the result is the well-known defect of “fading”, whereby colored
materials change color - usually becoming paler and duller. Dyes used in the
textile industry vary enormously in their reaction to light and it is obvious that
there must be some method of measuring their fastness. The substrate also
influences the color fastness of a dye to light.
This Standard cannot satisfy completely all the interested parties (who range
from dye manufacturers and the textile industry to wholesale and retail traders
and the general public) without becoming technically involved and possibly
difficult to understand by many who have a direct interest in its application.
The following non-technical description of a test has been prepared for the
benefit of those who find the detailed technicalities of this Standard difficult to
understand. The method is to expose the specimen being tested and to expose
also, at the same time and under the same conditions, a series of color fastness
references which are pieces of wool cloth dyed with blue dyes of different
degrees of fastness. When the specimen has faded sufficiently, it is compared
with the references and if it has behaved, for instance, like reference 4 then its
color fastness is said to be 4.
The color fastness references should cover a wide range, since some
specimens fade noticeably after exposure for 2 h~3 h to bright summer
sunshine, although others may withstand exposure for several years without
change, the dyes in fact outliving the material to which they have been applied.
Eight references have been chosen, reference 1 being the most fugitive and
reference 8 the most resistant. If it takes a certain length of time for reference
4 to fade under certain conditions, then the same amount of fading will occur
on reference 3 in approximately half the time, or on reference 5 in approximately
twice that time, provided that the conditions are the same.
It is necessary to ensure that different people testing the same material will fade
it to the same extent before assessment against the simultaneously faded
reference. The ultimate users of dyed materials differ widely in what they
consider to be “faded articles” and therefore specimens under test are faded to
two different degrees which adequately cover most opinions and make
assessment more reliable. These required degrees of fading are defined by
Annex C
(Normative)
Requirements for xenon arc lamp exposure devices
C.1 General requirements
The xenon arc lamp exposure device uses one or more water or air cooled
xenon arc lamps. The lamps may differ in size and wattage, depending on the
design or capacity of the exposure area. The device shall be equipped with
filters that remove unrealistic short wavelength ultraviolet radiation and
optionally filters that remove or reduce infrared radiation that could contribute
to high specimen temperatures. In addition, the device shall provide for
placement of specimens and any sensing devices in positions that allow
uniform irradiance from the light source.
The xenon arc lamp exposure device shall include means to place specimen
holders in an area of uniform irradiance. This may be a revolving rack that
rotates around a vertically mounted xenon arc lamp or lamps. The revolving
rack may include means to turn the specimen holders about their vertical axis
with each revolution of the rotating specimen rack and this is referred to as “flip-
flop” mode (3.9). Regardless of the use of flip-flop mode, the exposure of the
test specimens to the light source is considered to be continuous. The device
may also use a flat tray on which the specimen holders are mounted. This flat
tray shall be located parallel to the xenon arc lamp or lamps.
The xenon arc lamp exposure device shall be closed operated, to prevent
operators from being exposed to UV radiation. In addition, the device is typically
enclosed and insulated, to minimize the effects of variation in room temperature.
C.2 Light source
The light source shall consist of a xenon arc lamp of correlated color
temperature 5500 K to 6500 K, the size of which will depend on the type of
apparatus used. The xenon arc lamp shall use filters that provide a simulation
of solar radiation filtered by window glass. The transmission of the filter system
used shall be at least 90 % between 380 nm and 750 nm, falling to 0 between
310 nm and 320 nm. Infrared radiation from the xenon arc may be attenuated
by use of filters to allow better control of the sample temperature.
Note: The irradiance uniformity in exposure devices depends on several factors such as
deposits which can develop on the optical system and chamber walls, the type and
number of specimens being exposed.
required level of radiant exposure.
C.3 Temperature
The surface temperature of exposed specimens depends primarily on the
amount of radiation absorbed, the emissivity of the specimen, the amount of
thermal conduction within the specimen and the amount of heat transmission
between the specimen and the air or between the specimen and the specimen
holder. Since it is not practical to monitor the surface temperature of individual
test specimens, a specified black-coated sensor is used to measure and control
the temperature within the test chamber. The temperature sensor fixed to a
black plate shall be mounted within the specimen exposure area so that it
receives the same radiation and experiences the same cooling conditions as a
flat test panel surface.
Two types of black-coated temperature sensor may be used:
Black-standard thermometers consist of a plane (flat) stainless-steel plate with
a thickness of about 0.5 to 1.2 mm. A typical length and width is about 70 mm
by 40 mm. The surface of this plate facing the light source shall be coated with
a black layer which has good resistance to ageing. The coated black plate shall
absorb at least 90 % of all incident flux to 2500 nm. A thermally sensitive
element such as a platinum resistance sensor shall be attached in good thermal
contact to the centre of the plate on the side opposite the radiation source. This
side of the metal plate shall be attached to a 5 mm thick baseplate made of
unfilled poly(vinylidene fluoride) (PVDF). A small space sufficient to hold the
platinum resistance sensor shall be machined in the PVDF baseplate. The
distance between the sensor and this recess in the PVDF plate shall be about
1 mm. The length and width of the PVDF plate shall be sufficient so that no
metal-to-metal thermal contact exists between the black-coated metal plate of
black-standard thermometer and the mounting holder into which it is fitted. The
metal mounts of the holder of the insulated black panel shall be at least 4 mm
from the edges of the metal plate.
Black-panel thermometers, consist of a plane (flat) metal plate that is resistant
to corrosion. Typical dimensions are about 150 mm long, 70 mm wide and 1
mm thick. The surface of this plate that faces the light source shall be coated
with a black layer which has good resistance to ageing. The coated black plate
shall absorb at least 90 % of all incident flux to 2500 nm. A thermally sensitive
element shall be firmly attached to the centre of the exposed surface. This
thermal sensitive element can be a black-coated stem-type bimetallic dial
sensor, a resistance based sensor, a thermistor, or thermocouple. The back of
the black panel thermometer shall be open to the atmosphere within the
exposure chamber.
Annex E
(Informative)
Guidelines for conducting testing
E.1 Selection of apparatus
This method permits the use of a wide variety of testing machines including
carousel-type machines and flat-bed machines. In addition individual machines
may have further options such as the use of alternate cycle rotation of test
specimens (“flip-flop” mode).
The choice of testing machine will in part depend upon the size, type, volume
of test specimens and throughput of the testing machine. For example, a
carousel type machine without irradiance control in which test specimens are
constantly exposed to the light source will have half the potential capacity of the
same machines with double sided specimen holders and using flip-flop mode.
However, c......
......
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