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GB/T 8427-2019 English PDF (GBT8427-2019)

GB/T 8427-2019 English PDF (GBT8427-2019)

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GB/T 8427-2019: Textiles -- Tests for color fastness -- Color fastness to artificial light: Xenon arc

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.
GB/T 8427-2019
GB
NATIONAL STANDARD OF THE
PEOPLE 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 t...

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