ASTM D7869-13
(Practice)Standard Practice for Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings
Standard Practice for Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings
SIGNIFICANCE AND USE
5.1 This test procedure is used to simulate the physical and environmental stresses that a coating for exterior transportation applications (for example, automotive) is exposed to in a subtropical climate, such as southern Florida. It has been found that such a subtropical climate causes particularly severe deterioration of such coatings. The long water exposures and wet/dry cycling found in southern Florida are particularly important for this deterioration, in addition to the high dosage of solar radiation (3). This practice was developed to address the deficiencies of historical tests used for transportation coatings, especially automotive coatings (4).Note 1—This test procedure was developed through eight years of cooperative testing between automotive and aerospace OEM’s, material suppliers, and test equipment manufacturers. See References for published papers on this research.
SCOPE
1.1 This practice specifies the operating procedures for a controlled irradiance xenon arc light and water apparatus. The procedure uses one or more lamp(s) and optical filter(s) to produce irradiance similar to sunlight in the UV and visible range. It also simulates the water absorption and stress cycles experienced by automotive exterior coatings under natural weathering conditions. This practice has also been found applicable to coatings on other transportation vehicles, such as aircraft, trucks and rail cars.
1.2 This practice uses a xenon arc light source with specified optical filter(s). The spectral power distribution (SPD) for the lamp and special daylight filter(s) is as specified in Annex A1. The irradiance level used in this practice varies between 0.40 and 0.80 W/(m2·nm) at 340 nm. Water is sprayed on the specimens during portions of several dark steps. The application of water is such that the coatings will absorb and desorb substantial amounts of water during testing. In addition, the cycling between wet/dry and warm/cool will induce mechanical stresses into the materials. These test conditions are designed to simulate the physical and chemical stresses from environments in a subtropical climate, such as southern Florida.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D7869 − 13
Standard Practice for
Xenon Arc Exposure Test with Enhanced Light and Water
Exposure for Transportation Coatings
This standard is issued under the fixed designation D7869; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice specifies the operating procedures for a 2.1 ASTM Standards:
controlled irradiance xenon arc light and water apparatus. The D4517 Test Method for Low-Level Total Silica in High-
procedure uses one or more lamp(s) and optical filter(s) to Purity Water by Flameless Atomic Absorption Spectros-
produce irradiance similar to sunlight in the UV and visible copy
range. It also simulates the water absorption and stress cycles G113 Terminology Relating to Natural andArtificial Weath-
experienced by automotive exterior coatings under natural ering Tests of Nonmetallic Materials
weathering conditions. This practice has also been found G147 Practice for Conditioning and Handling of Nonmetal-
applicable to coatings on other transportation vehicles, such as lic Materials for Natural and Artificial Weathering Tests
aircraft, trucks and rail cars. G151 Practice for Exposing Nonmetallic Materials inAccel-
erated Test Devices that Use Laboratory Light Sources
1.2 This practice uses a xenon arc light source with speci-
G155 Practice for Operating XenonArc LightApparatus for
fied optical filter(s). The spectral power distribution (SPD) for
Exposure of Non-Metallic Materials
the lamp and special daylight filter(s) is as specified in Annex
A1. The irradiance level used in this practice varies between
3. Terminology
0.40 and 0.80 W/(m ·nm) at 340 nm. Water is sprayed on the
3.1 Definitions applicable to this standard can be found in
specimens during portions of several dark steps. The applica-
Terminology G113.
tion of water is such that the coatings will absorb and desorb
3.2 transportation coatings, n—exterior coatings used for
substantial amounts of water during testing. In addition, the
vehicles subjected to natural weathering conditions such as
cycling between wet/dry and warm/cool will induce mechani-
automobiles, aircraft, trucks, rail cars, etc.
cal stresses into the materials. These test conditions are
designed to simulate the physical and chemical stresses from
4. Summary of Practice
environments in a subtropical climate, such as southern
4.1 Test specimens are exposed to specific test conditions
Florida.
designed to simulate the physical and chemical stresses from
1.3 The values stated in SI units are to be regarded as
environments in a subtropical climate, such as southern
standard. No other units of measurement are included in this
Florida. The test conditions consist of a primary test cycle and
standard.
a sub-cycle. The primary test cycle includes two long water
1.4 This standard does not purport to address all of the
exposures and a single, long light exposure with precise
safety concerns, if any, associated with its use. It is the
spectral match to daylight as described in Annex A1.Itis
responsibility of the user of this standard to establish appro-
designed to reproduce water penetration failures, such as
priate safety and health practices and determine the applica-
adhesion, blistering and diffusion of small molecules (1). The
bility of regulatory limitations prior to use.
sub-cycle consisting of shorter alternating water and light
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction of ASTM Committee D01 on Paint and contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Related Coatings, Materials, and Applications and is the direct responsibility of Standards volume information, refer to the standard’s Document Summary page on
Subcommittee D01.27 on Accelerated Testing. the ASTM website.
Current edition approved June 1, 2013. Published June 2013. DOI: 10.1520/ The boldface numbers in parentheses refer to the list of references at the end of
D7869-13. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7869 − 13
exposures is designed to simulate cyclic stresses such as and at least once per year thereafter. Follow the recommenda-
cracking and surface erosion.These two cycles are designed to tions of the manufacturer of the xenon arc light and water
replicatethecommontypesoffailuresdrivenbytheinteraction apparatus for additional checks, if any.
ofphoto-oxidationduringdaylightandhydrolysisduringwater
8.4 Fit the xenon arc light and water apparatus with a
exposure that are seen in a subtropical climate such as gloss
specialdaylightfilter(s)inaccordancewiththerequirementsof
loss, color change, adhesion, blistering and cracking (2).
Annex A1.
NOTE 3—Contact the xenon arc light and water apparatus manufacturer
5. Significance and Use
for the proper optical filter(s) required. Follow the manufacturer’s
recommendations for optical filter maintenance.
5.1 This test procedure is used to simulate the physical and
environmentalstressesthatacoatingforexteriortransportation 8.5 Other optical filters may be used by mutual agreement
between the contractual parties.
applications (for example, automotive) is exposed to in a
NOTE 4—Minor differences in the resultant spectral power distribution
subtropicalclimate,suchassouthernFlorida.Ithasbeenfound
(especially in the short wavelength UV region) can have an impact on the
that such a subtropical climate causes particularly severe
test results. Follow the manufacturer’s recommendations for xenon arc
deterioration of such coatings. The long water exposures and
lamp and optical filter maintenance (5).
wet/dry cycling found in southern Florida are particularly
9. Test Procedure
important for this deterioration, in addition to the high dosage
of solar radiation (3). This practice was developed to address
9.1 Refer to Practice G147 for specimen preparation, con-
the deficiencies of historical tests used for transportation
ditioning and handling. All test specimens must be clean and
coatings, especially automotive coatings (4).
free from fingerprints or other surface contaminants before
NOTE 1—This test procedure was developed through eight years of
testing. Prepare a specimen for exposure to fit the specimen
cooperative testing between automotive and aerospace OEM’s, material
mounting fixture being used, if any. Follow the manufacturers’
suppliers,andtestequipmentmanufacturers.SeeReferencesforpublished
guidelines for specimen size and mounting.
papers on this research.
9.1.1 Sealanycutedgesonthetestspecimensifrequired,as
6. Apparatus agreed between contractual parties. For example, (a) rust and
corrosion products from the cut edges of metal panels may
6.1 The xenon arc light and water apparatus shall comply
stain the test specimens, (b) by-products from the cut edges of
with Practice G155.
plastic substrates may leach out and contaminate test
6.1.1 The xenon arc light and water apparatusshallhavean
specimens, and (c) other panels may not require any edge
uninsulated black panel thermometer as described in Practice
sealing at all.
G151 unless otherwise agreed upon by contractual parties
6.1.2 The xenon arc light and water apparatus must be able
NOTE 5—Air-dry primers, plastic barrier tapes and silicone sealants
to control irradiance at 340 nm, relative humidity, uninsulated have often been found suitable for edge sealing.
blackpaneltemperatureandchambertemperature,andprovide
9.2 Fill all unused specimen positions in the xenon arc light
water spray on the front of the specimens.
and water apparatus’ exposure area with inert specimens (for
example, anodized aluminum panels) to maintain desired
6.2 Mass balance—with a resolution of at least 0.1 g.
airflow.
NOTE 6—Refer to the manufacturer’s instructions for proper operation
7. Reagents and Materials
of the apparatus.
7.1 Sponge. See AnnexA2 for more detailed specifications.
9.3 Program the xenon arc light and water apparatus to run
7.2 Purified Water, as specified in Practice G155 and 8.2.
the exposure cycle shown in Table 1 and in accordance with
manufacturer’sinstructions.Thedurationofthetestintermsof
8. Apparatus Setup
numberofcycles,hours,orradiantdosageshallbeagreedupon
8.1 Maintainandcalibratetheapparatusaccordingtomanu- by contractual parties.
facturer’s instructions.
9.4 Specimens shall be repositioned at a minimum of every
8.2 Water Spray—The water for spray and humidification
twoweeksofoperationtoimproveuniformityofexposure.See
shall be of the same quality listed in Practice G155 and shall Practice G151, Appendix X2 for more specific guidance and
leave no objectionable deposits or stains on the exposed
figures on repositioning of specimens in both rotating rack and
specimens. The water shall have less than 1 mg per litre (1 flat array xenon arc light and water apparatus.
ppm) total dissolved solids and it shall have less than 0.1 mg
9.4.1 Specimens in a rotating rack apparatus shall be repo-
per litre (0.1 ppm) silica. sitioned to the position immediately above it; specimens in the
NOTE 2—Silica levels should be determined using Test Method D4517
top position shall be repositioned to the bottom position.
or equivalent. A combination of deionization and reverse osmosis treat-
9.4.2 Specimens in a flat array apparatus shall be reposi-
mentcaneffectivelyproducewaterwiththedesiredpurity.Incertaincases
tioned to the position immediately to the left; specimens in the
some samples could exude materials into the chamber that can promote
left-most position shall be repositioned to the right-most
deleterious effects on other samples.
position, with front-back and back-front repositioning if appli-
8.3 Qualify the sponges used for the water uptake per the
cable.
procedure in Annex A2. For each xenon arc light and water
apparatus, verify the water uptake capability in accordance
with the procedure in Annex A3 before placing it into service
D7869 − 13
TABLE 1 Exposure Cycle
Black Panel Chamber Air
Irradiance Set
Relative Humidity
A
Step Number Step Minutes Function Temperature Temperature
Point at 340 nm
A
2 Set Point
A A
W/(m ·nm)
Set Point Set Point
1 240 dark + spray — — 40°C 95 %
2 30 light 0.40 50°C 42°C 50 %
3 270 light 0.80 70°C 50°C 50 %
4 30 light 0.40 50°C 42°C 50 %
5 150 dark + spray — — 40°C 95 %
6 30 dark + spray — — 40°C 95 %
7 20 light 0.40 50°C 42°C 50 %
8 120 light 0.80 70°C 50°C 50 %
9 10 dark — — 40°C 50 %
10 Repeat subcycle steps 6 to 9 (shown in bold) an additional 3 times (for a total or 24h=1 cycle).
A
The set point is the target condition for the sensor used at the operational control point and is programmed by the user. When the exposure cycle calls for a particular
set point, the user programs the apparatus to use that exact number. Operational fluctuations are deviations from the indicated set point during equilibrium operation. The
maximum allowable operational fluctuation during equilibrium conditions for the exposure cycle above is ±0.02 W/(m ·nm) for irradiance, ±2.5°C for black panel
temperature, ±2°C for chamber air temperature, and ±10 % for relative humidity.
NOTE 7—Specimen repositioning in 9.4.1 and 9.4.2 is required to
measurements for each position in the xenon arc light and
compensate for variations in light, water, relative humidity and tempera-
water apparatus, in accordance with Annex A3.
ture within the test chamber.
9.5 The test shall be interrupted for repositioning and
11. Keywords
specimen evaluations only during a step without water spray.
11.1 accelerated; automotive; coatings; durability; exposure
10. Report
test; irradiance; lightfastness; weathering; xenon arc
G151. The
10.1 The test report shall conform to Practice
report shall also include the average of three water collection
ANNEXES
A1. DAYLIGHT FILTER IRRADIANCE LIMITS BY WAVELENGTH
(Mandatory Information for Equipment Manufacturers)
A1.1 Conformance to the spectral power distribution in
Total Irradiance Over Indicated
Wavelength Band
Table A1.1 is a design parameter for a xenon-arc source with
Wavelength Band (W/m )
the different optical filters provided. Manufacturers of equip-
(nm) Minimum Maximum
ment claiming conformance to this standard shall be respon- λ < 290 0.00 0.005
290# λ < 295 0.00 0.01
sible for determining conformance to the spectral power
295# λ < 300 0.01 0.04
distributiontableforalllamp/filtercombinationsprovided,and
300# λ < 305 0.10 0.20
305# λ < 310 0.38 0.56
provide information on maintenance procedures to minimize
310# λ < 320 2.29 3.10
any spectral changes that may occur during normal use.
320# λ < 330 4.76 5.82
330# λ < 340 6.84 7.56
340# λ < 350 7.69 9.40
350# λ < 360 8.13 11.00
360# λ < 370 8.32 12.47
370# λ < 380 8.30 13.83
380# λ < 390 8.64 14.40
390# λ < 400 9.23 17.15
2 2
Note: Irradiance in W/m normalized to 0.80 W/(m ·nm) at 340 nm.
D7869 − 13
A2. SPONGE QUALIFICATION PROCEDURE
(Mandatory Information)
A2.1 Cut a section of the homogeneous sponge material to A2.3.2 After a minimum of 1 min., remove the sponge from
a maximum size of 57 mm wide, 127 mm long and 19 mm the water and lightly hold it vertically over the water container
thick. Both sides of the sponge shall have the same water as shown in Fig.A2.2. Continue holding it until the sponge has
absorbance capability. Do not use multi-layer sponges. atmost,onewaterdropper15scomingfromthebottomofthe
sponge.
A2.2 Weigh a damp sponge.
A2.3.3 Turn the sponge horizontally as shown in Fig. A2.3
A2.2.1 Thoroughly saturate the cut sponge with water by
to prevent any more water loss and place it on the tared
soaking it in at least 2 L of water at room temperature (23 6
balance. This will show the additional mass of water absorbed
3°C) for a minimum of 1 min. or until it has reached full
beyond the mass of just the damp sponge. Record the mass.
saturation. Different types of sponges will take different times
A2.3.4 Repeat steps A2.3.1 – A2.3.3 two additional times
to reach full saturation.
and determine an average mass of water held by the sponge for
A2.2.2 Remove as much water as possible from the sponge
the three runs. This will define the saturation capacity of the
through wringing by hand as shown in Fig. A2.1. Weigh it to
sponge (mass of saturated sponge minus mass of damp
the nearest 0.1 g on a calibrated balance capable of at least
sponge).
100.0 g total weight. The preferred type of sponge for this test
method will weigh between 20.0 and 30.
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