ASTM D7869-17

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.

General Information

• Status: Published
• Publication Date: 31-Jan-2017
• ICS: 17.040.20 - Properties of surfaces
• ICS: 25.220.99 - Other treatments and coatings
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.27 - Accelerated Testing

Relations

• Replaces: ASTM D7869-13 - Standard Practice for Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings
• Effective Date: 01-Feb-2017
• Refers: ASTM G147-17 - Standard Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests
• Effective Date: 01-Jun-2017
• Refers: ASTM G113-14 - Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
• Effective Date: 01-Mar-2014
• Refers: ASTM G151-10 - Standard Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
• Effective Date: 01-Apr-2010
• Refers: ASTM D4517-04(2009) - Standard Test Method for Low-Level Total Silica in High-Purity Water by Flameless Atomic Absorption Spectroscopy
• Effective Date: 01-Oct-2009
• Refers: ASTM G151-09 - Standard Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
• Effective Date: 01-Jul-2009
• Refers: ASTM G113-09 - Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
• Effective Date: 15-Jun-2009
• Refers: ASTM G147-09 - Standard Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests
• Effective Date: 01-Feb-2009
• Refers: ASTM G113-08 - Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
• Effective Date: 01-Aug-2008
• Refers: ASTM G113-06 - Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
• Effective Date: 01-Dec-2006
• Refers: ASTM G113-06e1 - Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
• Effective Date: 01-Dec-2006
• Refers: ASTM G151-06 - Standard Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
• Effective Date: 15-Nov-2006
• Refers: ASTM G155-05a - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 01-Oct-2005
• Refers: ASTM G113-05 - Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
• Effective Date: 15-Aug-2005
• Refers: ASTM G155-05 - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 01-Jul-2005

Overview

ASTM D7869-17: Standard Practice for Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings establishes a methodology for simulating environmental stresses that exterior coatings on transportation vehicles, such as automobiles, trucks, railcars, and aircraft, may experience in subtropical climates. This standard is particularly relevant for environments like southern Florida, known for intense solar radiation and prolonged wet/dry cycles. By employing a controlled irradiance xenon arc light and water apparatus, ASTM D7869-17 enables manufacturers and researchers to replicate the critical factors contributing to coating deterioration, such as UV exposure, water uptake, thermal cycling, and mechanical stress.

Key Topics

• Accelerated Weathering: Utilizes a xenon arc light source with specific optical filters to mimic the spectrum of natural sunlight, focusing particularly on UV and visible light ranges.
• Water Exposure Cycling: Recreates natural moisture absorption and release in coatings through controlled spraying and humidity cycles, reflective of typical outdoor conditions.
• Irradiance Control: Ensures the intensity of light at 340 nm is maintained within prescribed limits to avoid non-representative chemical changes.
• Thermal and Mechanical Stress: The protocol cycles between wet/dry and warm/cool conditions to accelerate degradation phenomena, simulating daily and seasonal fluctuations.
• Comprehensive Test Apparatus: Specifies detailed requirements for apparatus calibration, water purity, and specimen handling, ensuring reproducibility and reliability.

Applications

This standard practice is crucial for:

• Automotive OEMs and Suppliers: Evaluating the durability and longevity of exterior coatings on cars, trucks, and specialty vehicles when subjected to harsh climates.
• Aerospace Coating Assessment: Testing coatings on aircraft that must remain resilient under both intense sunlight and repeated moisture cycles.
• Rail and Commercial Vehicle Industries: Simulating weathering effects on vehicles exposed to outdoor storage and operation over extended periods.
• Coating Formulators: Improving and qualifying new materials or technologies intended for exterior use, thus accelerating product development cycles.
• Quality Assurance & Regulatory Compliance: Enabling organizations to benchmark their products against internationally recognized standards for accelerated weathering and exposure.

Related Standards

ASTM D7869-17 references several other key ASTM standards relevant to artificial weathering and materials testing:

• ASTM G151: Practice for exposing nonmetallic materials in accelerated test devices that use laboratory light sources.
• ASTM G155: Practice for operating xenon arc light apparatus for exposure of non-metallic materials.
• ASTM G113: Terminology relating to natural and artificial weathering tests of nonmetallic materials.
• ASTM G147: Practice for conditioning and handling of nonmetallic materials for weathering tests.
• ASTM D4517: Test method for low-level total silica in high-purity water by flameless atomic absorption spectroscopy.

Practical Value

Implementing ASTM D7869-17 helps ensure that transportation coatings are resilient against real-world weathering challenges, supporting product durability, customer satisfaction, and reduced maintenance costs. By closely replicating the harshest environmental conditions, this standard allows manufacturers to identify potential failure modes such as gloss loss, color change, adhesion issues, blistering, and cracking before products reach the market. Adhering to ASTM D7869-17 equips organizations with a robust testing regime that aligns with industry best practices for accelerated durability testing, a crucial aspect for global competitiveness in the coatings industry.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7869 − 17
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
2.1 ASTM Standards:
1.1 This practice specifies the operating procedures for a
controlled irradiance xenon arc light and water apparatus. The D4517 Test Method for Low-Level Total Silica in High-
Purity Water by Flameless Atomic Absorption Spectros-
procedure uses one or more lamp(s) and optical filter(s) to
produce irradiance similar to sunlight in the UV and visible copy
G113 Terminology Relating to Natural andArtificial Weath-
range. It also simulates the water absorption and stress cycles
experienced by automotive exterior coatings under natural ering Tests of Nonmetallic Materials
G147 Practice for Conditioning and Handling of Nonmetal-
weathering conditions. This practice has also been found
applicable to coatings on other transportation vehicles, such as lic Materials for Natural and Artificial Weathering Tests
G151 Practice for Exposing Nonmetallic Materials inAccel-
aircraft, trucks and rail cars.
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
substantial amounts of water during testing. In addition, the 3.2 transportation coatings, n—exterior coatings used for
cycling between wet/dry and warm/cool will induce mechani-
vehicles subjected to natural weathering conditions such as
cal stresses into the materials. These test conditions are automobiles, aircraft, trucks, rail cars, etc.
designed to simulate the physical and chemical stresses from
4. Summary of Practice
environments in a subtropical climate, such as southern
Florida.
4.1 Test specimens are exposed to specific test conditions
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
1 2
This practice is under the jurisdiction of ASTM Committee D01 on Paint and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Related Coatings, Materials, and Applications and is the direct responsibility of contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Subcommittee D01.27 on Accelerated Testing. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Feb. 1, 2017. Published March 2017. Originally the ASTM website.
approved in 2013. Last previous edition approved in 2013 as D7869 – 13.DOI: The boldface numbers in parentheses refer to the list of references at the end of
10.1520/D7869-17. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7869 − 17
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 − 17
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
(Mandatory Information for Equipment Manufacturers)
A1. DAYLIGHT FILTER IRRADIANCE LIMITS BY WAVELENGTH
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 − 17
(Mandatory Information)
A2. SPONGE QUALIFICATION PROCEDURE
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. at most, one water drop per 15 seconds coming from the
bottom of the 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 Wring sponge tightly by hand as shown in Fig.A2.1
the three runs. This will define the saturation capacity of the
until no water drips are observed over a period of 15 seconds.
sponge (mass of saturated sponge minus mass of damp
Weigh it to the nearest 0.1 g on a calibrated balance capable of
sponge).
at least 100.0 g total weight. The preferred type of sponge for
this test method will weigh between 20.0 and 30.0 g after A2.4 Acceptance criteria for the saturation capacity of the
removing excess water. sponge is as follows:
Minimum: 40.0 grams
A2.2.3 Tare the balance to zero and remove the damp
Preferred: 50.0 grams
sponge from the balance. Subsequent weighing of the sponge
Maximum: no maximum
will thus record only the additional water absorbed into the
sponge.
A2.5 If the criterion in Step 4 (A2.4) is not met, a new
source of sponge material must be obtained for testing.
A2.3 Weigh a saturated sponge.
A2.3.1 Saturatethespongeagaininaminimum2Lofroom
temperature water by keeping the sponge totally immersed for
a minimum of 1 min.
FIG. A2.1 Removing Water from Sponge through Wringing by
Hand FIG. A2.2 Holding Sponge Vertically
D7869 − 17
FIG. A2.3 Holding Sponge Horizontally
(Mandatory Information)
A3. XENON ARC LIGHT AND WATER APPARATUS WATER SPRAY SYSTEM QUALIFICATION PROCEDURE
A3.1 Confirm spray nozzles are operational and spray A3.6 Sponges shall be in the same orientation as a test
system is programmed per the manufacturer’s instructions. specimen when mounted in the xenon light and water appara-
tus. Mount the sponges as follows:
Follow the apparatus manufacturer’s requirements for mini-
mumwaterpressureforcorrectoperationofthexenonarclight
A3.6.1 One in each tier of the rotating rack xenon arc light
and water apparatus. Clean, repair and adjust water flow or
and water apparatus (for example, upper, middle, and lower
pressure as needed. In order to prevent artificially high sponge
positions). Start the sponges directly opposite from the spray
absorption values, the apparatus (and any sponge specimen
nozzles (that is, on the other side of the rack, away from the
holders which may be used) shall be designed to only allow
nozzles).
water absorption from the front, lamp-facing side of the
A3.6.2 One in each of three areas on the tray of a flat array
sponge. Water spray and water run-off from other specimen
xenon arc light and water apparatus (that is, the top-left,
areas shall be prevented from reaching the sponge top, sides,
middle-middle, and bottom-right positions).
and back. See Appendix X3 for examples of sponge specimen
holderdesignsthatfulfilltherequirementsofthissectionA3.1.
A3.7 Set and run the following cycle in xenon arc light and
water apparatus as per manufacturer’s instructions: 5 min. dark
A3.2 Prepare sponges in accordance with AnnexA2, Step 1
+ spray at 50°C chamber air temperature, front spray only.
(A2.1).
A3.8 Weighing sponges again:
A3.3 Wet the sponges thoroughly with water with a purity
A3.8.1 If specimen holders are used, remove specimen
as specified in 8.2. Do not use tap water. Water should be
holders from the xenon arc light and water apparatus.Wipe the
dripping from sponges.
specimen holders dry and weigh and record mass for each
A3.4 Wring sponge tightly by hand as shown in Fig. A2.1
specimen holder (including the sponge) to the nearest 0.1 g.
until no water drips are observed over a period of 15 seconds.
A3.8.2 Ifnospecimenholdersareused,removethesponges
This will result in a damp sponge.
from the xenon arc light and water apparatus and weigh and
record mass for each sponge to the nearest 0.1 g.
A3.5 Weighing sponges:
A3.5.1 If specimen holders are used, place damp sponges in A3.9 Calculate the amount of water uptake, to the nearest
specimen holders with each sponge mounted within a single 0.1 g. Water uptak
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7869 − 13 D7869 − 17
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
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/(m ·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.
2. Referenced Documents
2.1 ASTM Standards:
D4517 Test Method for Low-Level Total Silica in High-Purity Water by Flameless Atomic Absorption Spectroscopy
G113 Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
G147 Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests
G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
G155 Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
3. Terminology
3.1 Definitions applicable to this standard can be found in Terminology G113.
3.2 transportation coatings, n—exterior coatings used for vehicles subjected to natural weathering conditions such as
automobiles, aircraft, trucks, rail cars, etc.
4. Summary of Practice
4.1 Test specimens are exposed to specific test conditions designed to simulate the physical and chemical stresses from
environments in a subtropical climate, such as southern Florida. The test conditions consist of a primary test cycle and a sub-cycle.
The primary test cycle includes two long water exposures and a single, long light exposure with precise spectral match to daylight
as described in Annex A1. It is designed to reproduce water penetration failures, such as adhesion, blistering and diffusion of small
This practice is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.27 on Accelerated Testing.
Current edition approved June 1, 2013Feb. 1, 2017. Published June 2013March 2017. DOI: 10.1520/D7869-13.Originally approved in 2013. Last previous edition approved
in 2013 as D7869 – 13.DOI: 10.1520/D7869-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
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molecules (1). The sub-cycle consisting of shorter alternating water and light exposures is designed to simulate cyclic stresses
such as cracking and surface erosion. These two cycles are designed to replicate the common types of failures driven by the
interaction of photo-oxidation during daylight and hydrolysis during water exposure that are seen in a subtropical climate such as
gloss loss, color change, adhesion, blistering and cracking (2).
5. 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.
6. Apparatus
6.1 The xenon arc light and water apparatus shall comply with Practice G155.
6.1.1 The xenon arc light and water apparatus shall have an uninsulated black panel thermometer as described in Practice G151
unless otherwise agreed upon by contractual parties
6.1.2 The xenon arc light and water apparatus must be able to control irradiance at 340 nm, relative humidity, uninsulated black
panel temperature and chamber temperature, and provide water spray on the front of the specimens.
6.2 Mass balance—with a resolution of at least 0.1 g.
7. Reagents and Materials
7.1 Sponge. See Annex A2 for more detailed specifications.
7.2 Purified Water, as specified in Practice G155 and 8.2.
8. Apparatus Setup
8.1 Maintain and calibrate the apparatus according to manufacturer’s instructions.
8.2 Water Spray—The water for spray and humidification shall be of the same quality listed in Practice G155 and shall leave
no objectionable deposits or stains on the exposed specimens. The water shall have less than 1 mg per litre (1 ppm) total dissolved
solids and it shall have less than 0.1 mg per litre (0.1 ppm) silica.
NOTE 2—Silica levels should be determined using Test Method D4517 or equivalent. A combination of deionization and reverse osmosis treatment can
effectively produce water with the desired purity. In certain cases some samples could exude materials into the chamber that can promote deleterious
effects on other samples.
8.3 Qualify the sponges used for the water uptake per the 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 and at least once
per year thereafter. Follow the recommendations of the manufacturer of the xenon arc light and water apparatus for additional
checks, if any.
8.4 Fit the xenon arc light and water apparatus with a special daylight filter(s) in accordance with the requirements of Annex
A1.
NOTE 3—Contact the xenon arc light and water apparatus manufacturer for the proper optical filter(s) required. Follow the manufacturer’s
recommendations for optical filter maintenance.
8.5 Other optical filters may be used by mutual agreement between the contractual parties.
NOTE 4—Minor differences in the resultant spectral power distribution (especially in the short wavelength UV region) can have an impact on the test
results. Follow the manufacturer’s recommendations for xenon arc lamp and optical filter maintenance (5).
9. Test Procedure
9.1 Refer to Practice G147 for specimen preparation, conditioning and handling. All test specimens must be clean and free from
fingerprints or other surface contaminants before testing. Prepare a specimen for exposure to fit the specimen mounting fixture
being used, if any. Follow the manufacturers’ guidelines for specimen size and mounting.
9.1.1 Seal any cut edges on the test specimens if required, as agreed between contractual parties. For example, (a) rust and
corrosion products from the cut edges of metal panels may stain the test specimens, (b) by-products from the cut edges of plastic
substrates may leach out and contaminate test specimens, and (c) other panels may not require any edge sealing at all.
NOTE 5—Air-dry primers, plastic barrier tapes and silicone sealants have often been found suitable for edge sealing.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
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9.2 Fill all unused specimen positions in the xenon arc light and water apparatus’ exposure area with inert specimens (for
example, anodized aluminum panels) to maintain desired airflow.
NOTE 6—Refer to the manufacturer’s instructions for proper operation of the apparatus.
9.3 Program the xenon arc light and water apparatus to run the exposure cycle shown in Table 1 and in accordance with
manufacturer’s instructions. The duration of the test in terms of number of cycles, hours, or radiant dosage shall be agreed upon
by contractual parties.
9.4 Specimens shall be repositioned at a minimum of every two weeks of operation to improve uniformity of exposure. See
Practice G151, Appendix X2 for more specific guidance and figures on repositioning of specimens in both rotating rack and flat
array xenon arc light and water apparatus.
9.4.1 Specimens in a rotating rack apparatus shall be repositioned to the position immediately above it; specimens in the top
position shall be repositioned to the bottom position.
9.4.2 Specimens in a flat array apparatus shall be repositioned to the position immediately to the left; specimens in the left-most
position shall be repositioned to the right-most position, with front-back and back-front repositioning if applicable.
TABLE 1 Exposure Cycle
Black Panel Chamber Air
Irradiance Set
Relative Humidity
A
Step Number Step Minutes Function Point at 340 nm Temperature Temperature
A
Set Point
2 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 24 h = 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.
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NOTE 7—Specimen repositioning in 9.4.1 and 9.4.2 is required to compensate for variations in light, water, relative humidity and temperature within
the test chamber.
9.5 The test shall be interrupted for repositioning and specimen evaluations only during a step without water spray.
10. Report
10.1 The test report shall conform to Practice G151. The report shall also include the average of three water collection
measurements for each position in the xenon arc light and water apparatus, in accordance with Annex A3.
11. Keywords
11.1 accelerated; automotive; coatings; durability; exposure test; irradiance; lightfastness; weathering; xenon arc
ANNEXES
(Mandatory Information for Equipment Manufacturers)
A1. DAYLIGHT FILTER IRRADIANCE LIMITS BY WAVELENGTH
(Mandatory Information for Equipment Manufacturers)
A1.1 Conformance to the spectral power distribution in Table A1.1 is a design parameter for a xenon-arc source with the different
Total Irradiance Over Indicated
Wavelength Band
Wavelength Band (W/m )
(nm) Minimum Maximum
λ < 290 0.00 0.005
290 # λ < 295 0.00 0.01
295 # λ < 300 0.01 0.04
300 # λ < 305 0.10 0.20
305 # λ < 310 0.38 0.56
310 # λ < 320 2.29 3.10
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.
optical filters provided. Manufacturers of equipment claiming conformance to this standard shall be responsible for determining
conformance to the spectral power distribution table for all lamp/filter combinations provided, and provide information on
maintenance procedures to minimize any spectral changes that may occur during normal use.
(Mandatory Information)
A2. SPONGE QUALIFICATION PROCEDURE
(Mandatory Information)
A2.1 Cut a section of the homogeneous sponge material to a maximum size of 57 mm wide, 127 mm long and 19 mm thick. Both
sides of the sponge shall have the same water absorbance capability. Do not use multi-layer sponges.
A2.2 Weigh a damp sponge.
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A2.2.1 Thoroughly saturate the cut sponge with water by soaking it in at least 2 L of water at room temperature (23 6 3°C) for
a minimum of 1 min. or until it has reached full saturation. Different types of sponges will take different times to reach full
saturation.
A2.2.2 Remove as much water as possible from the sponge through wringing Wring sponge tightly by hand as shown in Fig. A2.1.
until no water drips are observed over a period of 15 seconds. Weigh it to the nearest 0.1 g on a calibrated balance capable of at
least 100.0 g total weight. The preferred type of sponge for this test method will weigh between 20.0 and 30.0 g after removing
excess water.
A2.2.3 Tare the balance to zero and remove the damp sponge from the balance. Subsequent weighing of the sponge will thus
record only the additional water absorbed into the sponge.
A2.3 Weigh a saturated sponge.
A2.3.1 Saturate the sponge again in a minimum 2 L of room temperature water by keeping the sponge totally immersed for a
minimum of 1 min.
A2.3.2 After a minimum of 1 min., remove the sponge from the water and lightly hold it vertically over the water container as
shown in Fig. A2.2. Continue holding it until the sponge has at most, one water drop per 15 sseconds coming from the bottom
of the sponge.
A2.3.3 Turn the sponge horizontally as shown in Fig. A2.3 to prevent any more water loss and place it on the tared balance. This
will show the additional mass of water absorbed beyond the mass of just the damp sponge. Record the mass.
A2.3.4 Repeat steps A2.3.1 – A2.3.3 two additional times and determine an average mass of water held by the sponge for the three
runs. This will define the saturation capacity of the sponge (mass of saturated sponge minus mass of damp sponge).
A2.4 Acceptance criteria for the saturation capacity of the sponge is as follows:
Minimum: 40.0 grams
Preferred: 50.0 grams
Maximum: no maximum
A2.5 If the criterion in Step 4 (A2.4) is not met, a new source of sponge material must be obtained for testing.
FIG. A2.1 Removing Water from Sponge through Wringing by Hand
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FIG. A2.2 Holding Sponge Vertically
FIG. A2.3 Holding Sponge Horizontally
(Mandatory Information)
A3. XENON ARC LIGHT AND WATER APPARATUS WATER SPRAY SYSTEM QUALIFICATION PROCEDURE
(Mandatory Information)
A3.1 Confirm spray nozzles are operational and spray system is programmed per the manufacturer’s instructions. Follow the
apparatus manufacturer’s requirements for minimum water pressure for correct operation of the xenon arc light and water
apparatus. Clean, repair and adjust water flow or pressure as needed. In order to prevent artificially high sponge absorption values,
the apparatus (and any sponge specimen holders which may be used) shall be designed to only allow water absorption from the
front, lamp-facing side of the sponge. Water spray and water run-off from other specimen areas shall be prevented from reaching
the sponge top, sides, and back. See Appendix X3 for examples of sponge specimen holder designs that fulfill the requirements
of this section A3.1.
A3.2 Prepare sponges in accordance with Annex A2, Step 1 (A2.1).
A3.3 Wet the sponges thoroughly with water with a purity as specified in 8.2. Do not use tap water. Water should be dripping from
sponges.
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A3.4 Remove as much Wring sponge tightly by hand as shown in Fig. A2.1water as possible from the sponge through wringing
by hand. until no water drips are observed over a period of 15 seconds. This will result in a damp sponge.
A3.5 Weighing sponges:
A3.5.1 If specimen holders are used, place damp sponges in specimen holders with each sponge mounted within a single exposure
window. Wipe the specimen holders dry and weigh and record mass for each specimen holder (including the sponge) to the nearest
0.1 g.
A3.5.2 If no specimen holders are used, weigh and record mass for each sponge to the nearest 0.1 g.
A3.6 Sponges shall be in the same orientation as a test specimen when mounted in the xenon light and water apparatus. Mount
the sponges as follows:
A3.6.1 One in each tier of the rotating rack xenon arc light and water apparatus (for example, upper, middle, and lower positions).
Start the sponges directly opposite from the spray nozzles (that is, on the other side of the rack, away from the nozzles).
A3.6.2 One in each of three areas on the tray of a flat array xenon arc light and water apparatus (that is, the top-left, middle-middle,
and bottom-right positions).
A3.7 Set and run the following cycle in xenon arc light and water apparatus as per manufacturer’s instructions: 5 min. dark + spray
at 50°C chamber air temperature, front spray only.
A3.8 Weighing sponges again:
A3.8.1 If specimen holders are used, remove specimen holders from the xenon arc light and wat
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