ASTM D6695 is the standard guide for xenon arc exposure of coatings and related coatings. This practice recommends test parameters for daylight exposure testing according to ASTM G151 and G155.

ASTM D6695 Use and factors to consider

As a function of their formulation and application, the coating resists performance degradation caused by exposure to light, heat and water very differently. They also respond very differently to different experimental parameters used to perform UV exposure. ASTM D6695 offers 7 different xenon arc exposure cycles. If the coating is applied, their function will be different:

Cycle 1: General paint

Cycle 2: General paint

Cycle 3: External pigment stains

Cycle 4: Exterior wood stains and removals

Cycle 5: Marine enamel

Cycle 6: Car appearance

Cycle 7: Car interiors

ASTM D6695-2016 Standard Practice for Xenon Arc Exposure to Coatings and Related Coatings

Once the samples are exposed, the mechanical and aesthetic properties of the coatings need to be measured to assess their performance. Depending on your specific application, different parameters will be measured.

Experimental parameter

We need to know which exposure cycle you want to perform on the sample. In addition, we need to know:

The number of 2½ “X5½” samples you wish to test (other sizes can be used, but this needs to be discussed.

Exposure Duration (kilojoules or hours) ASTM D7356M-2013 Standard Test Method for Accelerated Acid Etching Weathering of Automotive varnishes Using xenon Arc Exposure Devices
Meaning and use

5.1 Acid corrosion damage is an important warranty claim item for automobile companies. Therefore, acid etching resistance is an important parameter of automotive exterior wall coatings. The method described in this test method has shown to mimic the acid etch damage of automotive varnish that occurs when these coatings are exposed in Jacksonville, Florida, from May to mid-August. 3,5 The accelerated test described in this standard allows for year-round testing instead of limited outdoor exposure times available for exposure in Jacksonville, Florida.

ASTM D6695-2016 Standard Practice for Xenon Arc Exposure to Coatings and Related Coatings

Step 1: Scope

1.1 This test method includes accelerated exposure tests designed to simulate defects causing acid rain in automotive finish paint 2 occurring at exposure sites in Jacksonville, Florida. Etching defects from external exposure at acid rain test sites in Jacksonville, Florida range from small pit diameters to acid etch spots of 12.7 mm [0.5 in] or larger. The latter type of defect does not occur in other acid etching tests that only produce pits less than 6.35mm [0.25 in] in diameter. 3

Note 1 – Digital images of acid etching defects produced during outdoor acid rain exposure and accelerated tests described in this test method are shown in Appendix X1.

1.2 The accelerated tests described in this test method use xenon arc sources with daylight filters that meet the requirements of Practice G155. Sample spraying with a simulated acid rain solution requires the use of a horizontally flat sample array so that the acid rain solution remains on the sample for a long time.

1.3 There is no known ISO equivalent to this test method.

1.4 Values expressed in SI units or inch-pound units shall be treated separately as standard values. The values stated in each system may not be exactly equivalent; Therefore, each system should be used independently. Combining values from two systems can result in non-compliance.

1.5 This standard is not intended to address all safety concerns (if any) associated with its use. It is the responsibility of users of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory restrictions prior to use. ASTM D7869-2017 Standard Practice for Xenon Arc Exposure Testing for Enhanced Light and Water Exposure for Transport Coatings
ASTM D6695-2016 Standard Practice for Xenon Arc Exposure to Coatings and Related Coatings

Meaning and use
5.1 This test procedure is used to simulate the physical and environmental stresses exposed to coatings for external transportation applications, such as automobiles, in subtropical climates, such as South Florida. It has been found that this subtropical climate leads to particularly severe deterioration of this coating. In addition to high doses of solar radiation, the prolonged water exposure and wet/dry cycles found in southern Florida are particularly important for this deterioration (3). This method was developed to address the shortcomings of historical experiments for transporting coatings, especially automotive coatings (4).

Note 1: This test program was developed through eight years of collaborative testing between automotive and aerospace Oems, material suppliers, and test equipment manufacturers. For published papers on this research, see References.

Step 1: Scope
1.1 This practice specifies operating procedures for controlled irradiance xenon arc lamps and water equipment. The program uses one or more lamps and filters to produce irradiance similar to that of 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 to apply to coatings on other transport vehicles, such as aircraft, trucks and rail vehicles.

ASTM D6695-2016 Standard Practice for Xenon Arc Exposure to Coatings and Related Coatings

1.2 This practice uses a xenon arc source with a specified optical filter. The spectral power distribution (SPD) of lamps and special daylight filters is specified in Annex A1. The irradiance level used in this practice varies between 0.40 and 0.80W/(m 2 ·nm) at 340nm. Water is sprayed on the sample during parts of several dark steps. Water is applied so that the coating will absorb and desorption a large amount of water during the test. In addition, the cycle between wet/dry and warm/cold will cause mechanical stress on the material. These test conditions are designed to simulate physical and chemical stresses in subtropical climates, such as South Florida.

1.3 Values expressed in SI units shall be regarded as standard values. No other units of measurement are included in this standard.

1.4 This standard is not intended to address all safety concerns, if any, associated with its use. It is the responsibility of users of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory restrictions prior to use.