Значение и использование

The ability of a paint or coating to resist deterioration of its physical and optical properties caused by exposure to light, heat, and water can be very significant for many applications. This practice is intended to induce property changes associated with end-use conditions, including the effects of sunlight, moisture, and heat. The exposure used in this practice is not intended to simulate the deterioration caused by localized weather phenomena such as atmospheric pollution, biological attack, and saltwater exposure.

CautionsVariation in results may be expected when different operating conditions are used. Therefore, no reference to the use of this practice shall be made unless accompanied by a report prepared according to Section 10 that describes the specific operating conditions used. Refer to Practice G151 for detailed information on the caveats applicable to use of results obtained according to this practice.

Note 3—Additional information on sources of variability and on strategies for addressing variability in the design, execution and data analysis of laboratory accelerated exposure tests is found in Guide G141.

The spectral power distribution of light from fluorescent UV lamps is significantly different from that produced in light and water exposure devices using other light sources. The type and rate of degradation and the performance rankings produced in exposures to fluorescent UV lamps can be much different from those produced by exposures to other types of laboratory light sources.

Interlaboratory comparisons are valid only when all laboratories use the same design of fluorescent UV device, lamp, and exposure conditions.

Reproducibility of test results between laboratories has been shown to be good when the stability of materials is evaluated in terms of performance ranking compared to other materials or to a control. ^, Therefore, exposure of a similar material of known performance (a control) at the same time as the test materials is strongly recommended. It is recommended that at least three replicates of each material be exposed to allow for statistical evaluation of results.

Test results will depend upon the care that is taken to operate the equipment according to Practice G154. Significant factors include regulation of line voltage, temperature of the room in which the device operates, temperature control, and condition and age of the lamps.

All references to exposures in accordance with this practice must include a complete description of the test cycle used.

Область применения

1.1 This practice covers the selection of test conditions for accelerated exposure testing of coatings and related products in fluorescent UV and condensation devices conducted according to Practices G151 and G154. This practice also covers the preparation of test specimens, and the evaluation of test results. Table 1 describes commonly used test conditions.

Note 1—Previous versions of this practice referenced fluorescent UV devices described by Practice , which described very specific equipment designs. Practice has been withdrawn and replaced by Practice G151, which describes performance criteria for all exposure devices that use laboratory light sources, and by Practice G154, which gives requirements for exposing nonmetallic materials in fluorescent UV devices.

Note 2—ISO 11507:1997 also describes fluorescent UV-condensation exposures of paints and coatings.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.3 This standard does not purport to address all of the safety problems 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.

TABLE 1 Test Cycles Commonly Used for Fluorescent UV–Condensation Exposure Testing of Paints and Related Coatings^A

Cycle NumberCycle Description340 nm Irradiance^{B, C}Black Panel Temperature^DTypical Uses^E 18 h UV
4 h condensation
Repeated continuously0.83 W/(m²·nm)
dark period70 ± 2.5 ºC (158 ± 5 ºF)
50 ± 2.5 ºC (122 ± 5 ºF)Automotive coatings^F 24 h UV
4 h condensation
Repeated continuously0.89 W/(m²·nm)
dark period60 ± 2.5 (140 ± 5 ºF)
50 ± 2.5 (122 ± 5 ºF)Industrial maintenance coatings^G 34 h UV
20 h condensation
Repeated continuously0.89 W/(m²·nm)
dark period60 ± 2.5 (140 ± 5 ºF)
50 ± 2.5 (122 ± 5 ºF)Exterior wood coatings 48 h UV
4 h condensation
Repeated continuously0.89 W/(m²·nm)
dark period60 ± 2.5 (140 ± 5 ºF)
50 ± 2.5 (122 ± 5 ºF)General metal coatings

^A The cycles described are not listed in any order indicating importance, and are not necessarily recommended for the applications listed. Additional exposure cycles are described in Practice G154.

^B The irradiance set point given is typical for devices operated without irradiance control. Other irradiance levels may be used, but must be described in the report.

^C Previous editions of Practice D4587 contained non-mandatory irradiance set points in Table 1 that were commonly used in the industry. The previous set points were 0.72 and 0.77 W/(m² · nm) at 340 nm for UVA 340 lamps. The measurement data used to establish these set points was inaccurate, due to an error in calibration on the part of one manufacturer. It has been found that, for most users, the actual irradiance when running at the previous set points was 11 to 15 % higher than the indicated set point. The set points shown in this edition of D4587 do not change the actual irradiances that have been historically used by these users. However, for users of equipment made by another manufacturer, the irradiance control system did not have the measurement inaccuracies described above, so running at the new set points will represent a change in the actual irradiance of the test. If in doubt, users should consult the manufacturer of their device for clarification.

^D Temperature is at equilibrium for either an uninsulated or insulated black panel, although the response of the insulated black panel might be slower than that for the uninsulated black panel. Refer to Practice G151 for more information about the construction and differences between uninsulated and insulated black panels.

^E Typical uses do not imply that results from exposures of these materials according to the cycle described will correlate to those from actual use conditions.

^F SAE J2020 describes the test used in many automotive specifications and requires use of a FS40 fluorescent UVB lamp.

^G Historical convention has established this as a very commonly used test cycle. This cycle may not adequately simulate the effects of outdoor exposure.

^REFERENCE:

ASTM Standards:

D358 Specification for Wood to Be Used as Panels in Weathering Tests of Coatings

D523 Test Method for Specular Gloss

D609 Practice for Preparation of Cold-Rolled Steel Panels for Testing Paint, Varnish, Conversion Coatings, and Related Coating Products

D610 Practice for Evaluating Degree of Rusting on Painted Steel Surfaces

D659 Method of Evaluating Degree of Chalking of Exterior Paints (Withdrawn)

D660 Test Method for Evaluating Degree of Checking of Exterior Paints

D662 Test Method for Evaluating Degree of Erosion of Exterior Paints

D714 Test Method for Evaluating Degree of Blistering of Paints

D772 Test Method for Evaluating Degree of Flaking (Scaling) of Exterior Paints

D823 Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels

D1005 Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers

D1186 Test Methods for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to a Ferrous Base (Withdrawn)

D1400 Test Method for Nondestructive Measurement of Dry Film Thickness of Nonconductive Coatings Applied to a Nonferrous Metal Base (Withdrawn)

D1729 Practice for Visual Appraisal of Colors and Color Differences of Diffusely-Illuminated Opaque Materials

D1730 Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting

D2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates

D2616 Test Method for Evaluation of Visual Color Difference With a Gray Scale

D3359 Test Methods for Measuring Adhesion by Tape Test

D3980 Practice for Interlaboratory Testing of Paint and Related Materials (Withdrawn)

D4214 Test Methods for Evaluating the Degree of Chalking of Exterior Paint Films

D5870 Practice for Calculating Property Retention Index of Plastics

E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

E1347 Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry

G53 Practice for Operating Light- and Water-Exposure Apparatus (Fluorescent UV-Condensation Type) for Exposure of Nonmetallic Materials (Withdrawn)

G113 Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials

G141 Guide for Addressing Variability in Exposure Testing 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

G154 Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials

G169 Guide for Application of Basic Statistical Methods to Weathering Tests

ISO Standard:

ISO 11507:1997 Paints and VarnishesExposure of Coatings to Artificial WeatheringExposure to Fluorescent UV and Water

SAE Standard:

SAE J2020 Accelerated Exposure of Automotive Exterior Materials Using a Fluorescent UV Condensation Apparatus