Significance and Use
4.1 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.
4.2 Warning—Variation 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.
4.2.1 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.
4.2.2 Interlaboratory comparisons are valid only when all laboratories use the same design of fluorescent UV device, lamp, and exposure conditions.
4.3 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.6,7 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.
4.4 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.
4.5 All references to exposures in accordance with this practice must include a complete description of the test cycle used.
Scope
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 G53, which described very specific equipment designs. Practice G53 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 concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 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.
