ASTM G147-17

4.1 Weathering is an inherently variable science due to the fact that weather itself is variable. In addition, there can be variability in results in artificial accelerated testing even when all devices are running identical exposure cycles. Therefore, it is essential to control all factors as much as possible in order to reduce the overall source of error.

4.2 Proper handling of specimens is extremely important for maintaining the integrity of the material being evaluated. Damage to specimens caused by improper handling and labeling can adversely affect the validity of the testing program, causing loss of money and time. Improper handling can introduce nonstandard procedures into the protocol which may be a significant source of variability, adversely affecting the overall precision of results obtained. Improper handling may also introduce a bias in the results obtained.

4.3 Changes to materials can occur even under a seemingly benign conditioning environment, especially if the specimen has already been exposed. Therefore it is necessary to minimize the number and length of non-testing periods in order that the exposure is the only cause of further changes.

1.1 This practice covers specimen preparation, identification, packing, shipping, handling, and conditioning before, during, and after natural and artificial weathering testing.

1.2 This practice includes details on the conditioning of specimens after exposure and before examination. This practice also covers long-term storage of file specimens.

1.3 Conditioning in this practice does not refer to the specific act of exposing the specimens to the weathering factors.

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.

1.5 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.