4.1 Weathering is an inherently variable science because weather itself is variable. In addition, even if all devices run the same exposure cycle, results from manually accelerated tests may vary. Therefore, all factors need to be controlled as much as possible to reduce the overall source of error.

4.2 Proper handling of samples is important to maintain the integrity of the material being evaluated. Damage to specimens due to improper handling and labeling can adversely affect the effectiveness of test procedures, resulting in loss of money and time. Improper handling can introduce non-standard procedures into the scheme, which can be a significant source of variability, adversely affecting the overall accuracy of the results obtained. Improper processing may also introduce bias in the obtained results.

4.3 The material will change even under seemingly benign conditioning conditions, especially if the sample has been exposed. Therefore, it is necessary to minimize the number and length of non-test periods so that exposure is a cause for further changes.

ASTM G147-2017 Standard Practice for Condition Regulation and Handling of Non-Metallic Materials for Natural and Artificial Climatic Testing

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1.1 This practice covers sample preparation, identification, packaging, transportation, handling and conditioning before, during and after natural and artificial aging tests.

1.2 This practice includes detailed information on the conditioning of specimens after exposure and before examination. This practice also includes long-term storage of sample files.

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

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.

ASTM G147-2017 Standard Practice for Condition Regulation and Handling of Non-Metallic Materials for Natural and Artificial Climatic Testing

Note 1: There is no equivalent ISO standard describing procedures for the identification, transport, conditioning and handling of specimens used for natural or artificial ageing tests. ISO 139 and ISO 291 describe procedures for adjusting specimens before and during physical performance tests.

1.5 This international standard is based on internationally recognized standardization principles established in the Decision on Principles for the Development of International Standards, Guidelines and Recommendations issued by the WTO Committee on Technical Barriers to Trade.