Standard Practice for Conditioning and Handling of Materials for Natural and Artificial Weathering Tests

Abstract

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.