【国外标准】 Standard Practice for Selection of Coating Specimens for Appearance Measurements

4.1 Many of the specimens that are regularly submitted to measurement depart in some degree from the ideal requirements. For this reason instrumental readings are affected importantly by the manner in which specimens are selected and presented for measurement. Reproducible measurements are facilitated by standardization and control of test conditions.1.1 This practice provides a guide to selection of specimens for appearance measurement by reflected light as well as a discussion of factors to be considered in their preparation for measurement. Standardized selection and presentation procedures will assist in achieving agreement between evaluations carried out in different laboratories as well as helping to achieve better correlations between visual evaluations and instrumental measurements.NOTE 1: This standard is not a practice for preparation of test panels of coatings; see Practices D823.1.2 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.1.3 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.