ASTM International Standard Specification for Color and Appearance Retention of Variegated Color Plastic Siding Products ASTM D7251-09

This specification establishes requirements and test methods for the color and appearance retention of variegated color plastic siding products. Color retention testing provides a method for estimating the acceptability of color change in a siding product over a period of years of service. Characterization of color and appearance for variegated colors is complicated by the presence of multiple colors in a random pattern. The procedure is based on using a template to reference 6 spots for color measurement. The color region for a color is determined by measuring the Hunter L, a, b color values for a sample population and calculating the average Hunter L, a, b color value. Ellipsoid Value Equations are used to determine the ellipsoid value representing the change in color due to weathering. Samples shall be exposed at three test sites: Temperate Northern represented by a site located in Louisville, KY or Cleveland, OH; hot, humid represented by a site located in Miami, FL, and hot, dry represented by a site located in Phoenix, Arizona. Materials shall be tested and the individual grades shall conform to specified values of ellipsoid value, color retention, and variegation change.