1.1 本规范规定了固体和杂色塑料壁板产品的颜色和外观保持性的要求和试验方法。 1.2 保色性测试提供了一种方法，用于估计塑料壁板产品在延长使用期内颜色变化的可接受性。 注1: 已证明，本标准中规定的暴露位置和持续时间可以很好地估计乙烯基和聚丙烯壁板产品在延长使用期内的颜色变化（见 2.2 ). 预计针对外墙典型暴露条件设计的材料也会做出类似反应，但尚未根据经验确定本标准对其他类型塑料墙板的适用性。 1.3 本规范是规范的后续规范 D6864 和 D7251 ，分别涵盖纯色和杂色。本规范结合了两者的涵盖范围，并且与这些标准具有相同的范围。 1.4 规格 D6864 和 D7251 使用Hunter Lab颜色空间测量颜色并评估颜色变化。这些标准要求根据颜色的L、a和b坐标将颜色分为多个区域，并使用具有每个颜色区域唯一系数的椭球值方程来评估颜色变化。 本规范使用CIE 1976 L*a*b*颜色空间测量和评估颜色变化。使用该方法，不需要单独的颜色区域和评估方程。 1.5 本规范中关于样品选择和制备以及风化的规定与规范中的规定相同 D6864 和 D7251 . 1.6 杂色的颜色和外观表征因随机图案中存在多种颜色而变得复杂。本规范中测量杂色的程序基于使用模板参考六个点进行颜色测量。 1.7 本标准规定了一次24个月暴露在三个特定气候区的室外风化，并确定了这些条件下的保色性能要求，以表明在较长的使用期内可接受的性能。然而，只要在任何报告中明确规定了这些条件，本标准中的任何内容都不排除使用不同或额外的气候区，或不同的暴露持续时间。 1.8 单位- 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.9 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 注2: 没有已知的ISO等效于本标准。 1.10 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。

1.1 This specification establishes requirements and test methods for the color and appearance retention of solid and variegated colored plastic siding products. 1.2 Color retention testing provides a method for estimating the acceptability of color change in a plastic siding product over an extended period of service. Note 1: The exposure locations and durations specified in this standard have been shown to provide a good estimation of the color change in vinyl and polypropylene siding products over an extended period of service (see 2.2 ). It is expected that materials designed for the exposure conditions typical of exterior siding will respond similarly, but the applicability of this standard to other types of plastic siding has not been empirically established. 1.3 This specification is a successor to Specifications D6864 and D7251 , which cover solid colors and variegated colors, respectively. This specification combines coverage for both, and has the same scope as those standards. 1.4 Specifications D6864 and D7251 use Hunter Lab color space for measurement of colors and evaluation of color change. These standards require classification of colors into regions based on the L, a, and b coordinates of the color, and evaluation of color changes is done using an ellipsoid value equation having unique coefficients for each color region. This specification uses CIE 1976 L* a* b* color space for measurement and evaluation of color change. Using this method, the need for separate color regions and evaluation equations has been eliminated. 1.5 Provisions for sample selection and preparation, and weathering are the same in this specification as in Specifications D6864 and D7251 . 1.6 Characterization of color and appearance for variegated colors is complicated by the presence of multiple colors in a random pattern. The procedure for measuring variegated colors in this specification is based on using a template to reference six spots for color measurement. 1.7 This standard specifies outdoor weathering in three specific climate zones for a single 24-month exposure, and the color retention performance requirements under these conditions are established to be indicative of acceptable performance over an extended period of service. However, nothing in this standard precludes the use of different or additional climate zones, or different exposure durations, so long as those conditions are clearly specified in any reports. 1.8 Units— The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.9 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. Note 2: There is no known ISO equivalent to this standard. 1.10 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.