4.1 Specular gloss is used primarily as a measure of the shiny appearance of films and surfaces. Precise comparisons of gloss values are meaningful only when they refer to the same measurement procedure and same general type of material. In particular, gloss values for transparent films should not be compared with those for opaque films, and vice versa. Gloss is a complex attribute of a surface which cannot be completely measured by any single number.

4.2 Specular gloss usually varies with surface smoothness and flatness. It is sometimes used for comparative measurements of these surface properties.

1. Scope

1.1 This test method describes procedures for the measurement of gloss of plastic films and solid plastics, both opaque and transparent. It contains four separate gloss angles (Note 1):

1.1.1 60-deg, recommended for intermediate-gloss films,

1.1.2 20-deg, recommended for high-gloss films,

1.1.3 45-deg, recommended for intermediate and low-gloss films,

1.1.4 85-deg, recommended for intermediate and low gloss films, and

1.1.5 75-deg, recommended for plastic siding and soffit.

Note 1—The 85-deg, 75-deg, 60-deg, and 20-deg apparatus and method of measurement duplicate those in Test Method D523 and D3679; those for the 45° procedure are similarly taken from Test Method C346.

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 and health practices and determine the applicability of regulatory limitations prior to use.

Note 2—There is no known ISO equivalent to this standard.

Test Item 测试名称: ASTM D2457 Specular gloss 镜面光泽度

Test Requirement 测试要求：

测试角度为20°、60°、85°

Sample Size 样品数量 / 送样规格: 最小尺寸: 80mm×20mm, 5 pcs
Lead Time / TAT (Turn Around Time) 测试周期: 常规服务 Regular service 7-9 working days

Report Summary 报告摘要: