Meaning and Purpose
4.1 Specular gloss is mainly used to measure the gloss appearance of films and surfaces. A precise comparison of gloss values is meaningful only if the same measurement procedure and the same general material type are involved. In particular, the gloss values of transparent films should not be compared with those of opaque films and vice versa. Glossiness is a complex property of surfaces that cannot be measured entirely 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.

ASTM D 2457-2021 Standard Test Method for Specular Gloss of Plastic Films and Solid Plastics

Scope of
1.1 The test method describes procedures for measuring the glossiness of opaque and transparent plastic films and solid plastics. It contains four independent gloss angles (Note 1) :

1.1.160 degrees, recommended for medium light films,

1.1.220 degrees, recommended for high light film,

1.1.345 degrees, recommended for medium and low light films,

1.1.485 degrees, recommended for medium and low gloss films, as well

1.1.575 degrees, recommended for plastic siding and soffit.

Note 1: The measuring devices and methods of 85 degrees, 75 degrees, 60 degrees and 20 degrees are repeated with those in test methods D523 and D3679; The equipment and methods for the 45° procedure were also taken from test method C346.

1.2 This standard is not intended to address all safety issues, 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 to determine the applicability of regulatory restrictions prior to use.

ASTM D 2457-2021 Standard Test Method for Specular Gloss of Plastic Films and Solid Plastics

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

1.3 This international Standard has been developed in accordance with the internationally recognized standardization principles established in the Decision on Principles for the Development of International Standards, Guidelines and Recommendations issued by the Committee on Technical Barriers to Trade of the World Trade Organization.