Scope:

Gloss is the shine or luster on a smooth surface. ASTM C584 is used for establishing specular gloss limits for bright, semi-mat, and mat glazed surfaces. The appearance of gloss is a result of several attributes including specular gloss. Therefore, specular gloss measurements do not always correlate well with visual rankings of glossiness. However, this method is of sufficient accuracy for the intended purpose.

Test Procedure:

In ASTM C584, the surface of the specimens is cleaned with a cotton swab dipped in alcohol. It is dried with a lint-free cloth. The glossmeter is then used to measure the specular gloss of the surface. A glossmeter is an instrument that is used to measure the specular reflection gloss of a surface. Gloss is determined by projecting a beam of light at a fixed intensity and angle onto a surface and measuring the amount of reflected light at an equal but opposite angle. Two readings are taken in the center of each specimen, the second one is taken after rotating the specimen by 90°, and the average of the two readings is calculated. 

Video 01: Method to measure gloss using a glossmeter

Specimen size:

For ASTM C584, the specimens should be 102 by 102 mm in size or larger. Only specimens with a reasonably plane surface should be used because warpage and waviness will affect the result.

Data:

The average specular gloss reading of each specimen is reported.

Conclusion:

ASTM C584 is used for establishing specular gloss limits for bright, semi-mat, and mat glazed surfaces.