Measurement
The glossmeter provides a quantifiable way of measuring gloss intensity ensuring consistency of measurement by defining the precise illumination and viewing conditions. The configuration of both illumination source and observation reception angles allows measurement over a small range of the overall reflection angle. The measurement results of a glossmeter are related to the amount of reflected light from a black glass standard with a defined refractive index. The ratio of reflected to incident light for the specimen, compared to the ratio for the gloss standard, is recorded as gloss units.
Measurement angle refers to the angle between the incident and reflected light. Three measurement angles (20°, 60°, and 80°) are specified to cover the majority of industrial coatings applications. The angle is selected based on the anticipated gloss range, as shown in the following table.
| Gloss Range | 60° Value | Notes |
| High Gloss | >70 GU | If measurement exceeds 70 GU, change test setup to 20° |
| Medium Gloss | 10 - 70 GU | |
| Low Gloss | <10 GU | If measurement is less than 10 GU, change test setup to 85° |
For example, if the measurement made at 60° is greater than 70 GU, the measurement angle should be changed to 20° to optimise measurement accuracy.
Two additional angles are used for other materials. An angle of 45° is specified for the measurement of ceramics, films, textiles and anodised aluminium, whilst 75° is specified for paper and printed materials.
Read more about this topic: Glossmeter
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—John Dos Passos (1896–1970)