ALTANA Micro-Gloss Manual - Manual (Page 24)

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Measurement techniques
6. Measurement techniques
In accordance with the standard, the reflectometer
value is related to a black glass standard at a
defined index of refraction (generally 1.567) which is
thus equal to 100 units.
Reflectometers are differentiated by the angle of
incidence of the illuminating mechanism.
Geometries are set in the standards at 20°, 60° and
85°.
6.1 Paints and varnishes, plastics and similar materials
The various geometries are distinguished according
to their fields of application as follows:
Semi-gloss surfaces are measured at an angle of
incidence of 60° and should fall within a range from
10 to 70 gloss units.
Highly reflective surfaces with measurement values
exceeding 70 units in the 60° geometry should be
measured at 20°.
On the other hand, matte surfaces with less than 10
gloss units (at 60°) should be measured at the 85°
geometry.
In addition, specific measuring geometries are
defined in some industries, e.g. ceramic and plastic
film applications recommend 45° geometry or paper
and vinyl housing facades use 75° geometry.