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Universal Measurement Angle- 60º
All gloss levels can be measured using the standard measurement angle of 60º. This is used as the reference angle with the complimentary angles of 85º and 20º often used for low and high gloss levels respectively.
Low Gloss- 85º
For improved resolution of low gloss a grazing angle of 85º is used to measure the surface. This angle is recommended for surfaces which measure less than 10 GU when measured at 60º.
This angle also has a larger measurement spot which will average out differences in the gloss of textured or slightly uneven surfaces.
High Gloss- 20º
The acute measurement angle of 20º gives improved resolution for high gloss surfaces. Surfaces that measure 70 GU and above at the standard angle of 60º are often measured with this geometry.
The 20º angle is more sensitive to haze effects that affect the appearance of a surface.
Gloss paints have a highly reflective smooth surface. When measured with a 60° glossmeter, typical readings are >70 GU
Semi-gloss paints have a glossy appearance but are not as reflective as gloss paints. When measured with a 60° glossmeter, typical readings are 30-45 GU
Satin paints have a mid-sheen finish. When measured with a 60° glossmeter, typical readings are 20-30 GU
Low sheen paints have a lower levels of gloss /sheen. When measured with a 60° glossmeter, typical readings are 5-19 GU
Flat paints diffuse light and therefore have a very matt finish. When measured with a 60° glossmeter, typical readings are <5 GU
All standard gloss meters are designed for flat surfaces, if they are used on a curved surface, the measurement beam is reflected away from the instrument detector resulting incorrect readings. The more curved the surface the greater the error.
The solution to this problem is to using a very small area. The light is slightly scattered by the curved surface, however as long as the reflected beam remains sufficiently narrow to remain within the instrument detector the reading will be correct. The Novo-Curve gloss meter has been designed for this purpose and is specified for measuring cylinders and spheres with very low diameters. The Novo-Curve was developed in conjunction with the National Physics Laboratory (NPL).
The Novo-Curve gloss-meter has a very small measurement spot (2mm) that can be used to measure the gloss of very small parts or resolve differences in gloss across small areas.
To get equivalent readings to a standard gloss-meter on surfaces that are slightly irregular it is recommended that the average value is taken of several readings.
These instruments have been used to resolve the gloss differences across holograms, measure the polish on coins, steering wheels and extruded pipe work.
When irregular or textured surfaces are measured, the small measurement area can give different gloss values compared to a standard meter that has larger measurement area. To produce comparable results, take 10 measurements on the Novo-Curve gloss meter and use the statistic function to calculate the average reading.