An instrument has been used to resolve the gloss differences across holograms measure the polish on coins, steering wheels and extruded pipework.
The Novo-Curve Gloss Meter has a very small measurement spot of 2mm that is 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 from several readings.
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.
How can I measure the gloss of curved surfaces?
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 in incorrect readings. The more curved the surface the greater the error.
The solution to this problem is to use 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 Gloss Meter was developed in conjunction with the National Physics Laboratory (NPL).
It has been seen that standard tiles kept in optimum conditions can become contaminated and change up to 2 GU in three years.
Standard tiles used in "working" conditions will require regular calibration or checking.
A period of one year between tile re-calibration should be regarded as a minimum period. If a calibration standard becomes permanently scratched or damaged at any time it will require immediate recalibration or replacement.
The international standards state that it is the tile that is calibrated and traceable not the gloss-meter, however, it is recommended that the instrument is also sent to an accredited service center to verify its operation on an annual or bi-annual basis dependent on the operating conditions
Gloss meters are very stable and will need infrequent calibration. To judge when a calibration is necessary simply place the gloss meter on its calibration tile and take a test reading. If the reading is less than 0.2 GU from the assigned calibration value for the tile re-calibration is not necessary.
The ratio of light
reflected at a specified angle to that incident
on the surface at the same angle on the
other side of the
|G ∝ S
Contrast Gloss (also called
Lustre & Haze)
|Gloss at grazing
angles of incidence
|G ∝ S
|Ratio of specularly reflected light and that diffusely reflected
normal to the surface
|G ∝ D
|A measurement of the absence of haze or a milky appearance adjacent to the specularly reflected
|G ∝ B - D
|G ∝ dR
Absence of surface texture gloss
|Perception of surface smoothness and uniformity||Overall visual assessment|