Gloss meters are used in all manufacturing processes.
The gloss measurement below 60 ° has established itself for the paint industry, the plastics industry and the metal industry. For matt and high gloss, there are extra measuring angles of 20 ° and 85 °. Also multi-angle devices (up to 3 measuring angles) and a combination with coating thickness gauge are on the market. The graphic industry uses according to DIN 54502 their own standards with 45 ° and 75 °.
Gloss is a surface property characterized by the fact that incident light is reflected in one direction. The less scattering is present, which means as little light is reflected in different other directions, the higher the gloss.
- High reflection in one direction
- Hardly scattering in other directions
- Metal mirror: all incident radiation is reflected at an angle
- High scattering of the reflected light
- Low proportion of light in the direction of the reflection angle
- Ideal Matt: evenly distributed in all spatial directions
In the gloss measurement with a reflectometer (gloss meter), a light beam is guided at a certain angle to the surface to be measured. Then the amount of light is measured, which is radiated again at the angle of reflection. The measured value is usually reproduced as a gloss unit, which is based on the standard set in DIN EN ISO 2813: a black polished glass plate with GE = 100.
For metallic mirror surfaces, vapor-deposited and polished aluminum mirrors are also used for calibration, since gloss values of up to 2000 are possible here. In order to create uniform conditions for the gloss measurement in the industry, reflectometers and their handling were internationally standardized.
The reflectometer value is significantly influenced by the angle of incidence used. In order to be able to clearly distinguish surfaces from high gloss to dull matt, 3 angles of incidence (geometries) were standardized:High gloss surfaces in 20 ° geometry, medium gloss in 60 ° geometry and matt in 85 ° geometry.
- 20 ° applies when more than 70 GU is detected below 60 °
- 60 ° is used when determining below 60 ° between 10 and 70 GU
- 85 ° is used in less than 10 GU
These 3 geometries are used in many industrial sectors such as paints, plastics and metals.
The graphics industry also uses devices with 45 ° geometry according to DIN 54502 and 75 ° geometry according to Tappi T 480. Typical applications are: ceramics, foils, vinyl, cardboard, paper and other substrates.
For the standardized determination of the gloss level, gloss measuring instruments from different manufacturers with different measuring openings are offered. There are also devices that combine gloss measurement with other options, such as coating thickness measurement. For the selection of a gloss meter, the exact application and size of the parts to be measured should be determined before the purchase.
Further information can be found on our Knowledge page Gloss measurement.