Color Knowledge

  • how gloss is measured?

  • A glossmeter (also gloss meter) is an instrument which is used to measure the specular reflection (gloss) of a surface. Gloss is determined by projecting a beam of light at a fixed intensity and angle onto a surface and measuring the amount of reflected light at an equal but opposite angle.
    There are a number of different geometries available for gloss measurement each being dependant on the type of surface to be measured. For non-metals such as coatings and plastics the amount of reflected light increases with an increase in the angle of illumination as some of the light penetrates the surface material and is absorbed into it or diffusely scattered from it depending on its colour. Metals have a much higher reflection and are therefore less angularly dependant.

      

    Measurement / Angle Selection
    Measurement angle refers to the angle between the incident and reflected light. Three measurement angles (20°, 60°, and 85°) 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 Range60° ValueNotes
    High Gloss>70 GUIf measurement exceeds 70 GU, change test setup to 20°
    Medium Gloss10 - 70 GU
    Low Gloss<10 GUIf 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. Three types of instruments are available on the market: 60° single angle instruments, a combination of 20° and 60° and one type that combines 20°, 60° and 85°.

    Many international technical standards are available that define the method of use and specifications for different types of glossmeter used on various types of materials including paint, ceramics, paper, metals and plastics. Many industries use glossmeters in their quality control to measure the gloss of products to ensure consistency in their manufacturing processes. The automotive industry is a major user of the glossmeter with applications extending from the factory floor to the repair shop.

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