ISO 2813:2014 pdf free

ISO 2813:2014 pdf free.Paints and varnishes – Determination of gloss value at 20°, 60° and 85°
Gloss is a visual perception caused by looking at surfaces. The specular reflection of objects is even more distinct when light is reflected more directionally from the surface. The incident light is reflected on high-gloss surfaces only in the main specular direction. On matt surfaces the light is not only reflected in the main specular direction but also diffusely scattered in all solid angles. The more uniformly the light is scattered into the space the smaller is the intensity of the directed component and the matter the surface appears.
The principle of gloss measurement is based on the measurement of the directionally reflected light. In this context its intensity is measured in a defined angular field around the reflection angle. The intensity of the reflected light depends on the surface material and the incident angle. Accordingly, on coated surfaces with increasing incident angle more light is reflected. The remaining light is refracted at the interface air/coating, and within the coating diffusion and/or absorption of the light occurs.
The gloss values are not related to the intensity of the incident light but to the reflection properties of a black, polished glass standard with specified refractive index.
For different viewing angles the gloss perception can vary widely. For example matt surfaces can appear glossy under grazing incidence of light and low viewing angle, because under these reflection conditions a lot of light is reflected directionally and also the intensity of diffusion is low.
Figure 1 ilustrates the relation between the gloss perception of visually equally clasified coating specimens (from matt to glossy) and the assigned gloss values for the measuring angles of 20° ,60° and85°
EXAMPLE Visual classification 9 corresponds to 35 GU under 20°, 70 GU under 60 and 95 GU under 85°.
The course of beam of the glossmeter is ilustrated in Figure 3. The light of a source is collimated onto the test surface at a specified angle, and the reflected light is received by a lens at the same angle and focused onto a photo detector.ISO 2813 pdf download.