ISO 7668 Anodizing of Aluminum and Its Alloys - Specular Reflection and Specular Gloss of Anodic Oxidation Coatings at 20, 45, 60 or 85 Degree Angles

Material Testing

ISO 7668 Anodizing of Aluminum and Its Alloys - Specular Reflection and Specular Gloss of Anodic Oxidation Coatings at 20, 45, 60 or 85 Degree Angles

EUROLAB laboratory provides testing and compliance services within the scope of ISO 7668 standard. Developed by the International Organization for Standardization (ISO), the ISO 7668 standard is 20° (Method A), 45° (Method B), 60° (Method C) and 85° (Method D) and an additional 45° method using a narrow acceptance angle (Method E) specifies methods for the measurement of specular reflection and specular gloss of flat samples of anodized aluminum using specular reflection geometries.

ISO 7668 Anodizing of Aluminum and Its Alloys - Specular Reflection and Specular Gloss of Anodic Oxidation Coatings at 20, 45, 60 or 85 Degree Angles

The methods described are primarily intended for use with transparent anodized surfaces. They can be used with colored anodized aluminum, but only with similar colours.

Specular reflection and specular gloss are not unique physical properties of a surface. They vary with the measuring angle and the aperture dimensions that describe the incident and reflected rays, such that measurements of these features are not independent of the apparatus used.

The specular reflection of most surfaces increases with the measuring angle and takes into account the use of reflectometers with various angles, eg for painted surfaces. However, the specular reflectance properties of anodized aluminum do not always behave normally, and due to the double reflection property, the reflected light comes partly from the film surface and partly from the underlying metal.

For a full understanding of the reflective reflection properties of the anodized surface, it is recommended to measure the reflective reflectance properties at 20°, 45°, 60° and 85°, and careful thought should be given as to which method or methods are most appropriate. in any special case. The specular reflection of bright anodized aluminum with a mirror finish is best measured using 45° or 20° geometry.

Specular Reflection is the ratio of the luminous flux reflected in the specular direction to the luminous flux of the incident light for a given source and receiver angle. It is usually expressed as a percentage.

Mirror Luminance is the ratio of the luminous flux reflected from an object in the specular direction to the luminous flux reflected from glass with a refractive index of 546,1 at a wavelength of 1.567 nm for a given source and receiver angle.

To set the reflective gloss scale, polished black glass with a refractive index of 1.567 is assigned a value of 20 for geometries of 45°, 60°, 85° and 100°. The phenomenon of reflecting light of anodized aluminum is very different from that of black glass, and the choice of the standard of black glass is arbitrary and is made to allow comparison of different grades of anodized aluminum.

Among the services provided by our organization within the framework of material testing services, there are also ISO 7668 standard tests. Do not hesitate to contact our laboratory EUROLAB for your testing and certification requests.

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