BS EN ISO 7759:2010 pdf download,Anodizing of aluminium and its alloys. Measurement of reflectance characteristics of aluminium surfaces using a goniophotometer or an abridged goniophotometer.
Introduction
The visual appearance of metallic finishes is important commercially on metals for automotive, architectural, and other uses where these metals undergo special finishing processes to produce the desired appearance. For end-products which use such finished metals, it is important that parts placed together have the same appearance. Specular reflectance is one of the properties measured, but additional measurements are usually required to identify adequately the appearance of any metal surface. In the method described in this International Standard, several important aspects of surface appearance are identified and can be measured. Those surfaces having identical sets of numbers will normally have the same reflectance characteristics and the same appearance (see References [1], [2] and [3]).
This International Standard specifies a method for the measurement of the reflectance characteristics of highgloss anodized aluminium surfaces. The method described is also suitable for the measurement of the reflectance characteristics of other highgloss metal surfaces. The method is not suitable for diffuse-finish metal surfaces and does not measure colour.
5.3 Reflectance standards
5.3.1 Three calibrated reflectance standards shall be available.
a) Aluminium evaporated onto plate glass and covered with a protective coating of silicon monoxide, and calibrated for specular reflectance and distinctness of the reflected image. The specular reflectance shall be85%±10%.
b) Chromium evaporated onto plate glass and covered with a protective coating of silicon monoxide and calibrated for specular reflectance and distinctness of the reflected image. The specular reflectance shall be 62 %± 10 %.
c) Reflecting plate with a white diffuse surface from which reflected light has a substantially constant luminance over the angular range of the instrument.
Where the distinctness of the reflected image is being measured, standards intermediate in reflectance and made from anodized aluminium may be useful.
5.3.2 It is essential that standards are kept clean and free from scratches, as well as from contact with contaminating materials. Follow the cleaning method specified by the instrument manufacturer and check standards at regular intervals against reference standards held in reserve.