The gloss of a mirror refers to its ability to produce specular reflection on the surface. The brightness of the mirror reflection is determined by the sharpness and flatness of the surface of the object. All bright, highly reflective surfaces are called specular or shiny.
Gloss, as the surface characteristic of an object, depends on the surface's ability to specularly reflect light. The so-called specular reflection refers to a reflection phenomenon with the same reflection angle and incident angle. Gloss is a physical quantity that evaluates the ability of a material's surface to reflect light under a set of geometrically prescribed conditions.
For the gloss measurement, it is a standard relative measurement using highly polished black glass with a refractive index np = 1.567 as a reference. Assuming that the surface is in an ideal polished state, the plane can specularly reflect the speed of natural light and define a gloss value of 100.0 gloss units at this time. Then when measuring the surface gloss of other objects, it is usually expressed by multiplying the reflectance of the sample in the specular (orthogonal) direction relative to the standard surface by 100, that is, G = 100R / R. Therefore, the gloss of the mirror is generally compared with the standard plate to calculate the gloss value, and there is no fixed size.
For commonly used mirror products, in order to control the production quality of the product, it can be measured with a gloss meter.
In general, a geometric angle of 60 ° can be used to measure most samples and determine whether the measurement angle is appropriate. The 20 ° geometric angle can be used to measure high-gloss objects, and the 85 ° geometric angle is suitable for measuring low-gloss objects.
The nominal gloss value determined by this method can be obtained by comparing the specular reflection of the sample with the standard black specular reflection. Because the specular reflection also depends on the refractive index of the sample surface, the measured gloss nominal value also changes with the surface refractive index. However, in order to obtain a nominal gloss value, the specular reflection of two samples with similar surface refractive indices is usually compared. Because the nominal value of the instrument is more affected than the visual value that bends with the surface refractive index, when comparing the surfaces of high-gloss samples with different refractive indices, the visual inspection is not consistent with the nominal value of the instrument gloss.
The general angle on the market is a 60-degree angle. Like the general-purpose 60-degree gloss meter LS192 from Linshang Technology, the range reaches 1000GU. High-gloss and low-gloss materials can be tested because gloss is a relative value. When applied When there is no uniform standard in the industry, the LS192 can be used for testing. If the industry has a uniform standard, it is best to use the same angle of testing. Therefore, when choosing a mirror to measure the angle, you should choose differently according to different situations.