Mirror Surface Gloss Detection Method | Gloss Measuring Instrument

Different mirrors have different gloss levels due to their ability to produce specularly reflected light on the surface. This article will briefly introduce the use of a gloss measuring instrument to measure the gloss of a mirror.

1. What is the gloss of the mirror?

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.

2. Use a gloss measuring instrument to check the gloss of the mirror

For commonly used mirror products, in order to control the production quality of the product, it can be measured with a gloss measuring instrument.

In general, a geometric angle of 60 ° gloss measuring instrument 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 gloss standard 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 60-degree angle commonly used on the market is like the universal 60-degree gloss measuring instrument LS192 from Linshang Technology, with a range of 1000GU, high gloss and low Glossy materials can be tested because the gloss is a relative value. When there is no uniform standard in the applied industry, it can be tested with the LS192 instrument. 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.