The amount of light that is projected onto the film surface at a certain incident angle and reflected at a corresponding angle is glossiness. The test principle is shown in Figure 3-8-1.
At a certain incident angle, the film surface is rough, the flatness is poor, the scattered light is more, the reflected light is less, and the glossiness is low. The film gloss measured by 60% gloss is classified as follows:
| High gloss | ≥70% |
| Half / medium gloss | 30%~70% |
| eggshell gloss | 6%~30% |
| flat gloss | 2% ~6% |
| no gloss | ≤2% |
As the incident angle increases, the intensity of reflected light increases. According to ASTM D523, for high gloss films exceeding 70%, a 20 ° incident angle gloss measurement should be used. Conversely, for low gloss films below 30%, 850 gloss measurement should be used.
According to ISO 2813, the gloss range measured by the 60 gloss meter is 30% to 70%. For high gloss, both 20 ° and 60 ° gloss data need to be given. At this time, for ease of use, a multi-angle (or variable angle) gloss meter can also be used to measure glossiness under different incident rays.
For glitter paints, a multi-angle Spectrophotometer can be used to test the flash effect. Such as the MA58 (25 °, 45 °, 75 °) and MA68 (150, 259, 45 °, 75 °, 110 °) of the American x-Rite series. The incident ray remains unchanged at 45 angles, and the reflected light intensity is detected at different viewing angles [see Figure 3-8-2 (a) ]. When the aluminum powder is arranged in parallel in the film, the mirror reflection has the maximum reflected light intensity, and the larger the reflection angle of the deflected mirror, the scattered light is enhanced, and the reflected light received is weakened [see Figure 3-8-2 (b) ]. In the spectrum of Photocell, photovoltaic cell light intensity signal and observation angle, if the peak is higher and the Peak width is narrower, when viewed at different angles, the more intense the light and shade change of the reflected light, the stronger the flickering effect of the flash paint, and the better the flash effect.
For the glitter paint color difference, available Japan MI a NOLTA CR353 (25 °, 95 °) two viewing angle and CR354 (15 °, 45 °, 110 °) three viewing angle Colorimeter to determine.
