Gloss is measured by reflecting light at a certain angle on a surface. According to ASTM D 523, 60° is used for normal gloss paint film, 20° is used for high gloss paint film test, and 85° is used for low gloss paint film test.
The gloss of the coating film can be classified as follows (measured with a 60° gloss meter):
High gloss foreign luster ≥ 70%
Semi-gloss or medium gloss 70%~30%
Eggshell light (matte) 30%~6%
Eggshell light to flat light 6% ~ 2%
Flat light≤2%
Gloss is measured on a black polished glass plate with a refractive index of 1.57 relative to a gloss of 100GUs. In actual operation, it is difficult to achieve a gloss of 100GUs, and most commercial standard values are 94~96GUs at 60°. The north and south tides remind you: the gloss meter in the laboratory has a difference of 5GUs, which is not very obvious. After ISO revised the gloss standard in 1991, the standard version remained unchanged, but the value was consistent with ASTM-20°: 9260°: 9585°: 99
