Paints and varnishes Determination of 20°, 60° and 85° specular gloss of paint films for paints and varnishes without metallic pigments (GB/T9754-88) This standard is equivalent to the international standard ISO2813-1978 "Paints and varnishes- Determination of 20°, 60° and 85° specular gloss of paint films without metallic pigments».
(1) Subject content and trial scope
This standard specifies the method for measuring the specular gloss of the film at geometric angles of 20°, 60°, and 85°.
The 60° method is suitable for all paint films, but the 20° or 85° rule is more suitable for paints with a high degree of glare or near matte paints.
The 20° method can improve the identification ability for high-gloss paints, and is suitable for paints with a 60° gloss higher than 70 units.
The 85° method can improve the discrimination ability for low-gloss paints, which is used for paints with 60° gloss below 30 units.
These methods are not suitable for determining the gloss of paints containing metallic pigments.
(2) Instrument
① Glossmeter: It consists of a light source part and a receiving part. The light source passes through the lens so that the parallel or slightly converging light speed is directed to the surface of the paint film of the test panel. The reflected light is converged by the lens of the receiving part, and absorbed by the light pool through the field of view diaphragm.
②Standard plate
(3) Test method
① At the beginning of each operation, first adjust the instrument and calibrate the gloss meter so that it can correctly read the gloss value of the high-gloss working standard plate, and then read the gloss value of the low-gloss working standard plate. If the instrument transition number of the low-gloss working standard plate differs from the specified value by more than 1 gloss unit, it is better to use it after readjustment by the manufacturer. After operating for a certain period of time, the gloss meter also needs to be calibrated to ensure the stable operation of the instrument.
② After the gloss meter is calibrated, take 3 readings at different positions of the test paint film parallel to the coating direction, and then calibrate the instrument with a high-gloss working standard plate to ensure that the reading wave is well prepared. If the error range of the result is less than 5 units, record the average value as the specular gloss value, otherwise perform three measurements and record the average value and limit value of all 6 values.
③Using this method to measure the gloss, the paint breakage on the surface with good smoothness is only meaningful. Because the phase microbending or local unevenness of the substrate will seriously affect the measurement results.
