1. Introduction
Gloss is the optical property of the surface of an object, which indicates the ability of the surface of the object to reflect light. In the field of painting, the gloss of the coating film is the ability of the surface of the coating film to reflect light, also known as mirror gloss. The gloss of the coating film is not only related to the properties of the coating itself, but also affected by the incident ray source, light angle, etc. Gloss is divided into three categories: glossy, semi-glossy and matte. Different gloss is suitable for coating applications with different needs, such as automotive coatings, furniture paints, etc.
2. Relevant standards
GB/T 9754-88 and ISO 2813:1994 are standards for the determination of gloss of coating films, which specify methods for gloss measurement using geometric angles of 20 °, 60 ° and 85 °.
3. Introduction to the main points of the inspection method
3.1 GB/T 9754-88 Determination of 20 °, 60 ° and 85 ° mirror gloss for paint films without metallic pigments
3.1.1 Test principle
The gloss meter uses the principle of optoelectronics to measure the specular reflected light on the surface of the paint film. What the gloss meter measures is the intensity of the reflected light of the paint film within a certain angle range, which is related to the material of the paint film and the angle of incidence of the light. In the measurement, the light emitted by the light source passes through the lens and becomes parallel light, and then projects it on the measured surface at a certain angle. The measured surface will reflect the light at the same angle, and it will concentrate on the photoelectric pool through the lens to generate a photocurrent, which can be read by the galvanometer.
3.1.2 Operational Points
Sample preparation: Apply the paint to the glass plate using a 100μm wet film preparer to ensure that the paint film is flat.
Gloss Determination: Measure three readings at different locations on the test paint film parallel to the coating direction, calibrating the instrument with a high gloss working standard plate to ensure accuracy. If the error is less than 5 units, record the average as the gloss value. Otherwise, perform three measurements and record the average and limit values of all six values.
Non-glass substrate: Six measurements were made in different areas or directions on the surface of the sample, and the average and limit values were recorded. If the error is greater than 10 units or greater than 20% of the average value, the test plate is discarded or the average and limit values are recorded.
3.1.3 Results show
Use the gloss unit value at a certain angle to represent the gloss of the paint film.
4. Application and meaning
The gloss measurement of paint film is an important method to evaluate the appearance performance and quality of paint. Gloss measurement results can help understand the decorative properties, protective properties and surface smoothness of the coating film, so as to ensure that the coating effect meets the design and quality requirements.
5. Conclusion
Measuring the gloss of a paint film is a key means of evaluating the appearance characteristics of a coating film. Through gloss measurement, the gloss of the coating film can be objectively and accurately evaluated, thereby providing reliable data for the quality control of the coating project and ensuring that the coating film meets the requirements of design and standards. Coating manufacturers and the coating industry can use gloss measurement methods to improve the quality and appearance of products.
