The levelness of coatings, also known as flatness or uniformity, is an important index to measure the decorative performance of coatings. National Standard GB1750-89(79) provides specific methods for determining leveling.
The paint is brushed or sprayed on the base plate with a flat surface according to the general preparation method of the paint film. While the brush opens the template, the stopwatch is activated to measure the time needed for the brush to make the brush mark disappear and form a completely smooth film surface, expressed in minutes.
Spraying with the above method, observe the paint surface to achieve uniform, smooth, wrinkle-free state time. Another method is to adjust the paint sample to the application viscosity, apply it to the sample with primer, make it smooth and even, then in the middle of the film with a brush longitudinal brush a brush mark, observe how much time brush mark disappear, the film is restored to a smooth surface.
Generally according to the film to reach a smooth surface of the time rating: not more than 10 minutes is good; 10 to 15 minutes is qualified; after 15 minutes is not uniform is not qualified (non-decorative coating can not do this requirement)
The evaluation of the leveling performance has a great relationship with the variety and viscosity of the coatings. The leveling performance of high viscosity coatings is generally lower than that of low viscosity coatings. With the development of science and technology, in recent years, many new leveling aids have been gradually applied, such as Polyacrylic acid esters, the overall rheological property and leveling property of the coating can be greatly improved
The more the brush marks or orange peel disappear, the flatter the coating surface, that is, the better the decorative performance. The levelling performance of coatings is related to the composition and proportion of resin, pigment and solvent, and also to the application method.
Post time: Nov-21-2023
