Technical service knowledge of wood coating
Paint is a furniture raw material, playing an important role in furniture surface decoration and improvement of furniture taste. Paints which can be used on furniture have different prices. How to judge the performance of the paint? Is the selected paint cost-effective? One can evaluate from the following aspects:
Appearance performance of paint: the appearance performance of paint can be sensed directly, like the levelling property, anti-flux property, drying property, grinding property, color accuracy and other performances.
Inner performance of paint: Evaluation of the inner performance of paint is important index to determine the quality of the paint.
Viscosity index: Viscosity will change greatly with the changes of temperature. Therefore, there may be big difference in viscosity in winter and summer, which does not mean that the quality of the paint is unstable. This is usually a misunderstanding of some furniture manufacture on paint.
Non-volatile content index: also called solid content, it is the only index on the effective component in paint. Currently, there is a misunderstanding in the furniture industry that the higher the viscosity of the paint is, the more the paint is cost-effective because more water can be added. But this fails to consider the effective component of the paint. Actually, all the water added to the paint will volatilize into the air. So the more water is added, the more the water is wasted and the environment is affected. Therefore, paint with low viscosity and high solid content will be the development mainstream of furniture industry.
Hardness: Hardness has 14 grades like 6H, 5H, 4H, 3H, 2H, H, F, HB, 2B, 3B, 4B, 5B, 6B, etc. The hardness of ordinary paint film is between B-3H. The hardness of paint film is just a simple indicator of film performance. Larger hardness does not necessarily indicate better quality.
Adhesive force: Adhesive force is an important indication of the bondability between the paint and substrate and it also indicates whether the paint will peel off in the furniture’s service life.
Warping performance: It is an important indicator of flexibility of paint film which indicates that the paint film will not crack or peel off in the furniture’s service life.
Impact resistance: It is also an important indicator of flexibility of paint film. This indicator is of obvious meaning to metal paint because the better the impact resistance of the paint, the harder will the paint film to be whitened or separated in case of compact.
Cold resistance: It refers to the paint film’s ability to resist cold in low temperature. This performance is a prerequisite in determining if the furniture can be used in the winter of colder area in North China.
Heat resistance: This performance ensures the paint film’s resistance to the heat of hot water, tea pot and other daily articles.
Resistance to temperature variation: This indication is a higher requirement of paint film. Only paint film passing thermal cycling test has the basic condition to be used in any weather.
Yellowing resistance: It indicates the color retention performance of paint film during use. Color difference before and after UV lighting or sunshine is used to determine the color change degree. The smaller the color difference is, the better the color retention performance. The properly design paint film shall have little color change under test conditions.