The main defects of amino electrostatic topcoat are as follows:
1. There is a lot of paint mist flying
For electrostatic paint, the paint mist scatters more, resulting in less deposition and thinner coating film. Reason analysis: First, the voltage is too low when spraying and the electrostatic attraction is small; Second, the rotating speed of the rotary cup or disc is incorrect or the spraying distance between the Spray Gun and the workpiece is too far; Third, the position of the shielding plate is improper. The paint particles are repelled or Caused by the workpiece being too close to the ground. Solutions: First, increase the voltage to within the specified range; Second, determine the appropriate speed according to different coatings and adjust the spraying distance; Third, move the position of the negative shielding plate to prevent repulsion, and the workpiece should be at least 100 cm above the ground.
2. The atomization of paint mist is not good
Poor atomization of paint mist can easily cause particles or roughness in the paint film. The reasons are as follows: First, the speed of the spray cup or disc is too low; Second, the compressed air pressure is low or the voltage is too low. Solution: Increase the speed, increase the pressure and use a higher voltage.
3. The coating film is too thin
The coating film is too thin to affect gloss and hiding power (testing instrument: hiding power paper). Reason analysis: If the paint is too thin, the voltage is too low, or the shielding plate is installed improperly, the paint repulsion is serious and the deposition amount is insufficient. Solution: Increase the viscosity to increase the ejection volume, increase the voltage or improve the position of the shielding plate.
4. The coating film is too thick
If the coating film is too thick, defects such as orange streaks will easily occur (testing instrument: coating Thickness Gauge). Reasons: One is that the paint is too thick and the spray volume is large; the other is that the transmission speed is too slow and so on. Solution: reduce the viscosity of the paint, reduce the spray volume, and increase the transmission speed.
5. Uneven coating
Uneven coating film is prone to uneven gloss or exposed bottom. Reason analysis: The shape of the workpiece is too complex, with holes, pits or corners, etc., the surface of the workpiece is oily or the voltage is too low. Solution: For workpieces with too complex shapes, use ordinary Spray Guns for spraying. For oil-stained workpieces, first effectively remove them before spraying. When the voltage is low, the voltage should be increased.
6. Poor coating leveling
Poor leveling of the coating film can easily lead to uneven thickness or even wrinkling of the coating film (testing instrument: leveling meter). Reason: The thinner volatilizes too fast and the paint film is too late to level, or the paint is too thick and the spraying speed is uneven. Solution: Adjust the type of thinner, pay attention to the spraying viscosity and spraying method.
7. The coating film flows and hangs
The cause of running and sagging is the same as that of general amino topcoat, and the solution is the same as that of amino topcoat.
8. There are impurities in the coating film
You can refer to the relevant content on defects caused by amino topcoats.
9. Poor coating adhesion
Poor adhesion of the coating film means that the coating film is easy to fall off under a slight external force (testing instrument: adhesion Tester). One is that the paint film has aged and become brittle due to over-baking; the other is improper coating matching, such as spraying other paints on the surface of asphalt paint; the third is that the bottom layer is too smooth, the voltage is too low, or the bottom layer is oily. . Solution: Strictly control the baking temperature and time, prevent over-baking, and pay attention to coating matching and construction quality.
10. Poor coating gloss
You can refer to the content related to the defects of general amino paint or other paints (testing instrument: gloss meter )
