What are the common coating defects? How to repair them?

In the coating process, coating defects are common problems. They not only affect the appearance quality of the product, but may also affect the durability and performance of the product. Here we share several common coating defects, including solvent bubbles, sagging, color difference, etc., and provide corresponding repair methods.

1. Common coating defects and repair methods

a. Solvent bubbles

Solvent bubbles refer to small bubbles and bubble marks on the paint surface. This is mainly caused by too short flash-off time between coating and drying, or too fast temperature rise during drying. To repair solvent bubbles, you can use 2000 sandpaper to grind the defective surface. If the defect can be polished off, polish it after smoothing; if the defect cannot be polished off, use P320 sandpaper to thoroughly polish and re-spray the mid-course primer.

b. Sagging

Sag refers to the local thickening of the paint surface, which usually occurs on surfaces with large inclination angles or vertical surfaces. Sagging may be caused by too thick a paint film, insufficient paint viscosity, too low a temperature at the spraying position of the workpiece, or oil stains on the primer. Slight sags can be ground with a grindstone or 2000 sandpaper until smooth and then polished; large areas of sags need to be polished with P500 dry sandpaper before re-spraying.

c. Color difference

Color difference is a common problem in painting, which may be caused by many factors such as inaccurate color matching, poor painting environment or incorrect spraying method. To repair color difference, first use P500 sandpaper to dry grind the surface, then adjust the color correctly, and re-spray using transition spraying techniques. Before re-spraying, you can first spray a color plate with the adjusted paint, and then spray the body after comparing it with the body.

2. The role of coating line equipment in preventing defects

a. Optimization of coating line

The coating line is an important part of the coating process, and its design and operation directly affect the coating quality. In order to avoid coating defects, the coating line should have good temperature and humidity control, particulate matter filtration and exhaust gas treatment capabilities. Temperature and humidity control can ensure that the paint is dried in a suitable environment to avoid problems such as solvent bubbles and sagging; particle filtration can keep the coating environment clean and reduce defects caused by impurities; exhaust gas treatment can ensure that the exhaust gas generated during the coating process is effectively discharged to protect the environment.

b. Maintenance of coating equipment

The performance of coating equipment is crucial to the quality of coating. Equipment such as spray guns, paint pumps, and filters should be regularly maintained and maintained to ensure that they are in good condition. For example, spray guns should be cleaned regularly to avoid uneven spraying caused by blockage and paint residue; paint pumps and filters should be regularly checked and replaced to prevent impurities in the paint from affecting the quality of coating. In addition, the selection of coating equipment is also very important, and appropriate equipment should be selected according to the type of coating and the requirements of the coating process.

c. Training of operating skills

In addition to the optimization of coating lines and coating equipment, the skill level of operators is also a key factor affecting coating quality. Enterprises should regularly train operators to improve their operating skills and professional knowledge. The training content should include the selection of coatings, spraying techniques, equipment operation and maintenance, etc., to ensure that operators can master the requirements of the coating process and reduce the occurrence of coating defects.

Coating defects are an important factor affecting product quality and appearance. By understanding common coating defects and their repair methods, as well as the key role of coating line equipment in preventing defects, companies can take effective measures to improve coating quality. What other coating knowledge do you want to know? We will share it in the next article!