Common Defects in Industrial Painting and How to Prevent Them

In the process of industrial coating, the quality of the coating directly affects the appearance, durability and protective performance of the product. However, due to the influence of various factors, various defects often occur in the coating process. This article will introduce several common defects in industrial coating and their prevention methods in detail to help enterprises improve coating quality and production efficiency in the use of automatic coating lines.

Ⅰ. Sagging

Phenomenon description: Sagging refers to the coating flowing downward under the action of gravity during the coating process due to excessive coating thickness or improper construction, forming an uneven coating.

Causes:

•Low viscosity of the coating or excessive addition of diluent.

•The distance between the spray gun and the surface of the object to be coated is too close, and the gun speed is too slow.

•The construction environment temperature is low and the coating takes a long time to dry.

•The coating interval is too short and the flash drying is insufficient.

Prevention methods:

•Strictly control the construction viscosity of the coating to avoid excessive diluent.

•Improve the operator's operating skills, control the gun speed and spraying distance.

•Increase the temperature of the spray booth to speed up the drying of the coating.

• Strictly follow the construction process to ensure sufficient drying time.

Ⅱ. Orange peel

Phenomenon description: Orange peel refers to the uneven surface of the coating similar to orange peel.

Causes:

• The viscosity of the paint is too high and the diluent ratio is improper.

• Uneven spraying and too small a paint output.

• The construction viscosity is too high and the leveling of the coating is poor.

Prevention methods:

• Adjust the viscosity of the paint and increase the proportion of slow-drying diluent.

• Improve the performance and operation skills of the spraying equipment to ensure uniform spraying.

• Adjust the construction viscosity, add leveling agent, and improve the leveling of the coating.

Ⅲ. Pinholes

Phenomenon description: Pinholes refer to small holes on the surface of the coating, which are usually caused by bubbles in the paint or the coating dries too quickly.

Causes:

• Air is mixed into the paint or the solvent evaporates too quickly.

• Improper cleaning and pre-treatment of the substrate.

• The coating is too thick and the solvent is not easy to evaporate.

Prevention methods:

• Improve the defoaming performance of the paint to avoid mixing with air.

• Strengthen the cleaning and pretreatment of the substrate.

• Control the coating thickness to ensure that the solvent is fully volatilized.

IV. Peeling/shedding

Phenomenon description: Peeling/shedding refers to the loss of adhesion between the coating and the substrate or another coating, resulting in flaky or scaly detachment on the coating surface.

Causes:

• Improper surface treatment of the substrate and the presence of pollutants.

• Mismatched coating material selection and incomplete curing.

• High humidity in the construction environment and damp coating.

Prevention methods:

• Thoroughly clean and roughen the substrate to improve adhesion.

• Select appropriate coating materials to ensure complete curing.

• Control the humidity of the construction environment to avoid damp coating.

V. Shrinkage/fisheye

Phenomenon description: Shrinkage/fisheye refers to crater-like holes or dents on the coating surface, usually due to changes in the surface tension of the coating or the presence of pollution sources.

Causes:

• Impurities or pollutants are mixed in the coating.

• Silicon-containing organic compounds exist in the spray painting environment.

• The primer contains mismatched ingredients.

Prevention methods:

• Thoroughly clean the paint and painting equipment to avoid impurities.

• Do not use silicon-containing polishes in the paint shop.

• Make sure the ingredients of the primer and topcoat match to avoid incompatibility.

Common defects in industrial coatings are varied, but as long as the correct prevention methods are mastered, the coating quality and production efficiency can be effectively improved. Through strict control of the coating process and in-depth understanding of the performance of the coating, companies can produce products with beautiful appearance and strong durability to meet customer needs and expectations. At the same time, strengthening employee training and technical exchanges are also important ways to improve coating quality. For more knowledge about the coating industry, consult Attractivechina.