Six Major Causes and Solutions for Peeling of Polyurethane Paint Topcoat

Polyurethane paint topcoat is widely used in situations such as chemical corrosion, ships, and steel structures due to its excellent chemical and water resistance as well as good film performance.

During use, some problems are inevitable, and the most serious is paint peeling. Now let's analyze the causes and solutions of polyurethane paint topcoat peeling.

Insufficient surface treatment of polyurethane paint topcoat substrate

The oil stains, dust, and unevenness on the surface of the substrate before construction are not cleaned properly. The roughness of the substrate is insufficient, causing the adhesion of the primer to decrease, resulting in the peeling of the polyurethane paint topcoat film.

Solution: Clean the substrate before construction, remove the oil stains, dust, and other impurities on the surface using a thinner or cleaner, and increase the roughness of the substrate surface through sanding. The primer can be applied after the substrate surface is dry.

Failure to clean after the primer of the polyurethane paint topcoat is completely dry

After the primer is applied, the topcoat is not applied for a long time due to various reasons, and the surface of the primer is not cleaned and sanded.

Solution: The requirements for the surface of the substrate by the polyurethane paint topcoat are not high. Generally, the topcoat can be applied after the primer is dried. If the surface of the primer needs to be sanded and cleaned after it is completely dry.

Excessive amount of thinner used during the formulation of the polyurethane paint topcoat

The paint is too thin, resulting in a thin film when brushing, causing poor adhesion of the paint.

Solution: Strictly control the amount of thinner added, add a small amount, and the dilution degree should be less than 5%. After stirring well, test spraying. If the dilution is not enough, add more, following the principle of adding less but multiple times.

Poor covering ability of the polyurethane paint topcoat

Solution: According to the specific situation, switch to other types or brands of paint.

The topcoat of polyurethane paint is applied before the primer is completely dry

The shrinkage of the primer during drying causes cracking and peeling of the topcoat.

Solution: Follow the construction requirements and apply the topcoat after the primer is completely dry, usually within 1-2 hours, without rushing.