What is the purpose of cleaning metal surfaces before painting?

Cleaning metal surfaces before painting is primarily aimed at facilitating adhesion of subsequent layers. For paint to adhere effectively to a metal surface, it must be free from contaminants such as dirt, oil, grease, rust, and old paint. These contaminants can create a barrier that prevents proper bonding between the paint and the metal, leading to issues such as flaking, peeling, or premature failure of the paint system.

By ensuring that the surface is clean, the paint can form a stronger bond, leading to improved durability and performance of the coating. This cleaning process can involve various methods, including solvent cleaning, abrasive blasting, or chemical cleaning, depending on the degree of contamination and the specific requirements of the paint system being used.

While quicker drying, changing the color of the metal, and aesthetic improvements may be aspects that are influenced by the painting process, they are not the primary reasons for cleaning the surface before applying paint. The crucial factor is achieving proper adhesion to ensure the longevity and effectiveness of the coating.