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The most common mechanism underlying the adhesion of paint coatings is the van der Waals force adsorption theory. In actual coating applications, this mechanism plays a role in almost all cases of adhesion. The reasons why the van der Waals force adsorption theory is so common are as follows: This mechanism does not impose any specific requirements regarding the type of substrate or the coating system; as long as the paint can fully wet the substrate, reducing the distance between the coating molecules and the substrate molecules to an effective range of 0.3–0.5 nm, van der Waals forces can arise between these molecules, thereby enabling adhesion. This basic condition is met in almost all painting scenarios. Even with the additional contributions of other mechanisms (such as chemical bonds and mechanical interlocking), van der Waals forces remain a component of the fundamental adhesion force; therefore, they are the most widely used adhesion mechanism. The limitations of the applicability of other mechanisms: Compared to other mainstream mechanisms, the universal advantage of van der Waals forces is quite evident: Mechanical adhesion: It is only applicable to substrates with a rough surface and pores, and its contribution to smooth and flat substrates is limited ； Chemical bonding: It can be established only if both the coating and the substrate possess reactive functional groups; not all systems meet these conditions ； Hydrogen bonding: Requires matching specific polar groups, and hydrophilic groups affect water resistance; it serves only as an auxiliary enhancement mechanism ； Diffusion: Applicable only to polymer systems with good affinity; it has little effect on inorganic substrates ； Electrostatic interaction: It can only exist in specific systems where a double layer can be formed, and its contribution is extremely small. In actual coating applications, van der Waals forces are generally used as the source of adhesion, with other mechanisms working together to enhance the overall adhesion strength.