In the production of paints, the selection of wetting agents needs to be combined with the characteristics of pigments, resin systems, and construction requirements. Currently, the commonly used types are mainly classified into the following four categories based on their chemical structures: 
1. Anionic wetting agents
This is one of the most widely used categories in the paint industry. Their molecular structures contain anionic groups such as carboxyl and sulfonic acid groups, which can stabilize the pigment dispersion system through charge repulsion. Typical representatives include sodium dodecylbenzenesulfonate and alkyl phosphate salts. The former has a high cost-performance ratio and is suitable for the dispersion of inorganic pigments in water-based and solvent-based paints, effectively preventing the agglomeration of calcium carbonate and talc powder; the latter has strong alkali resistance and performs well in alkyd resin and epoxy resin paints with high pH values, and can also improve the scrub resistance of the paint film. 
2. Nonionic wetting agents
This type of wetting agent does not contain charges and is not affected by the pH value of the system or electrolytes, having excellent compatibility. Common types include fatty alcohol polyoxyethylene ethers and organosiloxane compounds. Fatty alcohol polyoxyethylene ethers (such as AEO-9) have both wetting and emulsifying functions, suitable for mixed pigment systems, and can reduce compatibility conflicts between different pigments; organosiloxane compounds (such as polyether-modified silicone oil) mainly feature low surface tension and can significantly reduce the surface tension of the paint film in high-gloss topcoat production, avoiding pinholes and fish-eye defects, and improving the smoothness of the paint surface. 
3. Cationic wetting agents
Their molecules contain amino, quaternary ammonium salt, etc. cationic groups, and mainly adhere to the negatively charged pigments (such as carbon black, iron red) through charge adsorption, suitable for special functional paints. For example, hexadecyltrimethylammonium chloride is widely used in conductive paints and anti-corrosion paints, which can achieve uniform pigment dispersion and enhance the adhesion between the paint film and the metal substrate, but due to poor compatibility with anionic resins, it is less used in conventional water-based paints. 
4. Special types of wetting agents
For high-end paint requirements, fluorocarbon-based wetting agents and polymer-based wetting agents are also used. Fluorocarbon types (such as alternatives to perfluorooctyl sulfonate) have extremely low surface tension and are suitable for ultra-durable exterior paints and anti-graffiti paints, providing excellent waterproof and anti-stain properties for the paint film; polymer types (such as acrylic copolymers) stabilize the dispersion system through spatial steric hindrance effects, avoiding pigment sedimentation in nano-pigment paints and high-solid-content paints, and extending the storage period of the paint.