Structural steel anti-corrosion paint, also known as workshop primer, is used during the processing stage in workshops. It provides temporary protection for the metal substrate before surface treatment like sandblasting and phosphatizing, and before the application of rust-preventing primer. The general protection period is about 3 months, not exceeding half a year. Annual spraying control is low, with film thickness controlled below 20um. The width of welding burn-through should be ≤15mm, ensuring it does not affect cutting, welding, and other processes. Common types include acrylic pre-coated primer and epoxy pre-coated primer.

To meet the adhesion requirements with the substrate, suitable rust-preventing primers must be chosen for different substrates. Epoxy-based primers offer excellent corrosion resistance and are highly adaptable to various substrates, making them widely used as rust-preventing primers and capable of satisfying most corrosion and rust prevention needs. Common types include two-component epoxy primers (zinc phosphate, zinc-rich, zinc yellow), polyurethane primers, single-component alkyd rust-preventing primers, epoxy ester primers, and chlorinated rubber primers, among others, which are also frequently used as general rust-preventing primers.

The intermediate paint, positioned between the primer and topcoat, boasts excellent filling properties, capable of repairing and improving the substrate of the primer, thereby enhancing the overall spray effect. Typically, it is a semi-gloss paint with a sheen of around 60, which facilitates the detection of any defects in the film after the primer is applied, allowing for repairs prior to the topcoat application. It also enhances decorative qualities and saves on topcoat usage, making it a suitable choice for coatings with high corrosion resistance or decorative requirements. Common types include two-component epoxy intermediate paint, epoxy iron oxide intermediate, and polyurethane intermediate paint, etc.

The requirements for the surface paint include excellent weather resistance, resistance to corrosion by environmental media, and superior decorative properties. High standards are set for luster, color, resistance to aging, resistance to chemical media, scratch resistance, and leveling. For coatings on projects with high decorative requirements, it is generally necessary to apply a clear topcoat to enhance the decorative appearance. Common types include weather-resistant acrylic magnetic paint, acrylic polyurethane topcoat, fluorocarbon topcoat, and sometimes clear topcoat based on decorative requirements.