Water-based steel structure paint has certain requirements for the pretreatment of the steel structure surface, which is directly related to the adhesion effect and protective performance of the coating. Compared with some solvent-based oil water-based steel structure paint, it has more stringent requirements on surface cleanliness, because the film-forming process of water-based water-based steel structure paint is greatly affected by water evaporation. If there are impurities on the surface, it is easy to cause pinholes, bubbles or shedding of the coating. Therefore, the core of pretreatment is to remove surface pollutants and provide a clean adhesion basis for the coating.
The oil and grease on the surface must be thoroughly removed, which is the basic step of pretreatment. Oil will hinder the contact between water-based water-based steel structure paint and the surface of the steel structure, resulting in the coating being unable to adhere tightly, and it is easy to peel over time. It is usually necessary to use a special cleaning agent or alkali solution to wipe and spray to ensure that there is no oil residue on the surface. If necessary, it is also necessary to use physical methods such as grinding to assist in removing stubborn oil, so that the steel structure surface can be restored to a clean state and prepare for the subsequent application of water-based steel structure paint.
For the oxide scale and old coating on the surface, pretreatment also needs to be properly handled. Oxide scale is a loose oxide layer naturally formed on steel structure in the air. It is not firmly bonded to the substrate. If it is not removed, the water-based steel structure paint will easily fail as the oxide scale falls off after application. If the old coating has problems such as cracking and bulging, it also needs to be completely removed to prevent the new coating from being affected by the poor condition of the old coating. Only by removing these unstable surface layers can the new water-based coating form a reliable bond with the steel structure substrate.
Regarding the rust problem, it is not an ideal choice to directly apply it on the rusty surface. The loose rust is fragile and has poor adhesion to the surface of the steel structure. The water-based steel structure paint cannot penetrate the rust and effectively bond with the substrate. After the coating dries, it is easy to peel off together with the rust. Especially the thicker rust layer, which may hide moisture and impurities inside, will continue to corrode the steel structure, causing the rust under the coating to spread, but accelerate the damage of the steel structure, and fail to achieve the expected protective effect.
If there is only slight floating rust on the surface of the steel structure, water-based steel structure paint can be applied after proper treatment. It is necessary to use sandpaper or wire brush to thoroughly grind off the floating rust to expose the solid metal surface, and then wipe off the dust generated by grinding with a clean rag to ensure that the surface is dry before applying water-based steel structure paint. This light rust removal treatment can remove the unstable rust layer, allowing the water-based steel structure paint to directly contact the steel structure substrate to form a continuous and complete coating to play its protective role.
During the pretreatment process, the flatness of the surface also needs to be paid attention to. A surface that is too rough or has sharp edges and corners may affect the uniformity of the film formation of water-based steel structure paint, and the coating is prone to be too thin at the edges and corners, reducing the protective ability. If necessary, sharp edges and corners can be blunted by grinding, and obvious depressions or protrusions can be repaired to make the surface flat, so that the water-based steel structure paint can be evenly covered, ensuring a consistent coating thickness and enhancing the overall protective effect.
Water-based steel structure paint has clear requirements for surface pretreatment. It is necessary to remove oil stains, scale, old coatings and thick rust layers to ensure that the surface is clean, dry and solid. For rusty surfaces, they cannot be painted directly. They need to be treated accordingly according to the degree of rust. Slightly floating rust can be painted with water-based steel structure paint after grinding and removal, while thicker rust layers need to be thoroughly rusted. Although strict pretreatment increases the number of preliminary processes, it can significantly improve the adhesion and protective life of water-based steel structure paint, allowing the coating to better play its role in protecting steel structures and avoid coating failure problems caused by improper pretreatment.
