Low surface treatment coatings must first be distinguished from rusty coatings. The main function of the paint with rust is to coat the steel surface with residual rust, and the low surface treatment paint introduced in this article can not only be painted with rust, but also can be coated with other kinds of old coatings. In English, this type of coating is called surface-tolerant coating, literally translated as surface-tolerant coating, and according to industry practice, it is called low surface treatment coating.
Due to the particularity of this type of paint, if the text is misinterpreted, it will bring adverse consequences. For example, with the rusty paint in the past, many people think that the rust products can be painted with paint without any treatment, or they have different understandings about the degree of rust treatment. For low surface treatment coatings, we need to understand what the state of the substrate surface is that can be tolerated, which is the most important. For example, the surface of the substrate may be covered with scale, rust, old coatings of various components, moisture, salt or oil. Such coatings may also require the ability to tolerate high-low temperatures, relative humidity, and surface moisture during application. These factors must be carefully considered before using low surface preparation coatings.
In actual coating construction, it is impossible to carry out completely effective sandblasting treatment on steel in many cases. In addition to the special situation of the steel structure itself, there are increasingly strict environmental protection regulations and health and safety regulations. For example, the maintenance and painting of bridges will affect the public and pollute water sources if sandblasting is carried out.
The use of low surface preparation coatings is mainly aimed at situations where it is not possible to fully achieve blasting grade Sa 2½ (ISO 8501-1: 1988), but also to achieve a high level of corrosion protection. Another requirement is that low surface preparation coatings can be applied over different types of old coatings without compatibility problems. Therefore, in this context of discussion , low surface preparation coatings are primarily those coating products that can be applied to hand or power tool polished surfaces (St2/St3), old painted surfaces and high pressure water jet deGraduation surfaces .
Since low surface treatment coatings are mainly used in painting maintenance, this type of coating products also needs to be more adaptable to various climates and construction environments than other types of coating products. Those standard shop application requirements are not suitable for low surface preparation coatings. High humidity, low temperature, wind, dust, and dew and micro-condensation on substrates and coatings may all be problems encountered during on-site construction of steel structures.
High-pressure water jet rust removal has attracted more and more attention during painting maintenance, because it does not generate a large amount of dust like sandblasting, causing environmental protection problems, and does not need to build strict enclosure structures. In ship maintenance, high pressure water jet rust removal has many applications and has achieved great success. The application practice of low surface treatment paint on high pressure water jet derusting surface shows that it is the most suitable paint product.
