Thread Content
Low-surface-treatment coatings for metal surface repair. Low-surface-treatment coatings used for repair need to be distinguished from coatings designed for use on rusted surfaces. The main purpose of coatings for rusted surfaces is to be applied to steel surfaces that still have rust on them, whereas low-surface-treatment coatings can be used not only on rusted surfaces but also on other types of old coating surfaces. Such coatings are known as surface-tolerant coatings; they are commonly referred to as low-surface-treatment coatings in the industry. First, we need to understand what is meant by working on surfaces that are rusty. It does not mean applying paint without carrying out any treatment on the rust deposits on the surface. Regarding minimal surface preparation, we must understand what condition the substrate surface can be in and still be considered acceptable – for example, the presence of oxide scales, rust, various old coatings, water, oil, salt, etc. Moreover, the construction environment may feature high or low temperatures, high humidity, and so on; all these factors need to be taken into consideration. Secondly, low-surface-treatment coatings are used in situations where it is not possible to achieve the Sa2.5 level of sandblasting while still meeting high-level corrosion protection requirements; at the same time, such coatings are required to be able to be applied over various types of existing coatings without causing any compatibility issues. In summary, low-surface-treatment coatings can be used for treating ST2/3 surfaces by hand or with power tools, as well as surfaces with existing coatings or those that have been rust removed through high-pressure water jetting. Moreover, since these products are primarily used for maintenance purposes, they must be more capable of withstanding various climates and unusual operating conditions than other products. The coating must have the following properties: good penetration and adhesion (modified epoxy), good corrosion resistance (due to pigment addition), minimal impact on existing coatings (high solid content with little effect from solvents), sufficient flexibility (to accommodate expansion of existing coatings), and tolerance to harsh weather conditions (ability to be applied at low temperatures, as well as in conditions of moderate humidity or even with a small amount of water on the substrate).