What are the factors of flash rust during the construction of waterborne metal paint?
- 2019-07-23-

There is no specific reason for the flash rust in the construction process of the waterborne metallic paint. It has also been suggested that it refers to the phenomenon of rust spots in the new construction of water-based metallic paints during the drying process, which is mainly manifested in the corroded interface or the newly activated steel appearance.

The occurrence of flash rust may be related to the dissolution and precipitation of iron compounds. The severity of flash rust mainly depends on the coating system. For example, polyvinyl acetate latex at low pH, low temperature and high humidity will prolong water and base. The contact moment of the material is prone to the problem of flash rust.

Of course, there are other different sayings. In fact, the film formation of waterborne metallic paints has a process. Any piece of metal is not pure and smooth, and thus a small block of different potentials will occur, and between different potential blocks There will be an electric current, and metal oxidation will occur to form a rust spot, that is, flash rust."

It can be seen from these different statements that the occurrence of flash rust is actually an electrochemical process. Since the waterborne metallic paint itself is a conductor, it constitutes a charge transfer passage between different regions where the potential difference exists, so that the corrosion occurs in a short time of the process of forming the aqueous metallic paint, thereby forming flash rust.

Obviously, the longer the wet paint film adheres, the more serious the flash rust phenomenon, which can explain the more serious flash rust phenomenon under low temperature and high humidity conditions.

In fact, it is mainly because flash rust is an electrochemical phenomenon, so the vivid metal in front of the hydrogen element will encounter this problem when using waterborne metal lacquer construction.

In the coating test of steel, cast iron, aluminum and aluminum alloy, galvanized sheet and other substrates, we found that the general situation of flash rust is cast iron, aluminum, carbon steel, zinc plate, tinplate, iron plate or wire. , aluminum alloy.

The reason for this situation can be explained from the vivid state of the metal and the purity of the material. The cast iron contains many impurities and the components are disordered, which makes it easier to form a cell with different potentials, thus making it more in the process of water-based metal paint construction. Simply present the situation of flash rust. Electrochemical phenomenon is the root cause of flash rust, but the conditions of flash rust in the construction process of waterborne metal lacquer are very messy. In addition to the difference in the substrate mentioned above, the PH value of the coating, the temperature and humidity of the construction environment, the wind speed, the thickness of the paint film, etc. all have an effect on the flash rust phenomenon.