Causes and treatment methods of white rust on galvanized coils

I believe everyone is familiar with galvanized coils and galvalume coils.

   But how much do you know about the problem of white rust on galvanized/galvanized products?    When galvanized products are stored and transported in a humid environment, since there is no free flowing air on the surface, the surface of the coating is prone to electrochemical corrosion, and white or gray powdery corrosion products, namely white rust, appear.
   Although white rust generally does not have much impact on the anti-corrosion performance of the coating, if it is exposed to a humid and closed environment for a long time, white rust may become serious, thus affecting the appearance and service life of the product.    Here is a summary of the causes of white rust, as well as some prevention and treatment measures.
1. Causes of white rust:
   By observing products with white rust, we found that areas with mild white rust still have a hot-dip galvanized layer of sufficient thickness to protect the steel base, while areas with severe white rust have almost completely consumed the coating and cannot provide protection.
   Because the moisture adhering to the surface of the coating reacts with oxygen, carbon dioxide, and other oxides in a closed environment, a corrosive aqueous solution will be produced that adheres to the surface of the coating to form an electrolyte, thereby producing a white powder. White rust.
   The severity of white rust depends on the composition of the condensation water and the duration in the environment.
2. Prevention of white rust:
   1) Several desiccants can be placed during packaging

   2) Precise packaging of steel coils, waterproof paper + plastic film + outer packaging of steel coils

   3) Maintaining a low humidity environment and adequate ventilation around the steel coil can reduce white rust

3. Treatment of white rust
   1) Slight white rust can be dried in a ventilated place for a period of time and wiped off with a dry cloth.
   2) Moderate white rust can be removed with a hard-bristled brush (note that wire brushes cannot be used).
   3) For severe white rust, lightly sand it with sandpaper, and then repair it with special galvanized repair paint (special galvanized repair paint is a high zinc paint with a zinc content of more than 95%).