Clear Coat For Galvanized Steel

Question:

Our company is the leading fence and mechanical tube producer in the Caribbean basin. The above-mentioned markets call for an additional coating that is well known as a "lacquer." This type of coating protects the tubes generally stored in a yard exposed to several weather conditions such as rain and dust which are conducive to white rust at early age.

In order to add more physical attributes to our product, we are looking for an extra-quick-drying transparent lacquer coat or substitute product to be applied in our tube mills running at 250 ft/min. Could you advise us with a coating product and application technology? F.R.

Answer:

Clear "lacquers" to protect galvanized steel from white corrosion in storage are commercially available products. These lacquers range from actual coatings of organic films to crystalline inorganic films. Most paint and metal pretreatment companies will supply it. Two items to consider when using these products are cleaning the surface before application and compatibility with zinc.

The galvanized steel must be clean, that is, free from dirt and oily soils. It cannot have the usual coat of wax, which is also used for corrosion protection and normally applied at the mill. You don't have this problem because you are the mill. Some organic coatings react with zinc, causing blisters and loss of adhesion. The paint or metal pretreatment supplier can recommend the correct coating for this application.