The galvanization of steel is a process in which a protective layer of zinc is applied to the steel to make it more durable. One of the popular methods of this galvanizing is hot dip galvanizing, where the steel is dipped into a hot molten zinc. This process has been used for years to protect steel from corrosion and there are many companies who offer hot dip galvanizing services.
However, these hot dip galvanizing services have emerged into the more advanced duplex system. This is basically the way of powder coating the steel after hot dip galvanization. The moment paint and galvanized steel are infused together, the corrosion control becomes stronger thereby protecting the base steel by providing a barrier along with a cathodic protection. Moreover, galvanization prevents the development of iron-oxide, preventing the paint to blister and peel off faster. The paint also slows down the rate of zinc damage.
Characteristics of Coating
It’s important to know the characteristics of steel after galvanizing. It starts to react the moment it’s out of the molten zinc. So, it depends on the environment. Based on this situation galvanized steel is divided into three parts. Newly galvanized, partially weathered and fully weathered. Each of this requires duplex coating, but slightly different from the other, because of the surface material and different characteristics of galvanized steel.
Preparing Hot Dip Galvanized Steel for Powder Coating
The preparation of the hot dip galvanized steel for powder coating or painting involves two steps which are as follows.
Cleaning: The cleaning is done to remove the dirt from the surface. However, it’s important to do this task carefully, because highly acidic or even basic cleaning sometimes scrapes off the zinc from the surface. There are a few types of cleaning methods, like
- Ammonia cleaning -This is used to clean the parts with ash residue that are left behind because of galvanizing.
- Alkaline cleaning – Oil, grease and dirt can be removed with this alkaline solution cleaning.
- Solvent cleaning – Cleans all the volatile compounds.
Profiling: To provide a good adhesion to for the paint, it requires the galvanized steel surface to be slightly roughened or ridged.
These two things are to be done perfectly, only then the powder-coat or the paint will stick to the steel. There are 4 types of the profiling method-
- Abrasive sweep or brush blast – To roughen the galvanized surface this method is used.
- Acrylic passivation – This method is used to passivate the galvanized surface.
- Conversion coating – Enhances the durability and adherence of the paint.
- Paint formulations – This is an alkyd formulation used as the paint.
The galvanizing of steel is an advanced way to make the steel durable and strong. With the advanced method of powder coating or painting, this process has become more advantageous for a long-lasting use.