Galvanized, galvannealed, galvalume and electro-galvanized bonderized: When it comes to coated sheets and coils, do you know what sets these protective coating processes apart from each other?

We all know that it is important to protect against corrosive substances reaching your metal. When it comes to the methods by which to do so, there are a few to explore.

Let's take a look at four types of coating specifcations; galvanized, galvannealed, galvalume and electro-galvanized bonerdized. As a good rule of thumb, the end use should ultimately determine the type of coated sheet and surface condition required. 


First things first: What is the process of galvanization? These sheets are continuously hot dip coated with a durable protective coating of zinc. It can be formed without flaking or peeling, and the protective qualities cannot be impaired by such actions as stamping, cold drawing, double seaming and brake or roll forming. Galvanized sheets can be welded and soldered.

One important consideration when it comes to galvanized sheets is the thickness. For example, thicknesses of 16 gauge and lighter are lock-forming quality, while thicknesses of 14 gauge and heavier are commercial quality.

Click here for more information on galvanized carbon sheets.


They are heat treated after coating to produce zinc-iron alloy and eliminate the spangle. Galvannealed sheets can be painted without further surface preparation aside from normal cleaning. These sheets may be subject to bending and simple forming without impairing their paintability or corrosion resistance. The coating weight is A60 or A40.

Galvannealed sheets are particularly suited for sign boards, metal doors and partitions, truck and trailer bodies, and heater and furnace parts, among others.

Click here for more information on galvannealed carbon sheets.


They are corrosion resistant, continuously hot dipped coated with an aluminum zinc alloy. When compared with G90 galvanized sheets in some applications, galvalume offers a substantial increase in corrosion resistance.

Appliance and automotive parts, along with metal buildings and agricultural parts, are among the most common applications for galvalume.

Electro-galvanized bonderized

These sheets are cold rolled steel sheets zinc coated by electrolytic deposition and conform to A591.

If your application will require outdoor exposure, painting is recommended. The coating has a dull gray matte appearance without the spangles normally present on hot dipped galvanized. The surface has been phosphate treated for immediate paintability.

Electro-galvanized bonderized sheets can be formed, rolled or stamped without flaking, powdering, peeling or cracking. They have the same gauge thickness as cold rolled sheets.
Cabinets, signs, light fixtures, or anywhere else that an excellent finish is required, are a good fit for electro-galvanized bonderized sheets.

Click here for more info on electro-galvanized bonderized.

When it comes to knowing your coatings for coil and sheet, there is more that goes into the names galvanized, galvannealed, galvalume and electro-galvanized bonderized than you may realize. Take a good hard look at the types of conditions to which your end product will be exposed in order to help ease the final selection process. 

The Gauge Ideas