How To Tell if Sheet Metal is Galvanized or Not

Closing The Manufacturing Skills Gap In America
March 4, 2016
National Metal Fabricators: A Solution Company
March 14, 2016
Show all

How To Tell if Sheet Metal is Galvanized or Not

As an industry, we’ve come a long way in terms of sheet metal quality over the years. Customers demand materials that are reliable and able to withstand tough conditions. Galvanization is one method that sheet metal manufacturers use to bring customers top-quality products. With most metal fabricators, you know upfront whether the material you’re using has been galvanized. However, in other cases, you might have to do a bit of your own inspecting to be sure. A basic understanding of galvanization can help you to determine whether the sheet metal you are using is right for your application. Read below to learn more.

What is galvanization?

In short, galvanizing is a way in which to corrosion-proof a metal. There are multiple ways to do it, but the end result is typically the same: a metal that is coated in corrosion-resistant zinc. The layer of zinc acts as a buffer to protect the more vulnerable metal underneath from rusting. How is it done?

– Hot-dip galvanizing involves immersing iron or steel into molten zinc. It’s among the most basic methods, although for some applications, it can result in a zinc layer that is too thick.

– Electroplating sometimes referred to as electro-galvanizing, coats a metal by way of sending an electric current through it. This method is common for metal used in vehicles and other heavy machinery.

– Thermal diffusion is a process in which the metal is heated with zinc powder. Once hot enough, a zinc-iron alloy will form on the metal’s surface.

How to Tell Whether Metal Has Been Galvanized

How do you know the difference? Many manufacturers can tell just by looking, because galvanized and non-galvanized appear slightly different. For example, when metal has been galvanized, it will appear slightly lighter in color than non-galvanized; and whereas non-galvanized is shiny, galvanized will look a bit duller.

The surface texture of the two types looks different, as well. Galvanized metals sometimes appear to have tiny silver flakes on the surface — described by some observers as appearing to ripple. Up close, it will appear a bit grainier than non-galvanized metals because of the zinc coating.

Ultimately, performance will be your giveaway. For example, if you have a piece of metal that is not fresh out of manufacturing, and it is not painted and does not appear to be rusting, it is likely galvanized.

When Is Galvanized Preferred?

As a rule of thumb, if rust is a concern, then you want galvanized. Galvanized metal can suffer from shallow nicks and abrasions without exposing the more rust-sensitive metal beneath it. That makes galvanized metal ideally suited for heavy machinery and hardware. At a consumer level, galvanized iron and steel are used for such applications as ornaments and decorations for outdoor metalwork, door and window hoods, and much more. However, certain materials (such as plasters and cements containing chlorides and sulfates) can damage galvanized steel, as can acid rainwater rolling off wood shingles. Be sure to consult a qualified metal fabricator to determine all pros and cons of galvanized metal before beginning your project.