Galvannealed Or Galvanized? Choosing Your Coating

Posted on: 3 June 2016

If you're working on an engineering or art project for school and are looking at using sheet metal as one of your materials, you've no doubt learned how coating the metal can protect it from corrosion, as well as making it easier to use if you plan to paint the metal. However, you've also likely found that there are different types of coatings that can affect how the metal lasts. Two major types are galvanized metal and galvannealed metal; galvanized has a coating that's mostly zinc with some aluminum, and galvannealed has iron thrown into the mix. Which type you choose can greatly affect your finished project.


Both galvanized and galvannealed metal can be painted, but galvannealed holds the paint a little better. There's less chance of the paint flaking off if the metal is painted correctly. If the project you're working on calls for painting the metal and ensuring that the paint lasts a long time -- in other words, it won't just be a temporary installation that you dismantle and throw away -- you want galvannealed metal, and you want to use paint and primer that are meant to be used on metal.


The addition of iron also helps make galvannealing a lot stronger and less susceptible to damage. If the project is something that's going to take a lot of hits -- not necessarily because people are trying to hit it, but because it could get some nicks and scratches in the course of being moved, for example -- galvannealed is the way to go.


However, galvannealing's thickness and strength don't lend themselves well to flexibility. If you need to bend the metal, especially into very tight bends and corners, plain galvanized metal is a better bet. It's much more flexible and able to withstand those bends without breaking the galvanized coating.


Another distinct advantage of galvanized coatings over galvannealed coatings is that you don't have to paint galvanized metal for it to look good. The iron in galvannealed coatings can sometimes lead to discoloration -- the metal is fine, but it looks corroded because of the discoloration. That means you have to paint galvannealed metal if you want it to look good. Galvanized metal isn't subject to that discoloration because there's no iron in the coating.

If you want to see samples of the two coatings, talk to sheet metal manufacturers and see if they have any variations that might be of use. Adding sheet metal to a project, especially if you're going to cut the metal, isn't an easy task, and you want to reduce the chances of having to replace the metal.

For more information, contact Rogers Brothers Galvanizing or a similar company.