When you’re deciding on how to finish your aluminum extrusions, there are different options to consider. One such option is an anodized finish.

So, What is Anodization? And Why Would You Want an Anodized Finish for Your Extrusions?

Aluminum has a naturally occurring oxide film that protects it from corrosion. Anodization is a process extruders use to thicken this film. They place the profiles into a solution and pass a low voltage, high amperage, direct current through them.

Anodization Will:

  • Increase corrosion resistance.
  • Increase resistance to wear.
  • Create a porous surface ideal for accepting dyes
  • Provide better adhesion for paint primers and glues.

Anodization Will Not:

  • Increase the strength of the aluminum itself.
  • Have high conductivity in the anodization layer.

One of the Most Common Reasons to Anodize – Dying

In the photo below, you can see two carabiners that have been dyed blue and red after anodization.

Aluminum Carabiners with an Anodized FinishFor designers looking to apply colors to their extrusions, anodizing can be an ideal solution. When aluminum is anodized it creates a porous surface in the oxidation layer. That surface is perfect for applying dyes.

The dye seeps into the pores. Then, once the dye has been applied, the pores can be sealed. This locks in the dye and it becomes like part of the aluminum itself. Because the dye is embedded in the oxidation layer, the color will not peel or fade with sunlight.

[Image: Wikimedia Commons]

 

Can Anodizing Improve Corrosion Resistance?

Improving corrosion resistance is one of the key purposes of anodizing. It helps to extend the life of the aluminum and makes it ideal for harsh environments. Anodized extrusions have been used in marine environments and even up in space!

Will Anodizing Decrease Electrical Conductivity?

Some applications require conductivity. And an anodized finish will decrease conductivity in the oxidation layer. If you want to achieve both conductivity and corrosion resistance, you can “dual-finish” your aluminum extrusions.

This means that you can both anodize the aluminum and also do chromate conversion coating. This combination will allow you to achieve conductivity along with the added corrosion resistance.


Learn About Other Finish Types

For more information about other finishes, take a look at these 6 types of aluminum finishes.