Anodizing Aluminum and Other Metals: Everything You Need to Know

When producing metal components, it is critical to consider the surface finish. Metal finishes enhance the overall appearance of the part and can help improve performance by raising factors such as corrosion resistance and wear resistance.

Fremont, CA: Anodizing is a process that increases the natural oxide layer on the surface of a metal part to form an anodic oxide film. This extra thickness protects the surface of the part and improves its aesthetics.

Although aluminum and titanium are commonly anodized metals, other nonferrous metals can also be anodized. According to the MIL-A-8625 anodizing standard, there are three types of anodizing:

Type I: Makes a very thin oxide layer with chromic acid.

Type II: Sulfuric acid creates a thicker oxide layer suitable for coloring.

Type III: The same process as Type II, but with a thicker oxide layer. This is commonly referred to as "hard anodizing."

There are two classes of MIL-A-8625 types: Class 1 (non-dyed anodization) and Class 2 (dyed anodization) (dyed or colored anodization).

During the anodizing procedure

Anodizing is the process of immersing the metal in an electrolytic bath. A submerged cathode (negatively charged electrode) causes hydrogen to be released from the solution, while oxygen is released at the aluminum part's surface (positively charged anode). This procedure results in the formation of a protective layer of aluminum oxide. The aluminum oxide layer is directly bound to the part's surface, resulting in a very durable, strong finish. While other methods of applying color treatments to aluminum parts, such as painting, are available, they result in a much weaker bond with the surface.

The Advantages of Anodizing Aluminum and Other Metals

Anodizing aluminum, titanium, and other metals have numerous advantages. These advantages can be classified into four broad categories:


Anodizing a metal component increases its lifespan by improving abrasion and corrosion resistance.

Because of this increased durability, anodized metal parts wear out much more slowly during installation, handling, and regular use.


A clear anodized finish can be used to protect a part's already acceptable appearance, or it can be used to add color to the aesthetics.

While precise color accuracy and repeatability require significant expertise, the results can be highly desirable and professional.

Safety and Health

Anodized finishes are chemically stable, non-toxic, and have very few adverse or hazardous effects on land, air, or water. As a result, anodizing is regarded as an environmentally safe procedure. In addition, anodized aluminum can still be recycled like untreated aluminum, lowering its environmental impact further.


Anodizing metal components can have a significant economic impact in the long run. Compared to untreated aluminum, anodizing typically reduces the amount of long-term maintenance, resulting in significant cost savings. Furthermore, while the chemical reactions involved in the anodizing process are complex, the process itself is relatively inexpensive.