Difference Between Type II and Type III Anodizing for Aluminum Machined Parts

Type II and Type III Anodizing for Aluminum Machined Parts

Are you wondering which type of anodizing is best suited for your aluminum machined parts? The choice between Type II and Type III anodizing can significantly impact the durability, cost, and appearance of your components.

In this blog post, we will delve into the distinctions between these two methods, from the science behind each process to their practical applications.

By the end of this read, you’ll understand precisely which type of anodizing aligns with your project’s requirements and why. Get ready to make an informed decision that could enhance the performance and aesthetics of your aluminum machined parts.

What is Anodizing and How Does It Work?

Anodizing is a transformative electrochemical process that enhances the natural oxide layer on aluminum parts. By submerging aluminum into an acid electrolyte bath and passing an electrical current through the medium, a robust oxide layer forms on the surface of the metal. This process increases the material’s durability and wear resistance and enhances its corrosion resistance, making anodized parts ideal for various demanding applications.

Additionally, anodizing allows for color customization through dyeing, providing aesthetic flexibility alongside functional benefits. This combination of traits makes anodizing a preferred finishing technique in industries ranging from aerospace to consumer electronics.

Click the link to learn more about anodizing vs. electroplating.

Type II Anodizing

Type II anodizing, often celebrated for its decorative flair, transforms aluminum into a canvas of color. This process involves submerging the aluminum parts in a sulfuric acid bath where an electrical current is applied, forming a thin oxide layer on the surface. This layer is not just a pretty face; it increases corrosion and wear resistance while allowing for vibrant dyeing options.

Ideal for components that won’t face extreme conditions but still require durability, Type II finds its home in consumer goods, automotive interiors, and architectural details. The real charm of Type II anodizing lies in its ability to turn functional metal parts into eye-catching pieces, offering a wide palette of colors that can match any designer’s vision.

Type III Anodizing

Type III anodizing, also known as hard anodizing, is the heavyweight champion in the anodizing world. This process involves a similar electrochemical method as Type II but operates at cooler temperatures and higher voltages, creating a much thicker oxide layer. This rugged coating, which can be up to 0.005 inches thick, turns aluminum parts into durable powerhouses capable of withstanding harsh environments.

Ideal for industrial applications such as aerospace aluminum components, military hardware, and surgical tools, Type III excels where failure is not an option. 

Compared to Type II, it offers superior wear resistance and corrosion protection but lacks the same vibrant color options, often resulting in a darker, more subdued finish.

anodizing aluminum parts

Comparative Analysis: Type II vs Type III Anodizing

When choosing between Type II and Type III anodizing, think of it as deciding between a sporty convertible and a rugged SUV; each has its scenario where it shines. So, what’s your project calling for? Let’s break down the differences:

FeatureType II AnodizingType III Anodizing
Process ParametersModerate electrical currents, standard temperaturesHigher voltages, cooler temperatures
Coating Thickness0.00007-0.001 in. (1.8-25 μm)0.0005-0.006 in. (13-150 μm)
DurabilityGoodVery Good
CostLess expensiveMore expensive due to process demands
Typical Use CasesConsumer goods, automotive interiorsAerospace, military, industrial applications
AestheticsWide range of colors, glossy finishLimited colors, darker and more subdued finish

Process Parameters: Type II uses standard conditions with moderate electrical currents, perfect for achieving that glossy, colorful finish. On the flip side, Type III, our hard anodizing heavyweight, involves cooler temperatures and higher voltages to create a tougher, thicker oxide layer.

Coating Thickness: Type II usually ranges from 0.00007 to 0.001 inches thick, offering a lightweight protective layer. Type III steps it up to about 0.0005 to 0.006 inches, providing a barrier that’s not just thicker but also packed with durability.

Overall Durability and Cost: If durability is your endgame, Type III is your go-to, albeit at a higher cost. It’s built to last against extreme wear and corrosion, making it ideal for more demanding applications. Type II, while cost-effective, provides moderate protection and is best suited for less aggressive environments.

Typical Use Cases: Where do you plan to use these anodized parts? Type II is great for interior design or automotive interiors where style meets mild conditions. Type III is the hero for aerospace, military, and other industries where parts face tough challenges.

Aesthetics: Do you want your parts to pop with color? Type II allows for a spectrum of hues, enhancing both the function and the flair of parts. Type III, while limited in color options, offers a sleek, professional look with its darker finish.

Considering these points, which type feels right for your project? Whether it’s the resilience of Type III or the colorful versatility of Type II, your choice will significantly influence the performance and appearance of your aluminum parts. Let’s navigate this decision together!

Choosing Between Type II and Type III Anodizing

Deciding between Type II and Type III anodizing hinges on a few critical factors: durability needs, aesthetic preferences, and environmental conditions. If your parts require high wear and corrosion resistance in tough environments like aerospace or industrial settings, Type III’s robust coating is ideal.

For projects where aesthetics are key, and conditions are less severe—such as in consumer goods or automotive interiors—Type II offers a wide range of colors and sufficient protection at a lower cost.

Always align your choice with industry standards to ensure your components meet operational demands.


In this blog, we’ve explored the nuances of Type II and Type III anodizing for aluminum machined parts, delving into their distinct processes, applications, and benefits. Type II anodizing offers aesthetic flexibility and moderate protection, making it ideal for less demanding environments. In contrast, Type III anodizing provides superior durability and resistance, suitable for harsh conditions and critical applications. Your choice between these types should align with your specific needs and industry standards.

Interested in customizing your aluminum parts with a durable and attractive finish? Contact us today! We offer a variety of surface finishes for aluminum CNC parts, tailored to meet your project requirements.


Which grade of aluminum is best for anodizing?

The ideal aluminum alloy for anodizing depends on the specific anodizing process and the intended use of the component. Commonly used alloys include 6061, 6082, and 6063. These alloys are favored for most applications due to their excellent corrosion resistance and good analyzability, making them versatile choices for various anodizing needs.