Understanding Anodizing: Why Class II is the Industry Standard

When it comes to aluminum in glazing systems, the finish is crucial for both aesthetics and long-term durability. Anodizing is the most common finishing process for architectural aluminum—it not only enhances colour and corrosion resistance but also strengthens the surface.

However, not all anodized finishes are created equal. The anodizing class you select impacts the appearance, durability, and consistency of your entire system, and whether components like flashings and frames appear consistent once installed.

What’s the difference between Class I and Class II Anodizing?

Class I

With a minimum coating thickness of 0.7 mil (18 microns), it is a heavier-duty option, Class I anodizing is built for demanding environments—think coastal areas or locations with heavy pollution and wear. It offers superior corrosion resistance and a richer color due to its thicker oxide layer.

Class II

At 0.4 mil (10 microns) thick, Class II anodizing is the industry standard for commercial construction. It delivers reliable durability and a matte finish, making it ideal for storefronts, curtain walls, and aluminum flashings where a uniform look and performance are essential.

Finish Options that Fit the Industry:

At IMARK, we use Architectural Class II anodizing products for our flashings that glazers require. The reason for that is precise alignment.

Most window and curtain wall systems are finished to Class II specifications. By matching that spec on our flashings, we help ensure a seamless appearance between frame and perimeter. This means:

• No visible differences between adjacent components

• Fewer finish discrepancies at project close-out

• Consistent performance and durability across the entire system

It’s a subtle detail that often goes unnoticed when executed correctly, yet it significantly enhances the overall quality and professional appearance of the project.

Common finishes include Clear, Bronze (various), Black, Clear Bright Brushed

Final Thought

Choosing a supplier goes beyond cost; it’s about true compatibility—both in the materials you require and in your collaborative process. When the frame and the flashing share the same specification, the glazing system performs and presents as a unified whole.

At IMARK, getting the details right is our top priority.

Have a question about anodizing or glazing products we offer? We are always happy to help! Contact us