Anodizing is one of the most common surface treatments of aluminum. In all anodizing processes, the basic reaction is conversion of the aluminum surface to aluminum oxide. The aluminum part, when made anodic in an electrolytic cell, causes the oxide layer to become thicker, leading to better corrosion and wear resistance. For decorative purposes, the oxide layer formed on the surface can be dyed.

In aluminum anodizing processes, the basic reaction is a conversion of the aluminum surface to aluminum oxide, including Type I—Chromic acid anodizing, Type II—Sulfuric acid anodizing, Type III—Hard coat anodizing. 


Fixing Corrosion Between Anodized Aluminum and Steel

Anne Deacon Juhl, Ph.D., with AluConsult, says Galvanic corrosion is due to an electrical contact with a more noble metal or a nonmetallic conductor in a conductive environment.

Anodizing: Essential Reading

Maximizing the Service Life of Process Tanks

PVDF liners have a proven history with delivering end users longer lasting, lower maintenance plating tanks.

How to Minimize Fading of Anodized Colors

All color-anodized parts fade, but if the process is optimized, you can expect years with minimal loss in color, says Reliant Aluminum Products’ Mark Jozefowicz.

How to Apply the 720 Rule to Current Density Anodizing

What can you tell me about the 720 Rule as it applies to current density anodizing? Plating expert Sjon Westre, Ph.D., from Chemeon, answers this question.

Differences in Masking and Plug Materials

Q. Can you explain the differences between masking caps and plugs?

Better Alloy Control of Alkaline Zinc Nickel Baths

The factors that influence nickel content in deposits from alkaline non-cyanide zinc nickel baths.


FAQ: Anodizing

What is anodizing?

Anodizing refers to a broad range of surface treatments commonly applied to various grades of aluminum and titanium to provide cosmetic and functional benefits.

What is a cold seal?

A cold seal, also known as a room-temperature seal, is a sealing bath that contains nickel and fluoride and is used at ambient temperatures. Best results are obtained with temperature regulation, which ensures a more consistent rate of sealing reaction. Recommended sealing temperatures for Clariant cold seal products are between 80° and 90°F (27° to 32°C).

What is the best anodizing seal process for my operation? 

Sealing of anodized aluminum is considered the most important of the various steps in the anodizing process. How you seal determines the performance of the anodic oxide in its end-use environment. After the anodic oxide layer is formed, there are a number of sealing options that exist, including unsealing, high temperature, mid-temperature, and room-temperature or cold sealing.

How do I evaluate anodized aluminum?

  1. Film thickness measurement
  2. Curvature 
  3. Edge Effect
  4. Base metal thickness
  5. Surface roughness
  6. Conductivity
  7. Quality of Seal


Anodizing Suppliers