The Differences in Type II And Type III Anodizing

At Sapphire Metal Finishing, we work with OEMs and various manufacturers to provide customized solutions for their aluminum anodizing requirements. Many of our customers are unsure of the difference between Type II and Type III anodizing and which option is best for their parts and components.

There are some basic questions to consider that will help determine if the Type II or Type III anodizing is the best choice. Of course, our team is always here to help, and we can answer any questions you may have about specific applications and components for use in atypical types of environments and applications.

Cosmetic or Functional

One of the first considerations is the reason for the anodizing process. When the appearance of the part is a primary concern, Type II anodizing is the best option. This provides a virtually transparent surface on the aluminum. It can be left as is, or it can be dyed in a second process. With the clear background, the color of the dye will be true on the aluminum, creating consistency in all colors in and between batches. Because this transparency, colors are deep, rich and bright.

Type III anodizing results in a gray to dark, almost black surface on the aluminum, depending on thickness. Thinner Type III anodizing can be dyed, but the colors are muted. The dark nature of the anodizing and the pore shape is not as conducive to dye coloring and can result in problems in achieving consistency and the desired colors.

Corrosion Resistance

Type III anodizing offers thicknesses that are up to four times as thick as Type II anodizing film. The Type III film is also much denser. This significantly increases the wear resistance of the part. The thicker film and narrower pores increase the corrosion resistance of the, which is an important consideration when used in harsh conditions.

The Type III anodization also offers better dielectric strength, which is a key consideration in electronics applications.

For more specific information based on your needs, call us today at 208-614-4050. We would be happy to help.