Type II,
Sulfuric Acid Anodizing (SAA)

Most frequently used type of anodizing, this process will generate decorative or protective surfaces with greater durability than surfaces treated with type I. Sulfuric anodize provides a minimum of 336 hours of 5% salt spray resistance per ASTM B117.

Chromic Acid Anodizing

Most common process for commercial anodizing.
Films range from .0001"-.001" thick. The overall thickness of the coating formed mainly in penetration of the substrate (67%). Considering the preparation of the part, etch and deoxidized, there is no modification of the final dimensions of the part. This process adds minimal hardness and abrasion resistance. Sulfuric anodized film can be colored prior to sealing.


Many alloys can be processed. The film is thicker and harder than chromic anodize and even though the surface finish will turn light grey naturally, it can be colored. This type of anodizing is non-conductive and good for bonding.


Used in architectural extrusion and sheets, external structures (curtain wall), optical components, hydraulic valve bodies, as well as military applications, computer and electronic enclosures, mechanical hardware or paint/prime base.

Chromic Acid

Type I, Chromic Acid Anodizing (CAA)

First commercial type of anodizing, widely used in aerospace and defense. It minimises metal fatigue and is compatible with many aluminum alloys.


Type III, Hardcoat Anodizing (HCA)

The primary objective of this process is to obtain a hard coating, resistant to abrasion. It is obtained using an electrolyte of sulfuric acid at low temperature with high voltage and current density.

Boric Sulfuric

BAC 5632 / MIL-A-8625 Boric Sulfuric Anodizing

Developed by Boeing Aerospace as a chrome free alternative to type I, for non-critical fatigue part. The adhesion to paint is equal or superior to Type I and this type of anodizing provides corrosion protection.