Frequently Asked Questions

Q: What is Aluminum Anodizing?
A: Aluminum anodizing is an electrochemical process in which an oxide (anodic) layer is chemically built on the surface of the metal. This oxide layer acts as an insulator and can be dyed in a wide variety of colors. Anodizing provides surface corrosion protection along with an excellent substrate for decorative finishes.

Q: Why is Aluminum Anodized?
A: Bottom Line: To apply a coating to the softer aluminum thereby protecting it. Aluminum oxidizes very quickly, and rapidly forms an aluminum oxide coating that inhibits further oxidization. This coating is useless as is, in terms of protecting the metal, because it is so thin. A thicker coating can be produced by immersing the part in an electrolytic solution and passing an electrical current through it, similar to electroplating. The resulting film is nearly colorless, and can be easily dyed because it is very porous at the molecular level. It also results in a heavy aluminum oxide film and has a hardness similar to that of a ruby or sapphire. When aluminum is anodized, direct electrical current (DC) is passed through a bath of sulfuric acid while the part being treated serves as the anode. This produces a clear film of aluminum oxide on the part's surface. Electron microscopy indicates that this layer is mostly porous with a very thin barrier layer at the base. This structure lends itself very well to electrolytic coloring or absorptive dying. During the anodizing process, many controls are critical to guarantee the specified film thickness, its abrasion resistance and density. These controls include a precise combination of chemical concentration, temperature and current density. In the production of quality anodized products, there is no alternative to having sophisticated monitoring equipment and highly-trained, experienced personnel.

Q: What is anodized aluminum used for?
A: Because anodizing is such a versatile process there are literally thousands of different applications. These applications include but are not limited to:

• Aerospace
• Department of Defense products
• Recreational vehicles
• Architectural products like windows and doors
• Appliances
• Automotive
• Lighting
• Food preparation equipment
• Furniture
• Sporting goods
• Medical equipment
• Marine
• Construction

Q: Can an Anodized coating be colored?
A:  Yes. The Anodize coating is transparent and is not really a coating but becomes part of the metal surface. Anodized aluminum can be colored many colors.

Q: Can any aluminum be anodized?
A: The short answer is yes. But, some aluminum such as cast are harder and very often do not look good because of silica content, contaminants, etc.