| Sulfuric anodize, commonly referred to as Type II anodizing, is formed by using an electrolytic solution of sulfuric acid at room temperature and a current density of 15 to 22 Amps per square foot. The process will run for 30 to 60 minutes depending on the alloy used. This will produce a primarily clear coating, depending on sealing. Typically 1/2 of the coating thickness will build up per surface and 1/2 will be penetration.
Type II sulfuric anodizing provides for several desirable qualities such as:
- Corrosion Resistance (336+ hours salt spray resistance per ASTM B117)
- Surface Durability
- Excellent Dye ability (yielding deep, rich colors)
- Electrical Insulation
Sulfuric anodize coatings are often sealed to enhance corrosion resistance, lock in dyes, or both. There are hundreds of governmental, industrial, and commercial anodizing specifications in use, each with their own method of specifications for coating, seals, dyes, etc. Any anodizer should recognize the Type II designation to indicate a sulfuric anodize, Class 1 to specify natural color or no dye, and Class 2 to indicate a dye. This anodizing meets Mil-A-8625. Sulfuric anodizing is rather tolerant of aluminum alloys for anodizing with the exception of high-silicon die-cast alloys such as 380. The less alloying elements there are the higher the clarity and depth of color of the anodize coating.
Elite Metal Finishing can provide a wide variety of colors. Some colors include clear anodizing, black, red, blue, and gold. If you have a special color to match, call us for professional assistance. |
