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.
Properties
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.
Hot water seals produce the clearest sulfuric anodize while sodium dichromate yields a yellow-green appearance but
is generally a better seal.
Specification
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.
Materials
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.
Nor-Ell can provide a wide variety of colors. Some colors include clear anodizing, black, red, green
and gold. If you have a special color to match, call us for professional assistance.
Nor-Ell has a unique process of combining multiple colors (black, clear, gold, green etc) all on the same part with their anodizing process to create colorful, durable products to enhance your product and brand recognition. This process can include from two-color to multi-color parts. This process is ideal for face plates, control panels, cover plates, labels and decals. Even your multicolor logos and graphics can all be anodized onto the same part creating striking, durable and unique branding and labeling. For available samples that demonstrate the extensive possibilities for color and graphics, contact Nor-Ell.
