What is double anodizing?

Two-color anodizing is a special metal surface treatment process that allows the formation of two different colors of anodic oxide films on the same metal part.

This process is usually used for aluminum alloys, which have good anodizing properties. With two-color anodizing, it is possible to create a unique visual effect on the same part, enhancing the aesthetics and recognition of the product.

two color anodizing
two color anodizing

Production method of two-color anodizing

Masking Method

  • Polishing and masking: The metal casing is first polished to a mirror surface and then sprayed to the designated area using photographic ink to form a masking area.
  • First Anodizing: The unmasked areas are sandblasted, then first anodized and dyed to seal the holes.
  • Removal of Masking: The ink is cleaned off the masked area and then the second anodizing is performed, this time on the previously masked area. Since the first anodized areas have already formed a protective film, they will not be affected by the second anodizing.
two color anodizing

Removal method

Primary oxidation coloring: One oxidation coloring of the aluminum alloy, followed by one sealing treatment.

Coloring Oxidation

Removal of oxide film: The surface to be colored for secondary oxidation is treated to remove the oxide film on that coloring surface.

Secondary oxidized coloring: After removing the grease, secondary oxidized coloring is carried out, and finally, secondary sealing treatment is carried out to obtain the finished product.


Sealing is a very critical step in two-color anodizing. When the product is oxidized for two or more times, the sealing work can ensure that the coloring part will not be damaged.

In addition, the anodic oxidation film has a porous structure and high surface activity, so special attention needs to be paid to avoid contamination and damage to the oxidized film in the treatment process.


Two-color anodizing is a complex process that requires precise handling and expertise. It can bring unique color and texture to metal parts, but it also requires strict quality control and fine process management.

For which metals is the two-color anodizing process applicable?

The two-color anodizing process is mainly applicable to aluminum alloys. This process can form two different colors of oxide film on the same product, thus creating a unique visual effect.

Aluminum alloys are often used in a variety of industrial and consumer products due to their lightweight, high strength, and corrosion-resistant properties, and anodizing further enhances their surface hardness, abrasion resistance, and aesthetics.

In addition to aluminum alloys, certain other metals such as titanium, niobium and magnesium alloys can also be anodized, but they are not as widely used as aluminum alloys.

What are the advantages of two-color anodizing over regular anodizing?

Color Diversity

Two-color anodizing can form two different colors of oxide film on the same metal surface, providing more visual effects and design freedom to meet the needs of personalization and customization.

Decorative Effect

Due to the uniqueness of the two-color effect, the products treated with two-color anodic oxidation are more outstanding in terms of decoration, which can attract consumers’ attention and increase the added value of the products.

Technical Difficulty

Compared with ordinary anodizing, two-color anodizing is technically more difficult and requires precise control of electrolysis conditions and dyeing process, which makes it more costly than ordinary anodizing in terms of technical level and cost.


Two-color anodic oxidation technology is widely used in the fields of architecture, automobile, electronics, etc., especially in products requiring personalized design, such as high-grade furniture, decorations, automobile interior and exterior parts, etc.

machcncmaster anodizing service

Mach CNC Master provides professional two color anodizing services. We use advanced technology and equipment to create high quality two-color anodized products for our customers.

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