An Apple patent (number 20110017602) for dual anodization surface treatment has appeared at the US Patent & Trademark Office. A metal surface treated to have two anodized layers or regions may be used in future electronic devices from Apple.

The surface treatment may include performing a first anodization process to create a first anodized layer, removing the first anodized layer at select locations, and performing a second anodization process to create a second anodized layer at the select locations. The first and second anodized regions may have different decorative properties, such as color, and different structural properties, such as degree of abrasion resistance. One of the anodization processes may be hard anodization and the other may be standard anodization. The inventor is Jivan K. Zhosla.

Here's Apple's background and summary of the invention: The present invention relates to treatments for a surface of an article and an article with a treated surface. More particularly, the present invention relates to performing dual anodization treatments to the surface of a metal article and a metal article with a surface having two distinct anodized layers or regions.

"Many products in the commercial and consumer industries are metal articles, or contain metal parts. The metal surfaces of these products may be treated by any number of processes to alter the surface to create a desired effect, either functional, cosmetic, or both. One example of such a surface treatment is anodization.

Anodizing a metal surface converts a portion of the metal surface into a metal oxide, thereby creating a metal oxide layer. Anodized metal surfaces provide increased corrosion resistance and wear resistance. Such characteristics are important to consumers because they want to purchase products that have surfaces that will stand up to normal wear and tear of everyday use and continue to look brand new. Anodized metal surfaces may also be used in obtaining a cosmetic effect, such as utilizing the porous nature of the metal oxide layer created by anodization for absorbing dyes to impart a color to the anodized metal surface. Accordingly, there is a continuing need for new surface treatments, or combination of surface treatments, for metal surfaces to create products that will protect the appearance of the metal surface while also achieving a desired aesthetic appearance.

"A surface of a metal part or article may be treated to create dual anodized layers or regions having different properties. The two anodized layers may be different colors or may have different degrees of scratch or abrasion resistance. One anodized layer may be decorative in nature and the other anodized layer may be structural in nature. The dual anodized layers or regions may be applied to a broad range of metal articles including, electronic components, household appliances and cookware, automotive parts, and athletic equipment.

"In broad terms, the dual anodized layers or regions are created by performing a first anodization process on the surface of a metal part or article to create a first anodized layer, removing the first anodized layer at select locations, and performing a second anodization process to create a second anodized layer at the select locations. One of the first and second anodization processes may be a hard anodization process to create a hard anodized layer or region and the other of the first and second anodization processes may be a standard anodization process to create a standard anodized layer or region."

-- Dennis Sellers
dsellers@applecentral.com