Anodizing that Withstands H2O2 Cleaning
Testing color anodized finishes in hydrogen peroxide gas plasma sterilization.
Color anodized aluminum is widely used as a material in the medical device industry. From tool handles to trays, these repeat-use devices undergo regular cleaning and sterilization treatments and it is vital that the original finish remain preserved throughout.
Several types of sterilization methods are in use today, but those that incorporate hydrogen peroxide injection are particularly challenging for a color anodized finish to endure, since fading or significant discoloration typically occurs after only a few sterilization cycles.
Here, we explore various coloring and sealing treatments exposed to one such method of sterilization: Sterrad. Manufactured by Advanced Sterilization Products in Ervine, Calif., it’s a system that uses low-temperature hydrogen peroxide gas plasma technology to sterilize instruments and medical devices. Which treatments for anodized aluminum can hold up to multiple rounds of Sterrad?
Anodized aluminum can be colored using a variety of technologies that can loosely be divided into two classes: organic and inorganic.
Organic colorants, or dyes, are by far the most widely used for decorative finishes. The porous anodized aluminum is simply dipped in a dye bath, and over time, dye is absorbed into the surface. The color range is virtually endless as dyes are used at any number of depths of shade and in any combination.
Dyes tend to be large organic molecules that may contain a metal ion. Every dye is unique and has its own fastness characteristics, but all fade to some degree as a result of bond cleavage within the organic molecule. This cleavage can occur as a result of UV irradiation, chemical oxidation or a combination of both.
The dyes chosen for this study were taken from Clariant’s Sanodal range of super high fastness products, dyes that have been developed, tested and proven durable enough for extended outdoor use.