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Does Aluminum Alloy Tarnish?

Aluminum Alloy Tarnish

Have you ever noticed a grayish-green hue on aluminum alloy surfaces? That hue is called tarnishing, affecting many objects containing aluminum alloys. So, what is aluminum alloy tarnishing, and why does it happen? Let’s take a closer look at why this phenomenon occurs.

What Is Tarnishing?

Tarnishing is the chemical reaction between oxygen and certain metals, such as aluminum alloys, which form an oxide layer on the surface of these metals. This chemical reaction occurs when oxygen molecules in the air are attracted to the surface of the metal, causing oxidation. The thin layer on the metal’s surface is usually gray or green but can also be other colors depending on the alloy used.

Why Does Aluminum Alloy Tarnish?

Aluminum alloys are mixed with two or more metals to create a stronger material than each metal alone. While aluminum itself does not corrode easily, its alloys may contain other elements, such as copper, zinc, and magnesium, which are more prone to oxidation. When exposed to oxygen in the air, these elements can react with oxygen molecules and cause tarnishing over time. Additionally, because alloys generally have a lower melting point than pure aluminum, they are more vulnerable to damage from heat and humidity, which can also speed up this process.

How Can I Prevent Aluminum Alloy Tarnishing?

The best way to prevent tarnishing is by keeping your aluminum alloy items out of direct sunlight or areas with high humidity levels and temperatures above 70 degrees Fahrenheit (21 Celsius). Additionally, you can use a protective coating such as polyurethane paint or sealants to protect your items from oxidation. Finally, a regular cleaning with mild soap and water followed by drying with a soft cloth will help keep your items looking like new for longer periods.


Aluminum alloy tarnish is an unavoidable side effect of oxidation caused by exposure to oxygen in the air. Although it cannot be completely eliminated, there are steps you can take to slow down this process and keep your metal items looking like new for longer periods. Following these tips, you can enjoy your aluminum alloy items without worrying about tarnish ruining their appearance anytime soon!

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