A Guide to Anodized Aluminum Colors

Anodized aluminum can enhance the natural appearance of the base material or be modified to meet the user's desire while providing a wear-resistant and weather-protected surface. 

Through an electrochemical process, the natural oxide layer on aluminum is thickened, offering protection from wear and corrosion and enabling the metal to be dyed in a variety of colors. This process allows for a wide spectrum of colors by varying the thickness of the anodized layer and employing different dyeing techniques, making anodized aluminum a popular choice for diverse applications.

Beyond its visual appeal, the coloring of anodized aluminum adds functional value in industrial and aerospace settings where color coding is desired for functional or safety purposes.  It is also useful in electronic semiconductor applications when it needs to be apparent that a protective and non-conductive coating is present. Anodized aluminum's durability extends the product's lifespan by safeguarding both the material and color in abrasive and exterior environments. As a result, aluminum anodizing is a prevalent method across many industries, offering both protective properties and aesthetic appeal.

What is the Color Anodizing Process?

Color anodizing is a multi-step process that imbues aluminum with both aesthetic appeal and protective qualities. Here are the basic stages of this transformation:

Pre-Treatment

Before anodizing, the aluminum surface must undergo pre-treatment to ensure the quality of the anodized finish. The aluminum surface is cleaned and etched to remove impurities and create a consistent surface.  It is important to know that the surface finish you need must be achieved during these operations, as the anodic coating itself only builds on what you start with. 

So, if you want a rough finish, you must achieve that first before anodizing. If you want a bright, polished surface as a finished product, multiple operations may need to occur even before your anodized gets started.

Anodizing

The anodizing process creates a dye-absorbent porous oxide coating by immersing the prepared aluminum part in an electrolyte bath and applying an electric current.  The depth of color achieved largely depends on the depth of coating built and the type of coating chosen.  Sulfuric Anodize, or Type II, is usually the coating of choice.  Hardcoat, or Type III, has deeper pores with a thicker coating but is also a more dense coating and not recommended for brighter and vivid colors.

Coloring Techniques

A variety of techniques are employed to produce the desired hue:



• Dyeing: The immersion of the anodized part in a dye bath allows the porous oxide layer to absorb the dye. There are varying techniques to adjust the coloring operation to meet the target. Colors can range from very light to very dark. 
• Electrolytic Coloring: Also known as "two-step anodizing," electrolytic coloring involves introducing metal salts into the pores during the anodizing process, resulting in various colors, including bronze and black. This coating is typically used in outdoor and architectural applications.

Sealing

The sealing process entails moistening the oxide pores to seal them, keeping the color in place, and improving the anodized part's resilience to corrosion and longevity.  Several different seals are available, and the seal chosen should have the end use in mind to make the most of your anodized surface. 

Available Colors for Anodized Aluminum

Aluminum is the metal of choice for many applications, known for its ability to take on a variety of rich and vibrant colors and surface appearances. Anodized aluminum offers a spectrum of color choices, making it a versatile option for a myriad of applications where both appearance and performance are critical. 

Below is a list of some common colors available:

• Gold
• Blue
• Green
• Red
• Copper
• Black
• Gray
• Brown
• Purple
• Turquoise

At Light Metals Coloring, we can produce customized shades beyond these standard options. Most of the base colors have several different variations available, and by partnering with our dye manufacturer, we can formulate special dye makeups to come close to a non-standard color. 

It's important to note that even while some colors are standard, precise control over the anodization process allows for shade variances. Anodic Coloring is not as simple as going to the paint store for a color match, but by working with the right finishing partner, you can achieve and reproduce the desired result.

Common Applications for Coloring Anodized Aluminum

Colored anodized aluminum is widely used across various industries for its aesthetic appeal and functional benefits. Common applications include:

• Firearm components: Upper and lower receivers, Buffer assemblies, slip rings, charging handles, magazines, etc.
• Aerospace components: Commercial and military aircraft parts.
• Automotive components: Engine parts, brakes, and wheel spacers.
• Medical components: Medical devices, dental equipment, and surgical instruments.
• Marine components: Fishing equipment, boat hardware, covers, and hatches.
• Cosmetic components: Makeup packaging and fragrance bottles.

Color Anodizing at Light Metals Coloring

The world of anodized aluminum colors is vast and offers many possibilities for enhancing your products' appearance and functionality. At Light Metals Coloring, we take pride in our expertise in the color anodizing process, allowing us to provide a diverse range of vibrant and durable colors to meet your specific needs. Contact our metal finishing experts to learn more about how our color anodizing services can elevate your next project.