FAQ: How to Prepare to Anodize Aluminum Parts?

Prepare to Anodize Aluminum Parts: Anodizing Finish, Pre-Treatment, Clear / Color Coating, Store Aluminum Properly, Aluminum Alloy, Fabrication, Low Heat Welding, Dyeing / Coloring

When preparing to anodize aluminum parts, consider that architectural and other structural items usually call for an "Architectural Type I" or "Architectural Type II" anodized finish. Exterior items need a Type I (minimum .7 mil thickness) and interior items should have a Type II (minimum .4 mil thickness) finish. Coating selection should be based on the end-use of the piece, and the properties required of it.

Step-by-Step: Prepare to Anodize Aluminum Parts

Each anodic coating has unique properties that makes selecting the best choice for your particular needs your first decision. Once a coating is selected, there are a number of steps you'll need to be aware of before the actual anodizing process is done.

These are the steps to take in order to help you customize the correct anodizing process, and obtain the high quality finished product you need: 

1. Determine the proper anodizing finish to use

   This is determined by the final use of the piece, and the physical specifications and characteristics needed, such as:

   • color
   • hardness
   • indoor or outdoor use
   • resistance to high UV levels and fading
   • resistance to corrosion

2. Decide what pretreatment, if any, you want:

   • etch (matte)
   • clear anodize (satin).

3. Specify whether you want the metal left clear or colored

   If colored, provide a sample of the color you want.

4. Select the appropriate dyeing (coloring) process

Specify hot water seal only, if your metal is going to be welded or heated after anodizing, to help prevent discoloration around the welding sites.

• Integral color is available. The bronze colors produced are generally stable and suitable for architectural applications.
• Two-step color also produces stable bronzes ranging from light champagne to jet black. It, too, is considered suitable for architectural applications and is a newer technology than integral color.
• Dyes for almost any color are available; however, the dyes vary in their degree of colorfastness. The exact color you want may not be available in a dye suitable for, say, outdoor exposure to bright sunlight.

5. Prepare your job

   Proper handling and care is important if you want to get consistent results. When ordering materials and fabricating your job, please keep the following in mind:
   • Store all aluminum in a manner that prevents metal-to-metal contact when moisture is present, whether it is to be anodized or not. Contact can result in "water etch." While minor water etch can sometimes be removed, severe water etch will ruin your metal.
   • Choose the right alloy. Some alloys and tempers respond better than others to pretreatment and anodizing. You should always use the same alloy throughout any one job. Variations can lead to color differences after anodizing.  Our consultants can advice you as to the proper alloy for your specific application.
   • Have all fabrication work (cutting, welding, bending, grinding, buffing, etc.) completed before anodizing. You will not want to disturb the anodized coating on a fabrication.

   • Superior offers facilities for minor fabrication services:
   • Welding
   • Cutting to size
   • Hole punching and drilling into extrusion pieces.

   We can also provide drilling and tapping of holes or other operations, after anodizing is completed, when exact dimensions are critical.

   • When performing welding operations, use the lowest heat possible for optimal performance. Excessive heat from welding can affect the properties of nearby metal and lead to irregular discoloration after anodizing.

   • Use the proper alloy welding wire, to prevent your weld from becoming charcoal gray or black after anodizing. Your welding supplier can recommend the right wire.

   • Avoid using paints, varnishes, etc. on surfaces to be anodized.
   • Avoid applying adhesive tapes – they often leave glue residues. We use water-based cleaners that are effective on fabrication oils and buffing compounds but not on materials that require solvents.
   • Once fabrication is complete, schedule anodizing as soon as possible. Aluminum is an active metal and, when unprotected, is subject to damage from fumes, mists, and even oily fingerprints. The longer it sits out the more pronounced the damage can be.

While the aluminum anodizing process will clean up your metal a bit, it will only do so much. However, an "etch" pre-treatment will minimize, and even remove, much surface "noise," such as small nicks, scratches, and die lines.

Superior's highly trained "anodizing specialists" can help you make the process fast, easy and stress-free. Our 60 plus years of experience in the Coatings Industry make us the right choice for your all your anodizing needs.