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LNL Anodizing - Frequently Asked Questions

  1. What Is Anodizing?
  2. What is the purpose of anodizing?
  3. How is Price Determined?
  4. How to Prepare to Anodize Aluminum Parts?
  5. Will Anodizing Cause Loss of Design Detail?
  6. Is Anodizing Safe?
  7. Does your anodizing and coatings cover dings or scratches on parts?
  8. How do you protect areas of the part we dont want anodized?
  9. Is there Dimensional Growth During Anodizing?

#1) What Is Anodizing? - Anodizing is "a process to coat a metallic surface electrolytically with a protective or decorative oxide." The anodic coating consists of hydrated aluminum oxide and is considered resistant to corrosion and abrasion. Coatings are 0.1 to 1.0 mil thick and are essentially transparent, although they may be colored.

Unlike most other finishes, anodizing preserves the natural luster, texture, and beauty of the metal itself. The anodized coating is hard, durable, will never peel, and, under normal conditions, will never wear through.

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#2) What is the purpose of anodizing? - The purpose of anodizing is to form a layer of aluminum oxide that will protect the aluminum beneath it. The aluminum oxide layer has much higher corrosion and abrasion resistance than aluminum. There are some types of anodizing that produce a porous oxide layer that can be colored with organic dyes or metallic pigments giving the aluminum a decorative and protective finish. In short, the main purposes for anodizing are corrosion resistance, abrasive / wear resistance and cosmetics.

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#3) How is Price Determined? - Price Determined by End Use, Alloy, Temper, Finish, Material Source, Fabrication, Coating Thickness Tolerances, Color, Dimensions, Metal Volume, Special Handling etc.  Projects pricing is based on a number of variable factors. A pricing inquiry checklist for accurate quotes would include:

  • End use of product
  • Alloy, temper, and finish desired
  • Fabrication work needed
  • The finished appearance (etched or brightened)
  • Anodize coating thickness
  • Color desired
  • Metal dimensions (thickness, width)
  • Metal volume required
  • Required tolerances for camber, squareness, length, and width
  • Pick & Pack Services including custom, market-ready packaging
  • Special handling, packaging or protective shipping requirements
  • Warehousing / storage required
  • Transportation / Logistics shipping from / to your location based on your schedule requirements
  • Prices are offered per pound, per load or per square foot of material, depending on the type of project. For more detailed information, submit an var now = new Date();document.write(now.getFullYear())/request_quote.htm">online project quote request. One of Superior's project specialists will respond and provide more details as quickly as possible.

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#4) How to Prepare to Anodize Aluminum Parts? - Preparations: 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:

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

Decide what pretreatment, if any, you want:

  • etch (matte)
  • clear anodize (satin)

Specify whether you want the metal left clear or colored:
If colored, provide a sample of the color you want.

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.

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.

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. 

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#5) Will Anodizing Cause Loss of Design Detail?  Detail Loss?: Ornamental Metal Industry, Intricate Designs. Anodic Coatings, Complex / Delicate Scrollwork, Etching Design.  In the ornamental metal industry, where projects sometimes include intricate designs, there is sometimes a concern that detail will be lost with a protective or decorative coating application. Superior Metal Technologies has the solution to address your concern.

Generally, thin anodic coatings, with thicknesses as small as .05/mil, will cause no discernable loss of detail to an etched design. You might lose a little detail if you are talking about something with complex and/or delicate scrollwork.

Please contact one of our highly experienced anodizing specialists if you have any concerns about detail loss. LNL Anodizing has the expertise to create beautiful anodized coating while maintaining the integrity of an intricate design. We can help make your vision a reality.

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#6) Is Anodizing Safe?:  Environmentally Friendly Technology, No Harmful or Dangerous By-Products, Non-Toxic Finish, Heat Resistant, Recycled By-Products, Safe Work Environment.  The unique anodized finish of Superior's comprehensive range of aluminum anodizing services is only one of the properties that make it a desirable finishing process. Anodizing is the perfect solution when health and environmental concerns arise.

When it comes to coatings, anodizing is a safe and environmentally friendly technology, as clean a process as is available today. Anodizing is an acceleration of a natural oxidation process. It does not produce harmful or dangerous by-products, and will not damage human health or the environment. Other benefits include:

  • An anodized finish will not break down or decompose
  • The finish is non-toxic
  • It is heat-resistant to 1,221 f, (the melting point of aluminum)
  • Anodizing uses simple water-based chemicals that can be treated easily and that release no harmful by-products
  • The liquid by-products are recycled and returned to the process
  • Solid by-products can be separated for other uses, such as:
    • Aluminum manufacturing
    • Baking powder
      Cosmetics
    • Newsprint
    • Fertilizer

Anodizing's primary by-products are harmless aluminum hydroxide and aluminum sulfate can be used as filters in the sewage treatment process of municipal sewage treatment plants.   Anodizing plants are safe, well ventilated, worker-friendly environments. Workers are well trained in the use of anodic materials and processes. In general, to ensure worker safety employees only need to wear a minimum of special protective clothing. In most cases, only a minimum of safety equipment is required.

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#7) Does your anodizing and coatings cover dings or scratches on parts? - Good question. It sure would be nice to have a magic coating! If you are familiar with auto body or painting, you know that all imperfections on the metal must be filled or sanded prior to painting. The same rule applies to metal finishing. Any imperfection on the metal (dents or deep scratches) must be corrected prior to anodizing or coating.

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#8) How do you protect areas of the part we dont want anodized?: - Masking. LNL ANODIZING uses precision masking for the areas you dont want anodized.

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#9) Is there Dimensional Growth During Anodizing?   - As previously mentioned in question #5, anodizing is the process of electrochemically converting the surface of an aluminum part to aluminum oxide. Aluminum oxide occupies about two times the volume as that of raw aluminum. Therefore anodizing will cause parts to grow dimensionally. This factor should be taken into consideration when designing parts that will be anodized.

Typical standard clear and color anodizing creates an aluminum oxide film in the range of .0002 to .0008 inches, (.005 to .020 mm), on each surface. Hard anodizing is typically in the range of .0005 to .003 inches, (.013 to .076 mm), the most common being .002 inches. (.051 mm).

The process of hard anodizing a part to .002 in. film thickness will therefore grow .001 in. on each surface or .002 in. in overall dimension.