IMF Goes Green


Anodizing (Type II)

Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts.  Anodizing increases the resistance of corrosion and wear
and provides a better adhesion for paint primers and glues as opposed to bare metal.  The anodic films can also be used for a number of cosmetic effects with thick porous coatings that can absorb dyes or with transparent coatings that can add interference affects to reflected light. 

Hard Anodizing (Type III)

Hard anodizing is a term used to describe the production of anodic coatings with film hardness or abrasion resistance as their primary characteristics. 

The coating thickness is greater than that of Type II sulfuric or Type I chromic acid anodize and is produced via special anodizing conditions (28-32 degree F solution, high current density, special electrolytes).

The coating differs from plating in that half of the coating penetrates the substrate and half builds up on the surface.  Typical hard anodized coating thickness range from 0.001" to 0.003", but varies depending alloy, specification or customer needs.

It is often used for engineering applications for components that require wear resistant surfaces such as pistons, cylinders, and hydraulic gears.  Hard anodized parts are often left unsealed to allow for maximum abrasion resistance, but can be sealed with a myriad of solutions to increase corrosion protection or lubricity.  

Chemical Film (Alodine)

"Alodine" is a non-anodic protective coating which is a microscopic thin film commonly prescribed on aluminum to: (1) Provide an excellent surface prep for paint (2) Aid in Corrosion Resistance (3) Impose desired Electrical 'Resistance' characteristics.

Electroless Nickel

Electroless Nickel is an auto-catalytic chemical technique used to deposit a layer of nickel-phosphorous or nickel-boron alloy on a solid workpiece.  The process relies on the presence of a reducing agent which reacts with the metal ions to deposit metal.  It provides excellent wear, abrasion, and corrosion resistance.

Due to it's ability to form a uniform coating, Electroless Nickel is an excellent choice for parts that are irregularly shaped or have deep recesses, cavities and pockets.


Passivation improves the corrosion resistance properties of components made of precipitation-hardened, austenitic, ferritic and martensitic steels.  Passivation treatments improve the surface condition of stainless steel by dissolving iron or other impurities that has been imbedded in the surface during forming or machining. 

If allowed to remain, the iron can corrode and give the appearance of rust spots on the stainless steel.

Passivation, which consists of immersing stainless steel componenets in a solution of nitric or citric acid without oxidizing salts, will dissolve the imbedded iron and restore the original corrosion-resistant surface by forming a thin, transparent oxide film. 

Precision Masking

Precision masking is the process by which specific areas of the part are protected or "masked" off.  Masking materials include liquid masking chemicals, plugs, plastic fasterners and tape or die cuts.  Typical features that may require masking are threaded holes, dowel pin holes, electrical contact points or areas, dissimilar metals on a single substrate and any tightly toleranced figure.


Polishing is the process of creating a smooth and shiny surface by rubbing it using a chemical action leaving the surface with a magnificent reflection.  In some materials, polishing is able to reduce diffuse reflection to minimal values.  When an unpolished surface is magnified thousands of times, it usually looks like mountains and valleys.  By repeated abrasion, those "mountains" are worn down until they are flat or just small "hills."  The process of polishing with abrasives starts with coarse abrasion and gradually increases with finer abrasion materials. 

Frequently Asked Questions:
What is anodizing?
          Anodize is the coating of aluminum oxide that is grown from the aluminum by passing an electrical current through an acid electrolyte bath in which the aluminum is immersed.  The coating thickness and surface characteristics are tightly controlled to meet and product specifications.  Aluminum oxide is an extremely hard material that approaches the hardness of a diamond.  As a result, the aluminum oxide layer provides excellent wear and corrosion protection.

What is the purpose of anodizing?
          General reasons for anodizing are: wear, resistance, corrosion resistance, surface lubricity, heat dissipation, dielectric (non-conductive) properties, adhesion and aesthetics.

Is anodizing environmentally friendly?
          Yes, anodize does not entail the use of heavy metals nor does it produce toxic waste.  Anodize meets the environmental and safety directives of the FDA, USDA, ELV, WEEE and RoHS. 

What substrates or base metals can be anodized?
          The three substrates that can be anodized are aluminum, titanium, and magnesium.  Steel or stainless steel cannot be anodized.

Are there any size limitations for my project?

          Yes, Please contact us for minimum and maximum sizes of materials that we can handle. 

Is there a price difference between conventional and hard anodize?
          Hard anodize is more expensive due to the increased energy requirements associated with the process.  Ending cost differences are dependent upon many variables in a given order.  For example: part size, racking instructions, packaging, etc.

What colors are available for anodize?

          A rainbow of colors are available.  Please ask and we can send a color palette which will allow you to match to your specifications or we can help you match to your project.

What alloys are best for anodizing?
          In general, wrought alloy series 1000-7000 provide the best corrosion and aesthetic properties that cast alloy.  Specific alloy choice to match performance needs should be discussed on a case-by-case basis.

How can I determine which process I should choose given the operating environment?

          So many variables come into play that in order to determine the optimal process we ask that you please contact one of our knowledgeable sales engineers or customer service reps for further help and clarification.  Indy Metal finishing offers testing solutions to identify the best process for given environments.

Do you take orders from clients outside the United States?
          Most definitely!  Pricing will be offered based upon payment in U.S. dollars via wire transfer in advance.