Aluminum Chromating
Aluminum Chromating is also known as Chemical Fillm or Chromate Conversion Coating, and is commonly referred to by trade names Alodine® or Iridite®. It protects aluminum from corrosion while preserving critical part dimensions, serving as an effective standalone finish or a reliable base for paint and other secondary coatings.
What Sets Us Apart
Our customers rely on us for our capacity and consistency. With the ability to accommodate parts up to 12 feet long, we routinely process large aluminum components like enclosures, frames, housings, heavy machined castings and large sheet metal fabrications.
Because we run this process daily, our chemistry remains stable and controlled. Our operators are experienced in handling large fabrications and complex assemblies, so parts move into processing quickly once they arrive. This helps us provide fast turnaround while maintaining a consistent, uniform appearance across orders.
Since we offer both electroplating and aluminum chromating in the same facility, you can send your steel and aluminum components to one place, simplifying logistics while servicing your customers faster.
Aluminum Chromating Finishes We Offer: Clear and Yellow
We provide aluminum chromating in both trivalent and hexavalent types depending on your application requirements.
Clear Chemical Film/Chromate
- Colorless Finish
- Trivalent / RoHS Compliant
- Provides a subtle protective layer for corrosion protectiom
- Commonly used in commercial and industrial applications
Yellow Chromate
- Distinct Yellow Appearance
- Hexavalent / Not RoHS Compliant
- Provides increased corrosion protection compared to trivalent chromate
- Commonly specified for aerospace and military applications
Appearance of Chemical Films
Both clear and yellow types produce a dull, uniform finish. Final appearance can vary greatly depending on alloy type and surface condition prior to processing. Visual variations do not affect coating performance.
We Understand Your Specifications: MIL-DTL-5541, ASTM B449 and More.
Manufacturer specifications can be confusing. Because we process finishes to a wide range of specifications daily, we understand what’s required and how it affects your parts. We’ll help you interpret the requirements so you can confidently choose a finish that meets both compliance and functional standards.
Two of the most common industry standards we process to daily include:
- MIL-DTL-5541
- ASTM B449
Our process is controlled and repeatable to ensure the finish consistently meets specification requirements.
Why Manufacturers Choose Aluminum Chromating
Aluminum chromating is used when parts need reliable and cost-effective corrosion protection that won’t affect critical dimensions.
Reliable Corrosion Protection
It’s primary purpose is to protect aluminum from corrosion and extend the life of the part.
Improved Aesthetics
Enhances the visual appeal of aluminum with a uniform finish.
No Measurable Buildup
Does not add significant thickness to the surface, preserving critical part dimensions.
Electrical Conductivity
Since it has low electrical contact resistance, it can be a good choice for applications requiring efficient conductivity.
Enhanced Adhesion
Provides an excellent base for subsequent coatings such as paint, powder coating and adhesives, ensuring a durable finish.
How the Chromate Conversion Coating Process Works
Aluminum Chromating is a chemical finishing process that immerses aluminum parts in a controlled solution, activating a reaction that converts the surface into a protective chromate layer. Unlike plating, which adds material on top of the part, this type of finishing becomes part of the aluminum itself.
The Aluminum Chromating Process Includes Three Main Steps:
- Cleaning and Surface Preparation
Parts are cleaned and lightly etched to remove oils, oxidation, and contaminants. This prepares the aluminum surface so the coating can form evenly and perform as intended. - Chemical Conversion
Parts are immersed in a chromate solution, where a controlled chemical reaction converts the outer surface into a protective chromate layer. - Rinsing and Drying
Lastly, parts are rinsed to remove residual solution and dried thoroughly to prevent bleed-out.
Since aluminum surfaces can scratch or scuff easily, we offer protective wrapping when parts may contact each other during handling or shipment. Wrapping is typically provided, with the need determined based on part type and shipping requirements. If wrapping is required for your parts, we recommend noting it on your purchase order.
Aluminum Chromating and Chemical Film FAQ’s
There is no functional difference. These are all interchangeable terms referring to the same finishing process.
Aluminum chromating chemically converts the surface of aluminum to improve corrosion resistance, while plating adds a separate layer of metal onto the surface.
Because chromate conversion coating becomes part of the aluminum, it preserves critical dimensions. Plating adds measurable thickness, which can affect part fit and tolerances.
No. Aluminum Chromating creates an extremely thin layer which does not add measurable thickness to aluminum parts.
Alodine® and Iridite® are branded chemical conversion coatings used to protect aluminum. Despite being from different manufacturers, both coatings meet the specification requirements for MIL-DTL-5541.
Gatto’s chemical film process is also capable of meeting these specifications, providing an effective and reliable alternative.
Located in Chicago, we reach 65% of the U.S. in a day, lowering freight costs, reducing lead times, and enabling direct shipping to your customer.
With 210,000 sq. ft., we process full truckload orders efficiently, keeping parts organized and on schedule with dedicated staging, processing, and tracking.
Flaking, bleed-out, poor adhesion, we catch plating issues early before they turn into costly problems.
From fast quotes to clear answers, we simplify the plating process so you can focus on the rest of your project.
Contact Our Plating Experts
Whether you know exactly what you need or just need to talk it through, we’re here to help with quick turnaround times and expert guidance.