With extensive expertise in metallurgical engineering and surface science, Dr. Judy Runge brings proven experience in anodising, materials characterisation, failure analysis (FMEA), and aluminium surface treatment. Her strong background in product development, continuous improvement, and innovation supports industries in advancing manufacturing processes and enhancing material performance.

In an interview for “American Aluminium Industry: The Path Forward” e-Magazine, Judy emphasised the need for stronger collaboration between alloy producers, designers and finishers, noting that anodising is often treated as a surface coating rather than a structural growth tied to alloy quality. By integrating finishing considerations early in product design, industries can avoid performance gaps and unlock greater engineering value.

Runge also calls for greater education and awareness across the value chain, pointing out that many engineers still overlook the influence of alloy microstructure on anodising results. With advanced rectifier technologies, safer chemistries, and recycling-focused practices, anodising is evolving into a leading green finishing process that can meet modern performance and sustainability standards.

AL Circle: As a long-time contributor to the Aluminum Anodizers Council, how have you seen industry standards and anodising practices evolve across the Americas in the past two decades? 

Judy Runge: Anodic Coatings for Aluminium and Aluminium Alloys, MIL A 8625, was first published in 1953 and was most recently revised to MIL-PRF-8625, effective November 23, 2020. The specification is well reviewed and determined to be valid and is, in fact, the most frequently referred to in the US by Job Shop Anodizers. Although the basic processing and general performance requirements of the anodic oxide have remained the same over the years, testing and sampling methodologies are updated to reflect more modern practices. So, we’re seeing that the main process specification for the anodising process in the US is more than 70 years old! 

This says a lot about the anodising industry – and how the oxide is thought about and implemented in general. So much analysis of Anodic Aluminum Oxide has taken place over the last 70 years that we know a lot more about how the oxide nucleates and grows on aluminum and its alloys, which changes our explanations for why and how this marvelous highly-ordered, uniform and continuous, nanoscale structure of individual columns, each with a rounded bottom and a central pore, forms and functions. 

While it is a good process foundation, MIL A 8625 doesn’t reflect the changes in environmental requirements and need for process efficiency that have been addressed worldwide by chemical and equipment suppliers who see to it that chemistry is safe and easy to use, while improving process recyclability and minimizing waste and waste treatment methods to make anodizing a leading green process for aluminum metal finishing. The technology of the various power supplies and rectifiers has advanced to easily enable the implementation of ramp and pulse technologies such that thick oxides of the highest quality can be grown on even the most complex alloys to serve corrosion resistance and dielectric applications that anodic oxides in the past have never been able to meet!

AL Circle: What role does the Aluminium Anodizers Council play in driving more dialogue between smelters, casthouses, and surface finishers to ensure that recycled content does not come at the cost of anodising performance?

Judy Runge: The AAC is an educational resource for the anodising industry. Our educational program efforts that culminate in our Annual Fall Conference, Technical Bulletins, Webinars and Podcasts have included the leaders in aluminium alloy and recycling process development, such as Hydro, Rio Tinto and Novelis. We look to make connections between the anodizer and the primary source for the aluminium alloys that comprise the anodes, because we have to face it – component designers often look first to fulfil mechanical requirements before they look to the finish. We target our educational programs to anodizers, designers and end-users to select the anodic oxide as the finish of choice and help develop strategies that yield the desired appearance and engineering performance of the total product, including the anodic oxide.

AL Circle: Which alloy-specific challenges are most commonly overlooked when it comes to anodising, particularly in North American production lines? Are these quality concerns design-related or process-driven? 

Judy Runge: There is a rule of thumb: the more complex the alloy, the more difficult it is to anodise. Aluminium alloys are usually designed with specific mechanical properties in mind, and seldom with how the metal should be finished. I believe that many designers think of the anodic oxide as a deposit similar to an electroplated finish or something to be applied like a lacquer or a paint, which covers the component surface rather than develops it. However, the beauty of the anodic oxide that showcases the metal quality is often a part of engineering designs. Although that appearance is desired, if a more complex alloy is specified at the beginning, yielding an appearance after anodising that is disappointing, the blame is often on the anodizer, not the designer. I believe that if component industrial designers would incorporate metal finishing as an important detail in their initial designs, as a mechanical property, and involve their metal finishers in the design discussion, these challenges could be minimised, and even overcome. This design perspective is global, not only isolated to North America. 

Nevertheless, anodizers who still operate their anodising lines like they did 20 or more years ago will have problems managing finish requirements for today’s components that may utilise different alloys for the same or similar designs. For example, lithiumbearing alloys anodise differently from common 2XXX series or 7XXX series alloys, and they are becoming more common in components for the Aerospace and Aircraft Industry. Being aware of the ramifications of alloy chemistry, composition, deformation, and thermal history is more important than ever when tuning an anodising process for successful uniform and continuous oxide growth.

To explore the full interview and gain deeper insights into the aluminium anodizing, click here.