Considerations for anodized aluminum cladding

Most finishing service providers and metal cladding manufacturers recommend any cuts, welds, or shaping are completed before the anodize process. With cut material, this ensures the inside edge also is finished. If welding is necessary, specify 5356 wire and the lowest possible heat is used to prevent halo discoloration in the anodized material.

Due to the extreme hardness of anodic coatings, it also is recommended all forming and bending be done prior to anodizing. Most post-production bending can cause anodize to “craze,” which produces a series of small cracks in the finish creating an undesirable, web-like appearance. One should consult with the finishing service provider to ensure the best appearance, the highest performance, and a fully warrantied finish.

Basic care and maintenance

Most finishing providers offer up to a 10-year extended warranty for anodized aluminum, but its lifespan can last decades with routine maintenance.

The hardness and durability of anodize upholds its appearance and performance. Anodize is a factory-controlled finishing process; therefore, it cannot be touched-up like a painted surface because anodize is integral to the metal.

Even with its resiliency, anodize aluminum’s natural aesthetic still may be marred by harsh chemicals and neglect. Some conditions may only affect the surface finish and not reduce the service life of the aluminum, but mortar, cement, and other alkaline materials can corrode an anodize finish if they are allowed to dry on the metal’s surface. If reasonable care is taken during handling, and high and low pH chemicals can be avoided, the anodize finish will remain in good repair.

If an aluminum panel suffers a severe scratch or gouge, a paint that resembles the anodize color may be used for small areas. An experienced field service finishing professional would pretreat the damaged area with a chromate conversation coating and then carefully touch up only the visible, raw aluminum. The painted surface will look different than the anodized material, but properly applied, the metal will have more protection than if it remained exposed.

As an alternative to paint touch-up or for anodized wall cladding with more extensive damage, building owners and facility managers may choose to replace or overclad the panel(s) with new, anodized aluminum. If the repair or replacement was not manufactured and finished at the same time as the original, there will be some variation; but it will provide a similar look and specified requirements.

Contributing to maintaining anodized cladding’s optimized aesthetic and performance, finishing service providers and cladding manufacturers can provide specifications professionals with cleaning and care instructions. As examples, strong acid or alkali cleaners and abrasive cleaning pads, should not be used and may affect the finish warranty.

While it is a hard and hearty finish, the best advice is to be gentle. A clean water rinse using moderate pressure will help remove most dust and dirt from anodized aluminum with minimal impact to the surrounding environment, further supporting the project’s sustainability and longevity.

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3 comments on “Considerations for anodized aluminum cladding”

    1. are you looking for presentations on anodizing for exterior walls, or for a particular panel system?

  1. I’ll start by saying that Linetec is a great company that willingly offers expert advice, and provides finishing services second to none. I thank Linetec (particularly Tammy Schroeder) for the many valuable articles it has provided, and for the wealth of information on its website.

    But I’ve always been puzzled by Linetec’s use of terms related to anodizing. When talking with their representatives, I often would suggest changes, but they never responded. Of course, the people who deal with clients usually can’t make changes on their own, so in June of 2010, I sent an email the vice president of sales and marketing. In it, I explained that “Anodize is a verb, it is not a noun. To anodize is to apply a protective coating. Anodizing is either a verb, ‘We are anodizing the metal’ or a gerund that is the name of the process, ‘Let’s talk about anodizing.'” I also noted other instances where Linetec’s literature or website used terms incorrectly. I don’t recall receiving a response.

    More recently, while serving on the Construction Specifier’s Editorial Advisory Board, I reviewed an article titled “Maintaining and Protecting Architectural Aluminum Finishes,” which appeared in the February 2010 issue of the Construction Specifier. In my comments, I changed “anodize” to “anodizing” in several locations, and to “anodized” in at least one location. It was interesting to see that in the published article, virtually all of my other suggestions and comments were addressed, yet the incorrect use of “anodize” remained.

    If this were an industry trend, I might care less, but I’ve looked at information about anodizing published by several other anodizing companies, and they use the terms correctly – even the oddly-named “US Anodize.”

    I know, some will say, “What’s the big deal? It’s only a word!” But in the world of specifications and construction documents, we must be consistent, and we must use defined words as they are defined. I don’t know why Linetec insists on its use of these words in their unusual way, but at least they are consistent. I can imagine a time when someone new to the company was familiar with the word “paint” – which can be either a noun or a verb – but not “anodize” – and might have thought “anodize” would be used in the same way as “paint.” I doubt that specifiers have been using “anodize” as a noun; I wonder how many cringe just a bit when they see it used that way.

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