Considerations for anodized aluminum cladding

Declare LBC Red List Free products align with other requirements within the ILFI’s LBC and Core Green Building Certification and are recognized by the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) rating system, the International WELL Building Standard, and the U.S. Environmental Protection Agency’s (EPA’s) Recommendations of Specifications, Standards, and Ecolabels for Federal Purchasers. These requirements include ingredient disclosure thresholds, volatile organic compound (VOC) content and emissions, embodied carbon, and responsible sourcing.

A Declare Label as LBC Red List Free demonstrates full compliance with the highest level of LBC criteria. This means 100 percent of the product ingredients were disclosed to 100 ppm and confirmed they do not contain any Red List chemicals or applicable VOCs associated with the product. At least one finishing service provider has earned a Declare Label as LBC Red List Free for all its anodize finishes and colors.

Standard and specialty color range

Today, the consistent, matte finish produced by current, environmentally responsible anodize processes is preferred to the less consistent, higher gloss seen with the conventional, caustic etch process. The frosted matte appearance is more recognizable with darker colors and nearly imperceptible with lighter colors and clear anodize.

With quality control closely monitored by both computerized systems and experienced personnel, the finished material should fall within the acceptable color range. Anodize finishes meeting AAMA 611 will not differ in color by more than 5 Delta E. Some finishing providers deliver a narrower range of 1 to 3 Delta E. The range of variation usually is more detectable in lighter colors. Once installed, natural shading and lighting can also be perceived as tonal differences within a wall cladding system. To further minimize variation, one can disrupt side-by-side comparisons by using masonry or other materials to separate wall panels within a cladding system covering a large area.

The Mississippi Arts & Entertainment Experience, designed by LPK Architects, in association with Canizaro Cawthon Davis Architects and Gallagher & Associates, features copper anodize wall panels on the exterior and silver anodize wall panels on the interior.

Anodize color is determined during the electrolytic color process that immediately follows the anodization. The anodized aluminum is immersed in a bath containing an inorganic metal, such as tin, cobalt, or nickel. The metal deposits in the anodic pores by means of electrolytic current. This sometimes is referred to as a two-step color process. Different colors result depending on the type of metal and the length the aluminum soaks in the bath. Darker colors are created by extending the immersion time and increasing metal deposition.

Standard anodize color range from light to dark:

∞ Clear

∞ Champagne

∞ Light bronze

∞ Medium bronze

∞ Dark bronze

∞ Extra-dark bronze

∞ Black

To attract and retain high-tech tenants to California’s Mountain View Corporate Center, the owners invested in updating three buildings to a modern copper-colored metal panel facade. To achieve the intended appearance, more than 2100 m2 (23,000 sf) of aluminum panels were finished in copper anodize. The durable anodize also supports the property’s sustainability goals.. Photos courtesy Sheet Metal Systems Inc. and Linetec

Expanding the traditional color palette for anodize, specialty colors include copper and bordeaux. These are achieved with a third step where the anodize aluminum first is immersed in an electrically charged tin solution followed by a copper bath. While real copper is used, the anodize finish produced will not develop a green patina as it ages or leave run-off stains on adjacent building materials. Beyond color, anodized aluminum cladding offers visual enhancement and design flexibility. For example, post-finish treatments can mimic the look of a brushed, pre-aged, vintage quality.

Since the metal is easy to shape and cut, it can be fabricated into almost any geometric form with straight or curved edges. Panels intended as a shade, screen, or scrim can be perforated into punched patterns using circular, rectangular, or other shapes of various dimensions and spacing. For signage and artistic accents, the aluminum may be crafted freehand by a skillful tradesperson or with a computer-guided cutting machine.

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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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