Shared Learnings: What is Anodizing? (Part 2 of 2)

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

Specifying Anodized Finishes

The Aluminum Association has developed a system of designation for anodized finishes on aluminum. Specific finishes of the various types are designated by a letter followed by a two-digit numeral. Each designation may be combined into a single composite designation to identify a sequence of operations covering all of the important steps leading to a final complex finish.

 

Almost all finishes used on aluminum may be subdivided into three major categories: mechanical finishes, chemical finishes and coatings.

Descriptions of the most commonly utilized finishes are as follows:

* Mechanical: (M)
M10 – Unspecified as fabricated

* Chemical (C)
C21- Fine matte (eco-friendly etch process)
C22 – Medium matte etch (caustic etch process)

* Anodic Coatings (A)
Architectural Class II (0.4-0.7 mils thick)
A31 – Clear
A32 – Integral Color
A34 – Electrolytically deposited color (two-step)

Architectural Class I (0.7 mil and thicker anodic coating)
A41 – Clear
A44 – Electrolytically deposited color (two-step)

All composite designations are preceded by the letters “AA” to identify them as an Aluminum Association designation.

* Example 1: Aluminum Association (plus) Mechanical Finish (plus) Chemical Etching (plus) Anodic Coating translates to:
Class II Clear Anodized Finish AA‑M10‑C21‑A31 complying with AAMA 611

* Example 2: An Architectural Class I medium bronze electrolytic deposition (two-step) would be designated:
Class I Color Anodized Finish: AA‑M10‑C21‑A44 complying with AAMA 611. Provide color as indicated.

 

Maintenance and Cleaning

As with any finished building material, anodized aluminum requires reasonable care prior to and during installation, and periodic cleaning and maintenance after installation. Although anodized aluminum possesses exceptional resistance to corrosion, discoloration and wear, its natural beauty can be marred by harsh chemicals, rough conditions or neglect. The marks resulting from such mistreatment may be permanent. For example, mortar, cement and other alkaline materials will quickly corrode anodic coatings if allowed to dry on the metal surface.

Surfaces exposed to the atmosphere will collect soil and dirt, the amount of which varies depending on geographic area, environmental conditions, finish and location of the building. More frequent cleaning may be required in heavily industrialized areas compared to rural areas. Seasonal rainfall can reduce washing frequency by removing water-soluble deposits and less adherent soil. In climates where rainfall is low, atmospheric washing of the surface is minimal. These areas may require more frequent cleaning than in areas where rainfall is more prevalent.

Never use aggressive alkaline or acid cleaners on aluminum finishes. Do not use cleaners containing trisodium phosphate, phosphoric acid, hydrochloric acid or similar compounds. It is preferable to clean the metal when shaded. Do not attempt to clean hot, sun-heated surfaces since chemical reactions on hot metal surfaces will be accelerated and non-uniform.

**

Resources:

* Aluminum Anodizers Council
* The Aluminum Association
* American Architectural Manufacturers Association
* Linetec
* Tubelite Inc.

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]

Shared Learnings: What is Anodizing? (Part 1 of 2)

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

What is Anodizing?

Anodizing is an electrochemical process that converts aluminum’s metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. It is readily available for storefront, curtainwall, entrances and daylight control systems.

Exposed to the earth’s atmosphere, aluminum combines with oxygen to form a protective surface film, which inhibits further oxidation of the aluminum. This natural oxide is extremely thin, loosely adhered to the aluminum surface and easily removed by handling. Anodizing is a process, which thickens the natural oxide film resulting in a heavy aluminum oxide film of controlled thickness having the hardness similar to that of a ruby or sapphire. Anodizing is, therefore, a matter of highly controlled oxidation—the enhancement of a naturally occurring phenomenon.

Anodizing uses the base metal – the aluminum alloy – to create a thin, extremely strong and corrosion-resistant finish. The anodized surface is very hard and thus preserves and extends the life of the aluminum product. Architectural aluminum anodic coatings provide good stability to ultraviolet (UV) rays and does not chip or peel.

The anodic oxide structure originates from the aluminum substrate and is composed entirely of aluminum oxide. This aluminum oxide is not applied to the surface like paint or plating, but is fully integrated with the underlying aluminum substrate, so it cannot chip or peel. It has a highly ordered, porous structure that allows for secondary processes such as coloring and sealing.

 

Anodizing offers a range of colors in earth tones, such as champagne, bronze-tones and black. Unlike other finishes, anodizing allows the aluminum to maintain its metallic appearance. Clear anodizing does not incorporate any pigments.

When aluminum is anodized, an electrical current is passed through a bath of sulfuric acid (the electrolyte), while the aluminum being treated serves as the anode. This produces a clear film of aluminum oxide on the aluminum’s surface. This layer is mostly porous with a very thin barrier layer at the base. This structure lends itself very well to electrolytic coloring.

Anodizing is a water-based process and uses no volatile organic compounds (VOCs). There are no vehicle solvents, no carrier resins, and any pigmentation used in anodizing is created by extremely small amounts of metals or dye securely locked within the hard surface. No toxic organics are used in anodizing. Recyclability of aluminum is unaltered by anodizing and no intermediate processing is needed for anodized metal to re-enter the recycle chain.

Anodizing is a safe process that is not harmful to human health. An anodized finish is chemically stable, will not decompose and is non-toxic. The anodizing process is non-hazardous and produces no harmful or dangerous by-products. Under U.S. Environmental Protection Agency (EPA) rules, conventional anodizing generates no hazardous waste; it does not use VOCs or EPA-listed toxic organics.

Anodized products have an extremely long life span and offer significant economic advantages through maintenance and operating savings. Anodizing is a reacted finish that is integrated with the underlying aluminum for total bonding and unmatched adhesion.

The Anodizing Process

* Clean – The anodize process begins with the material being cleaned in a non-etching alkaline chemical cleaner to remove all shop dirt, water, soluble oils and other unwanted surface contaminates. which may have accumulated on the material during handling and/or manufacturing.

* Rinse – After cleaning, the material is rinsed and is then ready for etching.

* Etch – Etching is an important step during the anodize process. It is designed to dissolve a thin layer on the surface of the aluminum to develop a smooth uniform finish. Most anodizers have changed their etch chemistry from conventional caustic etch to a more eco-friendly acid etch technology.

The eco-friendly acid etch creates an aesthetically appealing, “frostier” appearance that helps hide small defects, such as die lines, flow lines, minor corrosion and scratches, that may occur on the aluminum surface. Although neither conventional or acid etch removes irregularities in the aluminum, acid etch does a better job of concealing them. This gives the material a better aesthetic finish on both primary and recycled aluminum extrusions.

* Desmut – Material is then moved to deoxidzing and desmutting process, which further prepares the aluminum surface for subsequent finishing. This step removes surface oxides. It also removes smut, which is a combination of intermetallics, metal and metal oxides remaining on the surface after cleaning and etching. And, it actives the surface for the electrochemical anodizing.

* Anodize – In the anodizing tank, the electrochemical oxidation of an aluminum surface takes place to produce a stable film of oxide. In this process, a porous, insulative layer composed of aluminum and oxygen is produced by passing electricity through the aluminum in a conductive medium. The basic structure of an anodic coating is based on a series of hexagonal columns of oxide, each with a central pore and a thin barrier layer separating the electrolyte in the base of the pores from the underlying metal.

* Electrolytic Color – The coloring of an anodic film is designed to enhance the appearance of the material and broaden the opportunity for anodized aluminum applications. In electrolytic coloring, or “two-step” coloring, anodizing is followed by the electro-deposition of a metal. AC power is used to deposit tin metal. Deposition takes place at the bottom of the pore. The intensity of the color is dependent on the amount of tin deposited and the packing density.

* Seal – After anodizing and coloring, the material is sealed in a mid-temperature hydrothermal seal and then given a final hot water rinse. This last, important step ensures that the high-quality anodized finishes will maintain their beauty and durability for many years.

 

**

Resources:

* Aluminum Anodizers Council
* The Aluminum Association
* American Architectural Manufacturers Association
* Linetec
* Tubelite Inc.

Watch for part 2 on anodizing in March and in “Architect’s Guide to Glass and Metal.”

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]

The Benefits of Natural Daylighting – Part 3 of 3

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

Daylighting and Retail

Recent studies report that daylighting can offer retail establishments a strong competitive advantage. This is supported by a study commissioned by PG&E that compares the retail sales performance of 108 stores operated by a large (unidentified) chain retailer. Two-thirds of the stores had skylighting, and the remaining one-third did not. Otherwise, the stores were very similar, with the same basic interior design, the same merchandise and all management and advertising handled by headquarters. Considering several factors, skylighting was found to have the largest impact, boosting a store’s sales index by an average of 40%.

The appearance of daylighting very often contributed to achieving a fresh appearance: clean, crisp, clear and bright. One effective application of daylight is incorporating skylights in the changing room to provide an opportunity for consumers to see natural skin tones, and fabric colors as they will be experienced outside of the store.

Walmart in Aurora, Colo., uses vertical clerestories to effective daylight the store. Photos courtesy of DOE/NREL, Credit – Pat Corkery.

Walmart in Aurora, Colo., uses vertical clerestories to effective daylight the store. Photos courtesy of DOE/NREL, Credit – Pat Corkery.

Wal-Mart Success Story

Many Wal-Mart stores and distribution centers around the world include a daylight harvesting system, which integrates skylights that dim or turn off interior electric lighting in response to the amount of daylight available. By using dimmable T-8 fluorescent lamps, electronic continuous dimming ballasts and computer controlled daylight sensors with approximately one skylight per every 1,000 square feet, they take full advantage of natural light when available.

Daylight harvesting is estimated to save up to 75% of the electric lighting energy used in the sales area of a supercenter during daylight hours. Each daylight harvesting system is estimated to save an average of 800,000 kWh per year, which is enough energy to power 73 single-family homes (11,020 kWh average annual usage) for an entire year.

Every facility Wal-Mart builds today from the ground up includes a skylight/dimming system. Nationwide, Wal-Mart builds or converts 200-300 facilities each year. All new stores will include the daylighting system.

NREL has been monitoring and evaluating more than 50 different technologies that Wal-Mart installed in its experimental Supercenter store in Aurora, Colorado, including daylighting. Photos courtesy of DOE/NREL, Credit – Pat Corkery

NREL has been monitoring and evaluating more than 50 different technologies that Wal-Mart installed in its experimental Supercenter store in Aurora, Colorado, including daylighting. Photos courtesy of DOE/NREL, Credit – Pat Corkery

**

Resources:

* Tubelite Inc.
* Retail Skylighting (PDF)
* Architects’ Perception of Daylighting in Commercial Building Design
* Daylighting Collaborative
* Energy Design Resources
* Concepts for Daylight Harvesting (PDF)

...[View full article]

The Benefits of Natural Daylighting – Part 2 of 3

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

An integrated design balances the cooling load of the window against required daylight illumination levels, thereby capturing both cooling and lighting energy savings without creating discomfort. A poor design imposes a substantial cooling load and creates glare. Achieving this balance requires careful and informed design and engineering.

Daylighting requires the participation and cooperation of multiple disciplines — architecture, lighting design and mechanical system design in conjunction with proper glass selection. Even when the proper components are selected, poor design and commissioning practices often lead to unreliable performance and uncomfortable work environments.

Control the Glare

Glare from natural sunlight can offset any positive attributes of daylighting. Glare will contribute to eyestrain and reduced productivity. Care must be taken in how daylight is allowed into the building without causing glare.

Some design elements may include:

* Exterior sunshades – Effective on south facing elevations only and may not have a positive effect during the winter months when the sun is low in the sky

Tubelite Inc. – Max/Block™ Sun Shade

* Translucent (as opposed to transparent) glazing – Very effective when used in skylighting applications

* Light redirecting systems – Light louvers or light shelves are effective at both controlling the glare as well as redirecting light toward the ceiling.

LightLouver LLC

* Manually or automatically controlled blinds – Consider blinds between the glass to avoid damage and eliminate cleaning

Wausau Window and Wall Systems – projected window with integral blinds

* Electrochromic or thermochromic glazing – Tints the glass either electronically or by natural solar heat.

SAGE Electrochromics

**

Resources:

* Tubelite Inc.
* Light Louver LLC
* Wausau Window and Wall Systems
* SAGE Electrochromics
* Daylighting Collaborative

Watch for part three and three on daylighting in January and in “Architect’s Guide to Glass and Metal.”

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]

The Benefits of Natural Daylighting – Part 1 of 3

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

mattophoto architectural photographyAs winter approaches, and the amount of daylight decreases, it’s important to realize the positive effects of natural daylight. The lack of daylight has been documented to cause Seasonal Affective Disorder (SAD), maladjustment of our body clocks (circadian rhythms) and consistent periods of reduced productivity and enthusiasm. One solution is providing a well-lit space, with as much natural light as possible. Daylighting provides superior quality, full-spectrum, flicker-free light that positively impacts behavior. In study after study, daylighting is correlated to dramatic improvements in human performance in retail, workplace, educational and health care facilities.

Daylight is a full spectrum source of visible light. That is, it imparts the same spectral distribution as sunlight. Unlike electric lights, which sometimes provide a limited spectral range that is concentrated in the blue/green or yellow/green range, daylight is best suited to human vision. Daylight can also provide various illumination levels through proper design. These inherent characteristics of daylight contribute to improved lighting quality by enhancing color discrimination and rendering. Working by daylight is believed to result in less stress and discomfort.

Turn Off the Lightsmattophoto architectural photography

Daylighting saves dollars by using controls to automatically turn off the electric lights when interior daylight levels are sufficient for the task. This reduces both lighting and cooling costs, since reduced electric lighting cuts cooling loads. Daylight is inherently more efficient than electric light, contributing substantially less heat to a space for the same amount of light.

Electric lighting comprises 515,000,000 MWh or 20 percent of the nation’s electricity consumption. Of this total, approximately 10-15 percent is used to light a building’s perimeter zone where daylight is already present. For daytime-occupied commercial buildings, research projections show that total electricity and peak demand savings of 20-40 percent in lighting and its associated cooling energy can be achieved with the proper use of dimmable daylighting controls throughout the United States. Daylighting a building properly is like adding an alternative energy power plant that produces zero carbon emissions.

 

mattophoto architectural photographyDesigning for Daylight

Daylighting strategies and architectural design strategies are inseparable. Daylight not only replaces artificial lighting, reducing lighting energy use, but also influences both heating and cooling loads. Planning for daylight therefore involves integrating the perspectives and requirements of various specialties and professionals. Daylighting design starts with the selection of a building site and continues as long as the building is occupied.

**

Resources:

Architects’ Perception of Daylighting in Commercial Building Design

Daylighting Collaborative

Energy Design Resources

Concepts for daylight harvesting (PDF)

Watch for part two and three on daylighting in December and January and in “Architect’s Guide to Glass and Metal.”

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]