Tackling a transportation center or high-traffic, urban project? Consider corrosion-resistant finishes

FL-Orlanda-ITF-stretchforming (2)-courtesy of Acurlite

Orlando International Airport’s South Intermodal Terminal Facility.  Photos courtesy of Acurlite

Transportation facilities, transit oriented developments and other high-traffic city centers provide the connecting points and places that compose our urban landscapes and skylines. They also can present significant challenges in protecting exterior-facing architectural aluminum products. Without proper precautions and finishes, corrosion to finished aluminum components ultimately can damage the structural integrity of the building envelope and can lead to systemic failure.

 

Windows, storefronts, entrances and curtainwalls, sun shades, canopies, skylights, column covers, rain screens and exterior panels all commonly are manufactured from aluminum and integrally connect to a building’s façade. In almost any city, these architectural aluminum products are continually exposed to not only weathering, but to pollution and chemicals, as well as bumps and scuffs of pedestrians. While salt spray performance considerations usually are reserved for coastal conditions, it’s important to remember that salt mixture often is used to de-ice roads making it an equal concern in colder climates.

As a prominent part of the building’s exterior, the finished aluminum adds color and design to the project; this coating also protects the building from unsympathetic surroundings. The American Architectural Manufacturers Association (AAMA) continues to set the highest standard for architectural finishes, especially in highly corrosive environments. When selecting a coating that will be required to withstand such conditions, select either the highest-performing organic paint coating that meets the AAMA 2605 specification, or a Class I anodize that meets AAMA 611.

Orlando-_-ITF-webHigh-Performance Painted Coatings

High-performance, 70 percent polyvinylidene fluoride (PVDF) resin-based coatings give architects, specifiers and building owners the capability to select nearly any conceivable color or combination of colors, while shielding the building against weathering, pollution and aging.

PVDF is known for its exceptional chemical stability and excellent resistance to ultraviolet (UV) radiation. It is used in architectural applications as a coating on aluminum where it provides exceptional resistance to environmental exposure.

Cedar Avenue Transit Station-2

Minnesota’s Cedar Grove Transit Center Photos courtesy of Protean Construction & Mark Long

The carbon-fluorine bond, used in the 70 percent PVDF, including Kynar® 500 resin-based architectural coatings, is one of the strongest bonds known. These paint coatings can withstand enduring and intense UV radiation. Such attributes support long-term color- and gloss-retention, and chalk-resistance.

 

These highest-performing 70 percent PVDF coatings meet the most stringent, exterior, architectural specification AAMA 2605, “Voluntary Specification for High Performance Organic Coatings on Architectural Extrusions and Panels.” This specification requires paint coatings to meet rigorous testing performance standards including more than 4,000 hours of salt spray, and heat- and humidity-resistance.

Protean - Cedar Grove TransitCorrosion-Resistant Requirements

Section 8.8 of AAMA 2605 refers to the corrosion resistance requirements of all coatings that must pass these stringent guidelines:

  • Humidity –The sample is exposed in a controlled heat and humidity cabinet for more than 4,000 hours at 100 degrees Fahrenheit and 100 percent relative humidity. No formation of blisters to extent greater than “few” blisters, as defined by ASTM D714.
  • Cyclic corrosion testing (previous referred to as salt spray resistance) – Score the film sufficiently deep to expose the base metal. Expose the sample for 2,000 hours according to ASTM G85, Annex A5, dilute electrolyte cyclic fog/dry test. The sample must score a minimum rating of 7 on scribe or cut edges and a minimum blister rating of 8 within the test specimen field, as defined in ASTM1654.
  • South Florida exposure – The coating shall maintain its film integrity, color retention, chalk resistance, gloss retention and erosion resistance properties for a minimum of 10 years on the south Florida on-fence testing site.
  • Color retention – Maximum of 5ΔE Units (Hunter) of color change after the minimum 10-year exposure test. A ΔE unit is the variance or color difference measured on a vector scale from a specific point in the color space.
  • Cedar Avenue Transit Station-1 399X440 Duranar MICAChalk resistance – Chalking shall be no more than that represented by a No. 8 rating for colors and No. 6 for whites after 10 years of test fence exposure. Per ASTM D4214, chalking is measured on a numerical scale with higher numbers representing better chalk resistance.
  • Gloss retention – Gloss retention shall be a minimum of 50 percent after the 10-year exposure testing, as described by ASTM D 523.
  • Resistance to erosion – Less than 10 percent film loss after the 10-year exposure testing
  • AAMA notes that high humidity environments such as, but not limited to, seacoast or industrial environments, performance of corrosion resistance may be diminished.

 

Metro Transit shelter

Metro Transit’s New BRT Shelters Photos courtesy of Duo-Gard

High-Performance Anodize Finishes

 

Class I anodize finishes that meet or exceed all requirements of AAMA 611 “Voluntary Specification for Anodized Architectural Aluminum” also resist the ravages of time, temperature, corrosion, humidity and warping. Anodized aluminum withstands extreme temperature changes and weather conditions, constant exposure to vehicle exhaust, and daily use by passengers. Over-sprayed salt de-icing can be managed with a simple rinsing as needed. With basic cleaning and maintenance, architectural aluminum products enjoy a long life cycle.

Metro shelte3The anodizing process, because it is an integral part of the substrate, produces an oxide film that is uniform, hard and protects the rest of the aluminum substrate from deterioration – providing excellent wear and abrasion resistance. The coating produced is extremely durable, and the hardness of the surface is comparable to a sapphire—the second hardest substance on earth. This characteristic makes anodize an ideal choice for use in high-traffic areas where resistance properties are important.

TForge_2400-web

New York’s The Forge.   Photos by Arch Photo, Inc., Eduard Hueber

In the most challenging applications, anodize aluminum will perform as specified and will not reduce the service life of the aluminum, but may affect the natural beauty of the surface finish. Avoid any conditions that quickly can corrode an anodize finish such as mortar, cement and other alkaline materials.

To meet AAMA 611 requirements, Class I anodize must have a dry film minimum thickness of 0.7 mils to pass these stringent guidelines:

  • Abrasion Resistance (Michael Clarke Test) – A go/no-go abrasion test using abrasive papers coated with silicon carbide, garnet and glass, respectively. This is used to discriminate between films of the correct hardness and those that may give poor service because they are too soft. The specification grade of abrasive paper is Abrasive Type: Glass, Grade: “Flour,” Mohs’ Hardness Scale Number: 4.5-5.5.
  • Corrosion Resistance testing (previous referred to as salt spray resistance) –Expose the sample for 3,000 hours according to ASTM B117 using 5 percent salt solution. Test samples shall show no more than a total of 15 isolated spots or pits none larger than 1 mm in diameter, in a total of 381 cm of test area grouped from five or more test pieces.
  • South Florida exposure – The coating shall maintain its color retention, gloss retention and erosion resistance properties for a minimum of 10 years on the south Florida on-fence testing site.
  • Color retention – Maximum of 5ΔE Units (Hunter) of color change after the minimum 10-year exposure test.
  • Gloss retention – Gloss uniformity shall be within established gloss range.

 Durability and Sustainability

TForge_018-webAnodized aluminum is an inert, non-combustible material that is 100 percent recyclable and poses no health risks. At the beginning of the new millennium, Linetec and other environmentally responsible finishers, changed from the traditional caustic etching process to a more eco-friendly etch system allowing customers to use secondary (recycled) billet in the anodize process.

Small surface defects, such as those common in recycled material, are hidden by the eco-friendly anodize finish’s “frosty” matte appearance. Architects prefer the aesthetic of this matte finish. The resulting surface also reduces glare in bright sunlight. Gloss level reading is typically reduced from 15 to 25 with conventional anodize, down to a gloss level of 3 to 12 for eco-friendly color anodize.

The eco-friendly anodize process reduces landfill waste used with conventional etch processes by 75-80 percent. Landfill waste directly relates to the production of greenhouse gas. It also has the viscosity of water and will not collect in the small recesses of aluminum extrusions or narrow aluminum tubes, which enhances the durability and lifecycle of the finished architectural aluminum product.

cedar-ave-transit-berg-170607-8198-o.jpgFor painted architectural aluminum products, Linetec and the leading paint manufacturers recommend the use of a PVDF-based paint system on aluminum material for all corrosive environments. Offering the longest lifecycle, a 70 percent PVDF resin-based coating system, pretreated with chrome phosphate, along with an inhibitive chrome-rich primer should be used. This coating type meets or exceeds all the requirements of AAMA 2605.

Beyond ensuring the highest quality application, Linetec also is recognized as an industry-leading environmentally responsible finisher. It also captures the liquid paints’ volatile organic compounds (VOCs) content using a 100 percent air capture system and safely destroys the VOCs with a regenerative thermal oxidizer. Linetec then re-uses its heat energy byproduct to improve process energy efficiency. This process of re-use is completed before the material exits the paint line.

LinetecBrushedStainlessAnodize-web3Specification and Selection

To ensure the finish specified on your project’s architectural aluminum products contribute to its long life, durability and sustainability, download a free PDF of “Section 05 0513 Shop Applied Coatings for Metal 3-part Guide Specification.”

For personalized assistance in selecting the finish for your next transportation or high-traffic project, please contact us and we’ll be happy to assist you.

 

Choosing architectural painted coatings – 70% PVDF, 50% PVDF, Baked Enamel – What’s the difference?

man hands on window frameWhen selecting high-performance architectural coatings for aluminum building products including window, curtainwall, storefront, entrance and panel systems – there are three main choices for durable painted finishes: 70% PVDF, 50% PVDF and baked enamel.

70% PVDF resin-based coatings offer the ultimate protection in building performance.

No other coating system can withstand the rigors of nature and time like those based on the polyvinylidene fluoride (PVDF) resin, such as Kynar 500® or Hylar 5000®. The resin system determines the properties and performance of the paint. In a 70% PVDF coating, 70% of the resin component is PVDF.

Ideal for high-performance exterior-facing building products, 70% PVDF resin-based coatings meet the industry’s stringent requirements set by the American Architectural Manufacturers Association – AAMA 2605. They exhibit outstanding resistance to humidity, color change, chalk, gloss loss and chemicals to ensure a long lasting, durable finish.

Linetec-paint-chips-(9)-web-smallerAmong the most popular and reliable 70% PVDF resin-based coating families are:

  • AkzoNobel TRINAR®
  • PPG DURANAR®
  • Valspar Fluropon®
  • Sherwin-Williams SHER-NAR®

50% PVDF resin-based coatings offer an intermediate level of exterior protection.

Architectural painted finishes with 50% PVDF resin-based coatings that meet the AAMA 2604 specification provide good color and gloss retention in exterior applications. These coatings also offer good hardness and abrasion resistance, making it a frequent choice for storefront, doors, or other high-traffic areas.

Among the most popular and reliable 50% PVDF resin-based coatings are:

  • AkzoNobel ALUM*A*STAR® and ALUM*A*Escent®
  • PPG ACRYNAR®
  • Valspar Acroflur®

Baked enamel coatings offer a lower level of protection, typically for interior metal products.
Baked enamel finishes are acrylic/polyester coatings. Meeting the AAMA 2603 specification, the coatings are a one-coat system with poor resistance to color fading and chalking. For these reasons, they typically are used for interior applications where color retention, chalk, fade and weatherability is not required.

Among the most popular and reliable baked enamel coatings are:

  • AkzoNobel ACRA-BOND® ULTRA
  • PPG DURACRON®
  • Valspar Flurocryl

Learn more about architectural paint types by clicking here. For personalized assistance in selecting the best high-performance architectural coating for your aluminum building products, please contact Linetec’s regional sales managers, email sales@linetec.com or call 888-717-1472.

 

What is Kynar?

Kynar - PVDF resinKynar or Kynar 500® is not a finished paint. It is a trade name for PVDF (polyvinylidene fluoride) resin, as is Hylar 5000® also a trade name.

PVDF resin is the raw material used by licensed formulators to manufacture PVDF based coatings. When formulated into a coating composition, the paint contains a minimum of 70% by weight of Kynar 500 resin to manufacture a 70% PVDF resin based coating, that meets the highest performance criteria of AAMA – 2605.

PPG manufactures Duranar®, Valspar manufactures Fluropon®, and Akzo Nobel manufactures Trinar® – all are examples of 70%  PVDF coatings that utilize the Kynar 500 and / or Hylar 5000 resin.

The key to a products performance is the resin chemistry. For the ultimate long-term durability, time has shown that PVDF resin is the one to choose. Other coating resins include acrylic, polyester, silicone polyester and urethane.

Why Specify Kynar 500?
To be both functional and decorative, metal must be coated with a finish that beautifies with color and doesn’t chalk; that won’t lose its color and sheen; that won’t pit, chip, or age before its time. No other coating system withstands the rigors of nature and time like thosekynar500_square based on Kynar 500® resins. This high-performance fluoropolymer resin, with its extraordinary capability to retain color and gloss, keeps painted metal looking
vibrant and appealing.

As a resource for architects, spec-writers and project managers, Linetec has prepared a non-proprietary CSI 3-part guide specification for superior, sustainable high-performance PVDF architectural finishes. (05-0513 Shop-Applied Coatings for Metal). This specification can be downloaded from the Architect Recourse Center of Linetec’s website

Arkema is the manufacturer of Kynar & Kynar 500 resin. Solvay is the manufacturer of Hylar 5000 resin.

 

 

Adding a Clear Coat to a PVDF (Kynar) Paint Coating

MIT Media Lab,  courtesy of Doralco

MIT Media Lab, courtesy of Doralco

70% PVDF coatings offer the ultimate protection in building performance. These finishes exhibit outstanding resistance to humidity, color change, chalk, gloss loss and chemicals. These sustainable coatings will ensure a long-lasting, durable finish. No other coating system can withstand the rigors of nature and time like those based on the Kynar 500 resin.

70% PVDF coatings include standard color two-coat systems, consisting of a primer and color coat; two-coat mica systems, also consisting of a primer and color coat; as well as three-coat and four-coat systems for metallic and exotic colors. The three- and four-coat systems include a clear top coat and sometimes a barrier coat. A clear top coat is required for one of two reasons, to protect and encapsulate the metallic flake in the topcoat, or to give added UV protection to bright and exotic colors. The clear coat is an essential component of three and four coat systems.

The paint manufacturer specifies by the formulation of each specific paint code when a clear coat is required on a paint coating. Adding a clear coat to a two-coat paint system is not recommended by the paint manufacturer, and will not extend the longevity or performance of the finish, or the paint coating warranty.

Touch-Up Paint – How to Apply and When to Use

What is Touch-up Paint

Upon request, and dependent on job size, applicators may supply a limited amount of touch-up paint with completed projects. Touch-up paint is supplied in small aerosol cans or bottles with a built in brush for easy application. It is intended to cover small blemishes or to touch-up exposed cut ends on fabricated parts.

The touch-up paint provided by Linetec is the same paint used on your project with a cure additive made available by the paint manufacturers. Each paint type has its own additive that changes the paint from an oven-cured product to a non-oven cured one. Touch-up paint does not have the same adhesion or durability as the factory applied coatings, and will exhibit chalking and fading characteristics at a noticeably faster rate than that of your building painted with a baked-on PVDF (Kynar®) finish. Therefore, it is recommended that touch-up paint be used as sparingly as possible, no more than a few square inches, as any touch-up will become faded in contrast with the original building color after only a few years.

What is Kynar® ADS

Field repair to interior sills damaged during installation

Kynar® ADS (Air-dry System) coatings are designed for repairing, restoring, and/or repainting the metal on buildings that have a factory applied PVDF (Kynar®) coating. Kynar® ADS can also be used for painting materials that will not tolerate the elevated bake temperatures required by spray-applied PVDF coatings. Kynar® ADS coatings can only be applied by a licensed fluoropolymer applicator, such as Linetec and its field service and restoration team.

Kynar® ADS coatings are based on a fluoropolymer-acrylic resin system, intended for use as a two-coat system. Kynar® ADS provides very good fade, chalk, UV degradation, and chemical resistance characteristics.

Warranty

When applying touch-up use extreme caution as excessive use may void the original finisher’s warranty. Because of the serious liabilities involved with field touch-up, Linetec prefers not to manufacture or sell touch-up products but will sell larger quantities (quarts) only under a no liability clause with an authorized signature.

Any job requiring Linetec field repair using ADS because of an unlikely Linetec finish issue is warranted in parallel with the Linetec factory warranty.

Field repair projects utilizing the Kynar® ADS system are warranted on an individual basis; the standard warranty for field finishing is 5 years from date of completion. Other warranty options are used depending upon the base metal condition, site location, type of damage, etc.

For directions on how to apply touch up, and when use visit our touch-up paint web page

Guide Specification for High-Performance Architectural Coatings

Linetec Guide SpecificaitonA new guide specification for factory-applied metal finishes, “Section 05 0513 Shop Applied Coatings for Metal 3-part Guide Specification,” is available for download from Linetec’s online Architect Resources section of its website.

Prepared according to the principles of Construction Specification Institute and Construction Specifications Canada (CSI/CSC), the guide specification reflects MasterFormat™ titles and numbers as of April 2011. Linetec’s six-page document coordinates with Division 01 to address various sections pertaining to both polyvinylidene fluoride (PVDF) liquid paint coatings and anodize finishes for aluminum railings, metalwork, frames, louvers, sun screens, roof and wall panels, doors and entrances, windows and skylights, storefronts, curtainwalls, and more.

As the first-known, non-propriety guide spec offering concise language for selecting and specifying high-performance PVDF and anodize finishing in CSI three-part format for shop-applied metal finishes, this spec goes beyond the stringent standards and regulations, It offers specifiable differences that contribute to a projects long life, durability, and in turn lowers risk or involved.

This trusted, standard format improves communication among all parties involved in commercial, architectural and institutional projects. It provides consistent documentation for architects to include in the project manual and bid requests they send to contractors. This allows them to evaluate the products and services that meet the required specifications and will achieve their design goals. This helps project teams meet owners’ requirements, timelines and budgets, and in turn, lowers risk for all involved.

Download a free copy of “Section 05 0513 Shop Applied Coatings for Metal 3-part Guide Specification” and learn more about Linetec’s architectural resources

What are high-performance PVDF (Kynar) Paints

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The most commonly used paints in architectural applications in North America are called 70% PVDF or fluoropolymer paints. An example of a trade name of a PVDF resin is Kynar 500 manufactured by Arkema. High-performance paint provide a robust weathering, fade and chalk resistant, beautiful finish that should last for decades when cared for properly.