Working on a coastal project? Start with the right finish

CA-BrenHallPayamRahimian-webCoastal areas are beautiful locations for commercial and residential buildings. They also pose the greatest challenges in protecting exterior-facing architectural aluminum products from corrosion. 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. Without proper precautions and finishes, corrosion to these components ultimately can damage the structural integrity of the building envelope and can lead to systemic failure.

PortCanaveral1-(1web)As a prominent part of the buildings’ exterior, the coated aluminum adds color and design to the project; this coating also protects the building from unsympathetic surroundings. When selecting a coating that will be required to stand up to harsh coastal or corrosive environments either the highest-performing organic paint coating, that meets the AAMA 2605-11 specification, or a Class I anodize coating that meets AAMA 611-12 should be selected. AAMA continues to set the highest standard for architectural coatings, especially in a coastal or highly corrosive environment.

High-performance 70% polyvinylidene fluoride (PVDF) 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 UV radiation. It is used in architectural applications as a coating on aluminum where it provides exceptional resistance to environmental exposure. The chemical structure of PVDF is:chemical structure PVDF

The carbon-fluorine bond, used in the 70% PVDF, Kynar 500 resin-based, coating is one of the strongest bonds known. These paint coatings have the ability to withstand enduring and intense UV radiation, attributed to long-term color- and gloss-retention, and chalk-resistance.

TampaMuseumArt-AccuratePerforating-webThese highest-performing 70% PVDF coatings meet the most stringent, exterior, architectural specification AAMA 2605-11. 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.

Section 8.8 of AAMA 2605 refers to the corrosion resistance requirements of all coating 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 38ºC (100ºF) and 100% 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.
  • Chalk 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% after the 10-year exposure testing, as described by ASTM D 523.
  • Resistance to erosion – Less than 10% film loss after the 10-year exposure testing.

Linetec, and the leading paint manufacturers, recommend the use of a PVDF-based paint system on aluminum material for all coastal and corrosive environments.Offering the longest lifecycle and true sustainability, a 70% PVDF (Kynar) 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 the highest performing “Voluntary Specification for High Performance Organic Coatings on Architectural Extrusions and Panels.”

To ensure your finish offers specifiable differences that contribute to your project’s long life, durability and sustainability, download a free copy of “Section 05 0513 Shop Applied Coatings for Metal 3-part Guide Specification”

Performance of an AAMA 2605 Paint Coating

Conservatory Interior 600X161

PERFORMANCE & LONGEVITY – SPECIFY AAMA-2605 PAINT COATINGS

Not all paint and powder coatings are created equally; not even all coatings that meet the AAMA 2605 specification. This specification requires paint coatings to meet rigorous testing performance standards including more than 2,000 hours of salt spray in accordance with the new ASTM G85, Annex 5 test and 4,000 hours heat- and humidity-resistance. For the most stringent, exterior application be sure the following pretreatment, primer and top coat guidelines are upheld.

 

PortCanaveralPainted aluminum coatings protect the building from unsympathetic surroundings. High-performance 70% fluorpolymer (PVDF) coatings can be selected in nearly any conceivable color or combination of colors, while shielding the building against weathering, pollution and aging.

 

The first, and arguably, the most important defense against a paint failure is proper pretreatment of the aluminum. Without proper pretreatment, premature failure of the finish system almost is guaranteed. Paint systems are designed to be applied over clean metal that has been properly pretreated. Pretreatment of the aluminum building components is crucial.

 

The most time-tested, proven pretreatment system for architectural aluminum products is a chrome-based conversion coating, such as chrome phosphate and chrome chromate. This process conforms to ASTM D 1730-03, Type B.

 

people-quoteOffering the longest life-cycle and true sustainability, chrome conversion coatings continue to be recognized by the world-class coating manufacturers, PPG, Valspar, Sherwin Williams and Akzo Nobel, as the most effective, robust pretreatment for aluminum. As a result, products installed along the seacoast and in other harsh industrial environments may not be warranted, or the warranty length and coverage may be compromised, if a chrome pretreatment system is not utilized.

 

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For critical adhesion between the paint and the aluminum surface, after the part has been pretreated, a primer coat is applied prior to the paint coating application. The primer coat ensures better adhesion of the paint to the surface, increased corrosion resistance, increased paint durability, and provides additional overall protection for the material being painted. Primer is designed to adhere to the aluminum surface and to form a binding layer that is better prepared to receive the paint. Because primers do not need to be engineered to have durable, weathering surfaces, they are instead engineered with specific chemistry to have improved filling and binding properties with the material underneath.

paint-system

The paint coating is then sprayed to meet the AAMA 2605 specification of a 30-microns or 1.2 mil total film thickness. When the formula of the paint coating dictates, a clear coat is applied over the paint top-coat. This protective layer shields the flake in metallic coatings and increases protection against ultra violet (UV) degradation of highly chromatic and exotic colors.

 

There are some AAMA 2605 coatings available that do not utilize a primer coat and/or may not contain a 70% fluoropolymer resin system. These coatings may perform satisfactory in color and fade, at least for the first five to ten years. However, it is Linetec’s belief, based on history, manufacturing testing and Linetec’s testing that the most robust paint finish system consists of a chrome conversion pretreatment, an intermediate primer coat, and a 70% fluoropolymer resin-based top coat.

Paint Coatings offered by Linetec that meet AAMA2605

ArchResourceImage-withLinetec-WEB2The leading manufacturers of  high-performance, 70% Polyvinylidene Fluoride (PVDF) resin-based architectural coatings are PPG, Valspar, Akzo Nobel and Sherwin Williams. 

There are several paint types within the  70% PVDF resin-based coatings family including:

  • standard color two-coat systems, consisting of a primer and color coat (top coat),
  • two-coat mica systems, also consisting of a primer and color coat,
  • three-coat metallic, consisting of a primer, color coat and clear coat,
  • three- and four-coat bright and exotic colors. These systems include a primer, color coat, clear coat and sometimes a barrier coat.

70% PVDF coatings are available in tens of thousands of different colors; however there are some bright and vibrant colors that cannot be formulated without the use of cadmium or lead in the formulation.

70% PVDF coatings are also available in some specialty formulations such as:

  • energy-efficient, solar-reflective formulations (Fluropon® SR),
  • graffiti-resistant coatings (Duranar® GR),
  • antimicrobial coatings,
  • color-changing Kameleon™  paint coatings (Fluropon).

Linetec paint offerings listed by manufacturer that meet AAMA2605-14

Vendor
70% PVDF System Paint Finish Type
PPG Duranar Two-coat Standard
Duranar Sunstorm Two-coat Mica
Duranar XL Three- or Four-coat Metallic or Exotic
Valspar Fluropon Two-coat Standard
Fluropon Classic II Two-coat Mica
Fluropon Classic Three-coat Metallic
Fluropon Premiere Three-coat Bright or Exotic
Akzo-Nobel Trinar Two-coat Standard
Trinar Ultra Two-coat Lower VOC levels
Tri-Escent II Two-coat Mica
Trinar TMC Three-coat Metallic
Trinar TEC Three-coat Exotic
Sherwin Williams Shernar Two- or Three-coat Standard, Mica, Metallic or Exotic

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