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National Capital Planning CommissionRevised Final Design

Corona Panel Finish and Landscape Materials

February 6, 2014

THE FREELON GROUP, INC5310 South Alston AveBuilding 300 Suite 320Durham, NC 27713

OFEO# 0927102A / 0927102B

SmithsonianNational Museum of African AmericanHistory and Culture

National Capital Planning. Commission Revised Final Design - February 6, 2014 | FREELON ADJAYE BOND SMITHGROUP 1

Design Table of Contents

The following design changes reflect comments and suggested direction received from CFA staff.

A Corona Panel Finish

01 Corona Panel Finish 3

B Landscape Material Finish Palette

01 Landscape Material Finishes in Context with Corona 9

Smithsonian Institution National Museum of African American History and Culture 2

Corona Panel Design Intent and Vision for the Finish:

The corona is the central design feature of the NMAAHC and one of the three irreducible elements as identified very early in the project. In Yoruban art and architecture, the column or wooden post was usually crafted with a capital resembling a crown. Reaching toward the sky, the corona expresses faith, hope and resiliency. Internal to the building, the corona forms a perimeter zone which surrounds the primary galleries and other program elements. Daylight enters this zone through patterned openings in the corona cladding and through skylights – washing interior walls with light while providing views upward and outward. At night, interior lighting adds a soft glow to the corona, presenting majestic views of the museum from a variety of vantage points in and around the Mall.

The profile, materiality, color, texture and finish of the corona have been critical considerations throughout the evolution of the design from early concepts to design development to construction detailing to full scale mock-ups. The idea of having a bronze type cladding on the corona stemmed from the desire to use a classic and elegant material that conveyed dignity, permanence and beauty. Color, richness, and luster were also important design considerations as these attributes would give the building a presence and luminosity that would shift subtly throughout the day, and from season to season.

Many materials have been studied over the months with the goal of identifying a contemporary cladding system that could provide color, richness and luster while meeting the performance, aesthetic and aspirational goals of the project. This document includes a matrix of corona cladding alternatives that have been studied along with the evaluation criteria which was used to vet each potential option.

Images from Previous Corona Development Presentations


A.01Corona Panel Finish

Corona Panel Development:Through Historic Precedent

The design team researched the historic precedents of African American iron work and railings from Charleston, SC and New Orleans, LA to develop the pattern of the corona panels. The 18th and 19th century ornamental patterns were interpreted and transformed to a modern motif by abstracting the pattern of the historic grille work into a new triangulated pattern for the corona panels. The new pattern is used in varying densities to modulate the opacity of the panels from 65% - 90% solid. This range of opacity allows certain views from the building to be emphasized while providing control of solar heat gain and glare.

The form of the corona is also linked to its most important neighbor - the Washington Monument. The angle of the corona matches the angle of the Washington Monument’s pinnacle and capstone – 17 degrees. The historic precedent of the Washington Monument was also used as a reference in developing the corona panel size and pattern. Studies were done of different possible sizes and patterns for the corona panels and how they would relate to both human scale and the overall corona façade.

Images from the Research of Historic Precedent


Summary of Previous Presentations and Agency Comments:

On June 19th, 2013 the CFA staff, SI and the A/E team visited the construction site to view two corona panels that were erected at the south end of the site. Several of the CFA commissioners also viewed the panels independently.

The following Commission comments, contained in the Commission’s letter of June 27, 2013, expressed their concerns.

“In their discussion of the inspection, the Commission members observed that the corona is the single most important element of the entire project which establishes the iconic identity of the museum; they noted that the original design intent for the corona material was to be bronze to create a shimmering, lustrous effect under many lighting conditions. Thus they expressed their strong disappointment with the two mockup panels presented, characterizing the Kynar finishes as putty-like, muddy, and dull falling far short of the beautiful poetic intention promised by the concept design. Instead they recommended the consideration of other finishes, such as an applied and burnished coating containing actual bronze as was shown to the staff and other consulting parties last December, to achieve the magical quality that is critical to the success of the project.”

“In conclusion, the Commission requested a diligent search for alternatives and advised that this review provides the Smithsonian the opportunity yet to achieve the quality that this important national museum deserves.”

The A/E response to these concerns was to explore further, the alternative finishes, while continuing the construction of the performance mock-up. In August 2013, the Commission staff traveled to York, Pa. to observe the corona performance mock-up. The following photos and data show the results of this mock-up and the subsequent exploration, resulting in a detailed evaluation matrix. The analysis of the corona finish alternatives is contained in this matrix, which established criteria that included the stated goals, set forth by the Commission, for the corona finish.

Sample panels shown above represent one of four levels of transparency. These panels were 75% opaque. The panels shown below represent the range of opacity that will be used in the design. Based on observation of the panels at the site, the Smithsonian requested additional pigment variations for the performance mock-up in York, PA.

TYPE 165% Opacity

TYPE 375% Opacity

TYPE 585% Opacity

TYPE 690% Opacity

Sample panels shown represent one of four levels of transparency. These panels are 75% opaque. Other panels in the design will be 65%, 85% and 90% opaque as shown below. Based on observation of these panels at the site, the Smithsonian has requested additional pigment variations for the performance mockup in York, PA.

Corona Panels with the range of opacity

Corona Panels with the June-September 2013 Finish at the on-site review


Corona Panel Finish: as displayed at the Performance Mock-up

Another important step in the design and development of the corona was the building of a full scale mock-up at a testing facility in York, PA. A portion of two tiers of the full corona assembly including steel structure and glass curtain wall with opaque panels was erected. A range of corona panels, including various opacities and coatings, were set up for viewing and evaluation. Representatives from SI, the contractor, the A/E team and CFA staff visited the mock-up on August 5th, 2013.

On September 19, 2013 the Smithsonian Institution presented to the Commission of Fine Arts the Corona panel sample with the June - September 2013 PVDF finish (Color #6) and expressed concern “that key aspects of the compelling design are not being developed as originally intended”. The Commission urged the Smithsonian “to remain faithful to the quality of concept and materials that this museum deserves”.

The following Commission comments contained in the Commission’s letter of September 27, 2013, expressed this concern:

“Noting again the importance of the corona as the most iconic element of this new institution, the Commission members reiterated their support for the use of actual bronze in the finish of the character-defining corona panels. Dissatisfied with the presented choice to use a metal-colored polymeric painted finish (Duranar) instead of bronze, they recommended that a finish containing real bronze material be used. They observed that the Duranar paint finish imparts a putty-like appearance under overcast conditions and will not behave like bronze over time; alternatively, they noted that the mockup panel of LuminOre, a finish containing bronze metal is far superior in its depth of color, richness, and luster.”

With these expressed concerns in mind, the designers set about to reconsider previously explored materials, including LuminOre, as well as new potential materials, and to evaluate the options available which would satisfy the Commission’s charge that the remaining design issues “be resolved in a way that honors the momentous purpose and monumental presence of this museum for generations to come”.

Several options followed that explored the range of alternatives to the Corona panel finish. The goal was to find an alternative that had a depth of color, richness, and luster. A detailed evaluation was conducted for this purpose. The results of this evaluation follow and concludes with a preferred recommendation.

90%

85%

75% 90% 90% 90%

90%90%

90%

90%

75% 75% 75% 75% 75%

85%85% 85% 85% 85%75%

75% 75% 75% 75%85%65%

65% 65%65%

65%65%65%65%65%65%

65%65%65% 75%75%

75% 85%85%85%

85% 85%75%

Color #6 June -September 2013 PVDF Color #5 Color #7 Color #4

LuminOre Panel

Corona Panel with the June-September 2013 Finish at the Performance Mock-up in York Pa.


Evaluation Criteria 3 Coat Metallic Polyvinylidene Fluoride (PVDF) Finish on Aluminum Casting

LuminOre Finish on Aluminum Casting Electro-less Plating on Aluminum Casting Anodized Finish on Aluminum Casting Physical Vapor Deposition (PVD) Finish over chrome nickel strike on Aluminum Casting

5 Coat Metallic Polyvinylidene Fluoride (PVDF) Finish on Aluminum Casting ("Custom Artisan Finish")

RECOMMENDATION: Eliminated: due to unachieved visual/ emotive goals

Eliminated: due to high risk of performance and production factors.

Eliminated: due to high risk of durability and performance factors. (Material weight is an additional factor.)

Eliminated: due to failure of anodizing on cast aluminum panel.

Test Samples Disappointing: do not achieve visual/ emotive goals; technical goals are challenging.

Best Option: best achieves visual/ emotoive, technical, schedule & cost goals.

1.) A-E Visual Criteria: 1) Bronze; bright with a slight golden brown hue, 2) metal-like appearance, reflective; not matte finish, 3) sculpted with relief on both interior and exterior facing surfaces

Samples included at project site and performance mock-up. Samples included at project site and performance mock-up. Plating with actual Bronze might have met visual criteria, but no samples were obtained as option proved infeasible.

Test sample attempted by Superior Metals, Indianapolis, IN failed to bond to cast aluminum substrate.

1) PVD has the ability to create a number of metallic golden brown hues. 2) The finsh coating is clear metal with pigmentation for color. 3) Substrate smoothness necessary for reflectivity. 4) The coatings are completely conformal to the substrate material.

(4) sample panels provided representing incremental variations in the range of gold-green and bronze-red hues; finish is reflective and appears metal-like. A Custon Artisan (gold-green #1) was included at performance mock-up.

2.) A-E Emotive Criteria: 1) Avoid seeming monolithic, overly consistent, 2) express gravitas, permanence consistent with the Monumental Core, 3) enliven Corona by responding to changing levels and quality of light, 4) evoke the representation of a substantially thick and respectful material.

Samples included at project site and performance mock-up. Samples included at project site and performance mock-up. Plating with actual Bronze might have met emotive criteria, but no samples were obtained as option proved infeasible.

Test sample attempted by Superior Metals, Indianapolis, IN failed to bond to cast aluminum substrate.

PVD sample is monolithic and uniform in appearance and matte finish results from roughness of the sand blasted substrate, failing to achieve the emotive criteria desired. It is possible that if the aluminum casting would first be polished, the results would be more reflective and nuanced.

1) Finish is varied with highlights, providing depth; 2) Finish has lustrous character of polished metal; 3) Character of finish, coloration and reflective highlights change with viewing perspective and the angle and quality of light; 4) Appearance of a heavy cast polished metal.

3.) Corona panel material substrate: cast aluminum with smooth surface and crisp definition of edges and formal expression.

Cast aluminum substrate with PVDF finish is provided by single entity within the exisitng exterior enclosure contract.

Cast aluminum substrate is to be provided by the panel casting fabricator and prepared for the application of LuminOre "Bronze"

No sample was attempted on cast aluminum project panel. Test sample attempted by Superior Metals, Indianapolis, IN failed to bond to cast aluminum substrate. Finisher offered to coat the panel with Kynar 500 finish to match anodized color.

PVD has been succesfully applied to properly prepared aluminum substrates. Note that the Olympic Torch project was on a prepared aluminium substrate (note the size of components are typically smaller than a full corona panel); US based finishing equipment cannot currently support a full corona panel, but custom equipment may be possible. Finishing can be done in the Netherlands.

Cast aluminum substrate with PVDF finish has been successfully provided by single entity within the exisitng exterior enclosure contract.

4.) Finish System: General Description PVDF refers to polyvinylidene fluoride resin, pigmented, coating system containing not less than 70 percent of the fluoropolymer resin Kynar 500 or Hylar 5000. ( Duranar - PPG and Fluropon - Valspar are manufacturer trade names.) Metallic flake adds a unique vibrancy caused by the way visible light is reflected off the metallic flakes.

LuminOre is a patented metalizing process using a seamlessly applied composite metal (bronze, copper, aluminum, etc.) on nearly any surface. Composite metals are bound with a polymer to act as an adhesive. The metal and the polymer binder interact in a chemical reaction creating an stable, homogeneous composite.

Nickel strike base coat with bronze plated finish coat and a clear coat sealer to prevent additional patina of the bronze.

Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish.

Physical Vapor Deposition is a vacuum plasma coating process capable of depositing extremly hard, durable and chemically resistant pigmented ceramic coatings. The the visible materiality is a tinted metal finish

PVDF refers to polyvinylidene fluoride resin, pigmented, coating system containing not less than 70 percent of the fluoropolymer resin Kynar 500 or Hylar 5000. ( Duranar - PPG and Fluropon - Valspar are manufacturer trade names.) Metallic flake adds a unique vibrancy caused by the way visible light is reflected off the metallic flakes.

5.) Application Method Non-charged electrostatic hand spray application; five step process: chemical etch to clean aluminum substrate, base coat, middle coat (visible pigmentation), clear coat, baked. All within a single product system.

Cold metal atomization process that deposits a veneer of real metal (bronze, copper, aluminum, etc.) to the substrate surface. Polishing achieves the desired luster and then is sealed with a ceramic clear coat to achieve gloss and prevent oxidation/ corrosion.

Electroless process is a acid bath process - that provides a base Nickel plate coat - to seal aluminum - afterward the bronze or copper could be electroplated over the nickel base - which is a chemical bond of Metal onto nickel. A clear coat is applied on top.

Electrochemical process that modifies the aluminum substrate by fusing coloring chemicals to the aluminum. Usual application is on extruded or coil stock. Cast shapes require specific surface chemistry for anodizing; which failed in this effort.

Nickel chrome plating for base coat and cathodic arc vacuum plasma deposition for finish coat.

Non-charged electrostatic hand spray application; ten step process: chemical etch to clean aluminum substrate, pigmented prime coat, baked, 2nd coat of pigmemented prime, baked, custom pigmented "black", baked, custom pigmented top coat, custom tinted clear coat, baked. All within a single product system.

6.) Finish System: Application Components (3) coat system consists of the following:1.) primer coat (0.25 mil dry film thickness-DFT)2.) color coat with alum. flake ( 1.0 mil DFT)3.) clear top coat (0.6 mil DFT)

The bond between the different coats has been tested and is part of the PVDF coating offered by the manufacturer. Bond between the subtrate and coats of the finish will not be an issue to consider.

1.) - LuminOre is applied to an average thickness of .010” 2.) After curing, LuminOre composite is machine polished by hand to achieve the desired luster.3.) Clear coat MC-156 is applied on top of LuminOre metaized bronze to provide UV stability and protection from corrosion and staining of the metalized coating. Luminore states there is no issue with bonding between LuminOre and the ceramic clear coat nor between Luminore and the aluminum substrate.

1. Nickel strike is an average of .001" thick 2.Bronze plating with an average of .008"over nickel strike 3.Clear coat is applied over bronze plating to prevent patination

Anodizing is accomplished by immersing the aluminum into an acid electrolyte bath and passing an electric current through the medium. A cathode is mounted to the inside of the anodizing tank; the aluminum acts as an anode, so that oxygen ions are released from the electrolyte to combine with the aluminum atoms at the surface of the part being anodized. Anodizing is, therefore, a matter of highly controlled oxidation—the enhancement of a naturally occurring phenomenon.

The coating system consists of the following:1.) An electroplated or electroless nickel base coat to the cast aluminium to provide corrosion protection and a support for the PVD coating.2.) A final PVD layer consisting of an approximately 1 micron thick pigmented ceramic coating.

(5) coat system consists of the following:1.) primer coat (0.25 mil dry film thickness- DFT) 2.) prmer coat (0.25 mil DFT)3.) color coat with alum. flake ( 1.0 mil DFT) 4.) color top coat with alum. flake (1.0 mil DFT)5.) tinted clear top coat (0.6 mil DFT)

The bond between the different coats has been tested and is part of the PVDF coating offered by the manufacturer. Bond between the subtrate and coats of the finish will not be an issue to consider.

7.) Application Track Record - Location All temperature and humidity conditions: high end, most UV and weather resistant for architectural aluminum.

Exterior applications include Singapore, London, China, Dubai, Las Vegas, Saudi Arabia, Abudabi, Tijuana

Used widely in aviation industry for internal applications. Anodized aluminum has been used as building material for may years, domestically & internationally. No similar architectural applications provided. More typically used as curtainwall extrusions and panelized sheet product.

1) Olympic Torch Project in England 2) Wire mesh on building in the Hague, NL 3) Gaming industry 4) Retail fixture industry 5) Exterior Architectural Hardware 6) Jewelry

All temperature and humidity conditions: high end, most UV and weather resistant for architectural aluminum.

8.) Application Track Record - Quantity: Project requirement is 140,000 sf finish surface

PVDF-Practically unlimited square feet throughout the world, including the world's two tallest buildings, Petronis Towers and Taiwan 101.

Largest exterior application 20,000 sf (surface area appears to be exaggerated) for Gucci Singapore; 4,000 sf for 45 Park Lane Hotel in London.

No examples found on buildings. Durability is an issue as deterioration of top coat and then exposure and wear of metal plating finish require frequent reapplicaiton.

Limitless applications on extruded and coil stock. Performance and durability tesing dates back to 1960s. Applications on cast stock remain elusive.

Only building example known, double sided wire mesh screen application in the Hague, Netherlands for 3,000sf. Worldwide applications for exterior architectural hardware and plumbing fixtures.

PVDF-Practically unlimited square feet throughout the world.

Evaluation Matrix:


Preferred Corona Panel Finish:

The corona panel finish was benchmarked against an applied bronze finish known as LuminOre. Due to high risk of performance and production factors, this product was eliminated from consideration as an optional finish. However the color and luster of the LuminOre panel became the basis for further investigation.

Options researched included Electro-less Plating, Anodized Aluminum finish, PVD (Physical Vapor Deposition), and PVDF (Polyvinyl Difluoride) “Custom Artisan”.

Electro-less Plating was rejected for reasons of durability. The bronze was applied over a nickel chrome strike, to seal the aluminum, and then clear coated. Both the clear coating and the bronze plating have a limited life span; five years for the clear coat and 10 years for an exposed bronze plate. Therefore this application was not viable. Additionally the material weight was a factor in its elimination from consideration.

The Anodized Aluminum finish was eliminated due to the failure of the anodizing process on the cast aluminum.

The PVD process vaporizes metal, in this instance Zirconia, onto the nickel chrome coating over the aluminum casting, was also given consideration. The PVD finish is robust, long lasting and resistant to corrosion. However because the nanometer thickness of the material follows identically to the profile of the substrate, resulting in an undesirable uniform finish as discussed with the CFA staff on January 31, 2014. The PVD test samples did not achieve the visual nor the emotive criteria established in this evaluation.

PVDF coating, “Custom Artisan”, has been the most successful in simulating the appearance of real bronze. The location and depth of color has been developed to approximate shadow and brightness and give the corona panel the desired luster and richness in appearance.

PVD - Ionbond - Quarter size panel PVDF “Custom Artisan #4” - Full size panel

Corona Test Panels - PVD and PVDF - “Custom Artisan” on site.


Landscape Material Finishes in Context with Corona:

This material palette will be presented at the NCPC Presentation

1 2 3

89 7

6

4 5Legend

1. Granite - Impala Black, thermal finish, North Plaza, Oculus Roof

2. Granite - Crystal Black, honed finish, Security Walls

3. Reading Grove Metal Bench (color to match building mullions)

4. Concrete at Promenade

5. Bronze Handrail at Stairs

6. Exposed Aggregate Concrete at Sidewalk

7. UHPC - Porch Column (Custom Color)

8. Granite - Crystal Black, polished finish, North Security Wall Top

9. Granite - Crystal Black, thermal finish, South Plaza


B.01Landscape Material Finish Palette

Site Material Key Plan


1. Granite - Impala Black, thermal finish, North Plaza, Oculus Roof 2. Granite - Crystal Black, honed finish, Security Walls

3. Reading Grove Metal Bench (color to match building mullions)

4. Concrete at Promenade

5. Bronze Handrail at Stairs

6. Exposed Aggregate Concrete at Sidewalk

7. UHPC - Porch Column (Custom Color)

8. Granite - Crystal Black, polished finish, North Security Wall Top

9. Granite - Crystal Black, thermal finish, South Plaza

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