Krishna P. Singh Center for Nanotechnology – University of Pennsylvania


Architect: Weiss/Manfredi, New York, NY

Curtain Wall Consultant: Heintges & Associates, New York, NY

Etched Glass Manufacturer: Walker Glass, Montreal, QC

Glass Fabricator: J.E. Berkowitz, LP, Pedricktown, NJ


How do you take a 68 foot long cantilevered glass box and make it stand out even more? By adding the creativity and functionality of Walker Textures® Nuance Custom Velour Stripes to a  glass façade for a subtle and unique look from the exterior while providing shading and light diffusion for the building occupants.

This amazing building was designed by the world-renowned architectural firm Weiss/Manfredi and now is a significant architectural attraction on the University of Pennsylvania campus.

To be able to meet the architects vision, the team from Walker Glass, along with the highly-regarded building envelope and consulting firm Heintges & Associates, had a lot of work to do.  Walker has been supplying etched products like the one used on this structure for many years but every project is different and present diverse challenges.

“We were involved early in the process and we knew we had a very high-end project on our hands, so it was crucial for us to make sure that we could do everything the design called for,” said Marc Deschamps, Business Development Manager, Walker Glass.

That design included lamination, high-performance Low-E, and, what for many manufacturers would be the daunting approach of having an acid etch custom pattern on the first surface. Walker had to ensure its product could integrate into the project without disrupting the rest of the fabricated glass specified. Among the steps Walker took on this project to safeguard against defect or missing spec were:


  • Ensuring the films and the screens matched the drawings submitted by the architects;
  • Ensuring the tolerances on the position of the etched pattern on the glass were respected;
  • Ensuring the etched surface was consistent from one sheet to another; and
  • Ensuring appropriate coordination with the glass fabricator and support additional runs to cover unplanned needs.


“Our quality control program is very efficient and effective. I had every confidence that the measures we have in place would have the glass meeting the specification and vision for the project,” Deschamps added.

Meanwhile at Heintges, the responsibilities were also intense in nature.

“Our role was to collaborate with Weiss/Manfredi to transform their vision for the façade into a realistic kit of parts for construction, from start to finish. In terms of the glass, both aesthetic and performance criteria inform the façades ‘style’. We helped Weiss/Manfredi navigate these criteria throughout the design and product selection process,” said Justin Holdahl, Associate with Heintges.


Here are the product selection criteria Heintges considered:


  • Dimensions and thickness of Insulating Glass (informed by structural criteria, wind load analysis, manufacturer’s size constraints)
  • Low-E/Solar Control Coating Selection (coloration, reflectivity, visible light transmittance, solar heat gain coefficient)
  • Etch Pattern Selection (shape of pattern and its relationship to interior spaces, vertical lines shed exterior rainwater more effectively than other patterns)
  • “Intensity” of the Acid Etch (depth of etch into the glass, controls opacity)
  • Ceramic Frit Pattern Selection
  • Ceramic Frit Color/Opacity Selection
  • Color of Glass Substrates selected (low iron throughout)
  • Heat Treatment and Safety Glazing Requirements
  • IGU Spacer Material (fully thermally broken)
  • IGU cavity gas fill (Argon for increased thermal performance)


As the project ramped up, Heintges was a key player in the construction of the curtain wall, including that previously mentioned 68-foot long cantilevered box, with oversight of the visual mock-ups, laboratory testing, shop drawing, calculation review, and periodic factory and site inspections.

The etched glass usage on this project is distinctive in how it was designed into the project, but overall usage of etched glass continues to trend upward.

“Our office has been researching/developing alternative glass material for many years. Recently, this effort includes past Weiss/Manfredi projects including the Diana Center at Barnard College as well as Novartis Office Building 335 (which was developed concurrently with the Singh Center). Acid etched glass was investigated on all three projects, albeit with different intent and result each time. The glass for the Singh Center is unique in some sense because, to my knowledge, it is the first time a patterned acid etch has been used on the exterior of an insulating glass unit which includes a Low-E coating on its outboard lite, “ Holdahl added.

Deschamps echoed that theme as well and a project as noteworthy as this one can really generate a lot of dialogue about its usage.

“Architects and designers love to see actual applications so [that] they get a better idea of results from an aesthetic/design standpoint. There are immense benefits in showing a larger scale perspective of the visual appearance of an application. In addition, the fact that the project made the cover of the Architectural Record built a lot of credibility from the architectural community,” he said.

As noted, this project has become a major star both for people to visit and for various trade publications to profile. In addition to being featured on the cover of Architectural Record, positive reviews and spotlights were added by the Philadelphia Inquirer, Architizer and others. While many will notice different aspects about this design, the use of the etched glass will be remembered and appreciated for the performance it provided.

Walker Textures® Nuance is a custom acid etch pattern that has been used in many applications throughout North America. There are several options available for the architect and designer to reach their desired result. For more information on this product and others similar, please visit:

Heintges & Associates provides professional consulting services to architects and building owners, offering state-of-the-art expertise on the design and implementation of the building envelope. The firm’s technical staff is composed entirely of professional architects and engineers engaged in all aspects of custom curtain walls, cladding, specialty glazing, and exterior stonework. For more information visit:

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