Diamond in the Rough

New Technologies in Prismatic Glass Offer a Unique Architectural Aesthetic

By Ellen Rogers with contributions by Tara Taffera

Could they or couldn’t they? That was the question in 2011 when plans to install prismatic glass on the podium portion of 1 World Trade Center were scrapped (See related article in the October 2011 USGlass magazine). Seven years later, we now know that yes, they can. A number of global glass industry companies are producing versions of their own prismatic glass products. While they’re all somewhat different, both in terms of the way they are produced and their aesthetics, the results bring a light-manipulating, visually unique look.Aesthetics aside, prismatic glass is still a relatively new product and, as with any new product, it brings with it a learning curve, as well as unique considerations.

Dazzling Play on Light

Prismatic glass aesthetics aren’t anything like those of conventional glazing, and neither is the product itself. While there are different fabrication methods, the glass isn’t easy to produce on a large scale, and it likely never will be mass-produced. Such a special glass isn’t going to be used in every project, everywhere.

Nathan Munz is the founder and managing director of Glassform, a glass fabricator based in Victoria, Australia. His company has been working with what he calls “Truly Prismatic Glass” for over a decade. Munz also provided samples for the 1 World Trade Center project. Glassform also supplied the prismatic glass for the Baccarat Hotel & Residences in New York, which features prismatic glass fins on the podium level. The structure was designed by Skidmore, Owings & Merrill LLP.

“Really, [truly prismatic architectural glass] has only been around in a practical sense since the Baccarat,” he says. “That was what made us commercialized.”Glassform’s process involves laminating the prisms to a glass substrate to create a laminated safety glass. The company has patents for its product in Australia and the United States, with other international patents pending.

Tianjin North Glass Industrial Technical Co. Ltd. (North Glass), located in Tianjin, China, has also developed a prismatic glass product. Dirk Schulte, vice president, North America, explains the glass has deep serrations in the shape of prisms carved into the surface.

The North Glass fabrication division began developing its prismatic glass product around 2013-2014 after being approached by architects demanding it for exterior glazing applications.

“We began this task development and custom-built the machine that [we used on] our first project (in 2016), the Bloomberg Place in London, designed by architect Foster+Partners,” says Schulte. “That exterior wall design included the prismatic carved glass.”

He adds of the technique, “It’s quite a sophisticated process to get the grooves into the glass. The polishing wheels on the machine are custom-made to the size of the prismatic groove geometry and configured for individual panel dimensions, groove orientations, tolerances and surface qualities.”

Christoph Timm, associate director with SOM in New York, has worked with prismatic glass.“

We have been and currently are designing with prismatic glass on several projects,” says Timm. “It is a beautiful product—that’s rather expensive—but very special in direct daylight.”

According to Timm, prismatic glass is ideal for applications such as a high-profile lobby exterior or store-front (in a limited amount) to attract interest. And while it could be used in interior settings, he thinks it’s best-suited on the exterior.

“It’s a very dynamic glass solution that reacts to the change of direct day-light every day and throughout different seasons,” he says. “It can be used on the interior as well, but then it will lose a bit of its magic for me as it becomes more like a chandelier … still beautiful, but a bit less reactive to the environment.”

What You Need to Know

One of the original concerns with prismatic glass when it was considered for One World Trade Center was its inability to be tempered—and that’s still true.

“The glass itself always needs to be laminated to a back-up structure to ensure it’s assembled into safety glass,” explains Schulte. “The challenge is that prismatic glass is not fully temperable; heat-strengthening it is barely possible because of the deep grooves and textures being implemented. Tempering will create stress peaks all over the glass.”

These special effects offered by prismatic glass may be impressive, but they aren’t cheap. In addition to cost, there are a number of other considerations to be familiar with before bringing the product onto a project.

“Cost is a huge concern as polishing the glass is extremely time-intensive, which translates into [higher] cost,” says Timm. “Also, perfectly polished surfaces generally aren’t accomplished since the grinding tool leaves tiny little grooves in the glass—all only detect-able up close, but worth mentioning since we’re talking about a high-end product.”

Prismatic glass also requires unique installation and handling considerations.

“You can’t pick it up with regular suction cups as the prismatic surface distracts a proper vacuum suction build-up,” says Schulte. “It needs to be thought out from start to end how the panels will be glazed and installed to ensure you have [the right] method and guidelines for how these elements will be handled.”

He adds, “There needs to be a sophisticated preparation in advance of the actual installation to make sure the glass is installed properly and without damage.”

Munz says that those looking at his company’s products haven’t had installation problems. “The prismatic panel is laminated glass and one face of it is flat, so it can be handled with standard vacuum cups,” he says. “It gets trickier if the prismatic face is [toward the] outside, as you can’t use the vacuum cups on the prismatic side. You could glaze them from inside the building.”

He adds that prismatic panels can have other attributes embedded in them that can be part of a complex system that offers a number of features and benefits. For example, the product could be glazed into a double or triple IGU.

Early Preparations

Advance preparation and planning is also important to help avoid dam-age and breakage. While this is true on any project, it’s an even greater concern with prismatic glass, which is currently not produced in North America.

“Every time [you’re working with] custom glass [the process] needs to be thought through so you’re limiting any potential damage to not affect the schedule and budget,” says Schulte, who adds that working closely and cooperatively with the architectural design team is critical. For example, he says tools for custom prismatic geometries and patterns may not be in stock and would need to be manufactured on a case-by-case basis. This could extend the lead time of samples and project glass.

“We can offer technical advice and recommendations to ensure that what’s being specified and designed is producible,” he says. “Not every pat-tern geometry is technically feasible, and custom patterns require in-house testing prior to final confirmation. [Fabricators] should be involved in the design development process right from the start to eliminate unnecessary delays in the project schedules, as well as extra cost.”

Prismatic glass offers a unique aesthetic, and it could continue to grow in popularity and demand as architects and designers search for new ways to bring that coveted “wow factor” to their projects. Both Munz and Schulte say they have a number of potential clients in the U.S. and around the world.

What Does the Future Hold?

“Architects and designers are always interested in bringing texture onto surfaces to create depth for a kind of three-dimensional appearance, rather than working with a clean, flat surface,” says Schulte. “They want to build surfaces that can create awareness by the people who are observing those buildings. In the future, we may not be limited to a typical prism effect. We investigate, develop and permanently test other ornamental textures to be applied into solid glass surfaces through the milling process as well.”

But there’s at least one consideration that some believe needs to be addressed.

“It’s a beautiful product and I think the demand will in-crease—especially if glass processors invest into more efficient equipment and the cost comes down,” says Timm.

But as Munz points out, “This is a sophisticated, high-end product. We understand there will be a lot of people who want it but can’t afford it. We aren’t looking for it to be a mass-produced commodity. We expect it to be very exclusive and used where it will add substantial value to the aesthetics of a project as well as to the building into which it will be installed … sometimes you may only need 20 square meters and sometimes it’s like a diamond on the dress.”

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