The Kansas City, Kan., location of Arch Aluminum & Glass Co. fabricated the heat-treated low-E glass for Gallup University in Omaha, Neb. PPG Industries, Pittsburgh, manufactured the glass with its PPtG Atlantica high-performance tint over PPG Solarban 60 solar control low-E coating. Keystone Glass Co., Omaha, was the contract glazier, and Gensler's Denver office was the architect. Photo by PPG Industries, Pittsburgh, Arch Aluminum & Glass Co., Tamarac, Fla.
Architects can be a demanding bunch, particularly when it comes to glass products. They want bigger lites that perform better and look good.
For more than 30 years, fabricators and float glass manufacturers have worked to come up with solutions that satisfy architects. Their designer demands for larger sizes and higher performance have pushed glass manufacturers and fabricators to make better products. One of the largest challenges stems from the requirement for more products to be heat-treated. Larger lite sizes with low-emissivity coatings often necessitate that the products be heat-strengthened or tempered to prevent thermal or mechanical stress breakage. So, glass companies need to make products with low-E coatings that could also be heat-strengthened and tempered.
Glass manufacturers first introduced pyrolitic, or hard-coat, low-E products that were easily heat-treated by fabricators. Next came the introduction of sputtered, or soft-coat, low-Es that achieved better performance and appearance, but introduced some fabrication challenges. These first-generation soft-coat products had to be tempered before they were coated.
In the early '90s, float manufacturers came out with the first post-temperable, sputtered low-E products. These products allowed float manufacturers to provide sputtered coated glass to the fabricators to temper. While the products achieved high performance values, the glass often showed distortion after it went through the tempering process.
Both product types of tempered low-E have their strengths and weaknesses: first-generation soft coats generally have fewer distortion problems; sputtered post temperables often have shorter lead times, but are more at risk for roller wave.
Architectural Aluminum Techniques, Orlando, Fla., installed the post-temperable low-E glass at Seminole Community College in Heathrow, Fla. Guardian Industries, Auburn Hills, Mich., manufactured the glass with a low-E coating, and the Telford, Pa., facility for Oldcastle Glass completed the fabrication. Hunton Brady Architects, Orlando, was the architect.
Photo by Architectural Aluminum Techniques, Orlando, Fla.
In the past, certain applications have lent them-selves to one type of product over the other, says Jeff Haber, managing partner, W&W Glass, Nanuet, N.Y. Post-temperables have worked well for small- to mid-size nonresidential, and the first-generation soft coats for large nonresidential projects, he says.
Fabricators of post-temperables say improvements are making the products more applicable for large jobs. "When they first developed post-temperables, the manufacturers thought it would be ideal for small commercial applications," says Jeff Jensen, general manager Oldcastle Glass Commercial Projects Group, Wright City, Mo. "They didn't think that they would be applicable for large commercial projects, but that's obviously changed."
While pyrolitic products continue to be used mainly in residential applications, sputtered, soft-coat products have taken over the commercial market. Sputtered products have seen great improvements since their inceptions, with ever-improving performance and quality.
"[Companies] keep trying to one up each other with amazingly clear low-Es," says Max Perilstein, vice president of marketing, Arch Aluminum & Glass Co., Tamarac, Fla. "The winners at the end of the day are the designers and building owners."
This article will focus on the sputtered, post-temperable low-E products, identifying inherent challenges in the process, the evolution of fabrication and how they affect contract glaziers.
|W&W Glass LLC, Nanuet, N.Y. supplied the Pilkington Planar system for Genzyme Corp., Framingham, Ma. Pilkington Architectural, St. Helen, United Kingdom, fabricated the glass. The vertical walls feature insulating glass units with clear, tempered glass with a Pilkington SN low-E coating. The vertical glass fins were clear tempered glass. The roof glass was insulating and laminated, with tempered glass, also featuring the Pilkington SN low-E coating. Karas and Karas Glass Co., South Boston, Mass., was the glazing contractor. ARC/Architectural Resources, Cambridge, Mass., was the architect.|
"Post temperables really changed the game," Perilstein says. "Fabricators had to handle the products completely differently with different gloves, different cutting oils. It brought in edge deletion. People were deathly afraid of post-temperables in the mid '90s. Fast forward to today, and it's become part of the common fabric."
Roller wave distortion has been the major hurdle for fabricators to overcome with post temperables, a concern that has made some contract glaziers and architects weary of using the product.
"The premise of the product is great, but not enough attention has been put to what happens during heat-treating," Haber says. "When you start heat-treating, you're putting roller wave into the glass that gives it a distorted appearance. We've had unhappy architects, contractors and developers, but there's nothing you can do about it.
"These products have been around awhile, and have definitely improved in terms of performance and durability. The next step is for fabricators to work with [float glass manufactures] to figure out how to make a better formulation that is more easily tempered," Haber says.
Bob Rushing, pre-construction manager, Architectural Aluminum Techniques, Orlando, Fla., says he also has seen distortion problems with post temperables but some fabricators have worked hard to hone their tempering processes, and going with the best suppliers limits problems.
"When we do a post-temperable product, we try to stay with the fabricators that we know can handle the product," Rushing says. "Those that can't [handle the product] easily make the project look bad. "Some fabricators have gotten pretty good at handling these products, and we're seeing a lot less distortion than we used to."
Jensen says fabricators can overcome the challenges of post temperables with regular oven maintenance, operator training to make the proper adjustments, and establishing meaningful quality controls throughout the plant.
"We built the [Oldcastle Glass CPG in Wright City] to provide the market an option for large commercial project work, so we've focused on quality from day one and instilled it in the culture and employees," Jensen says. "We also installed state-of-the-art equipment that measures the optical quality of every lite heat-treated on-line. We set the criteria, and if the lite fails, it will reject it."
Glaziers and fabricators say architect education is critical to ensuring that the most applicable product is chosen for the job. Many fabricators have architectural sales teams that provide overall product details and product updates. Contract glaziers can work with architects in the design phase to educate customers and make recommendations for the most applicable glass types for their project based on performance criteria.
Jensen suggests building mock-ups. "You get a better idea of what the glass is going to look like compared to a 12-by-12 sample."
Haber agrees. "Problems are generally flushed out during the mock-up phase."
On projects where there isn't a mock-up, W&W Glass will provide product samples and take the architect to see a job with the same product. "The last thing you want is to produce a 200,000-to-300,000-square-foot job and then have problems," Haber says.
Perilstein says post-temperable soft coats forced companies to become better fabricators. "We had to handle the materials differently and up the sophistication."
Fabricators will have to continue to improve as the marketplace continues to demand higher performance and optical quality. "The industry as a whole, regardless of whether the glass has a high performance coating, is more focused on the appearance of the glass than it ever has been," Jensen says. "Glass has become a bigger component in the building envelope and obviously has a big impact on the overall appearance of the building. As a result, the industry has no choice but to improve."