Volume 43, Issue 6 - June 2008
From Silica to Siding
The Glass Fabrication and Glazing Educational Conference seminars opened to full crowds at the Monte Carlo in Las Vegas this April. The event, sponsored by the Glass Association of North America (GANA), was designed to educate individuals who have fewer than five years of experience in the industry.
As there’s always something new to learn, the conference featured two joint sessions each day that provided information on glass handling, glass production and trends in glass usage. To start in the beginning, from the trends pushing glass usage, through production and installation, read on. But if your interests are more specific, choose your own track: fabrication information is below or skip to page 76 for more on glazing education.
Give an Architect A Lite and He’s Going to Want It Coated …
“We’re starting to see more floor to ceiling glass,” McCann said. And on that glass, architects are demanding high-performance coatings. He noted that more hybrid materials are being used to get the best of all performance features, from high visible light transmittance (VLT) to low U-values.
High VLT in particular has become much in demand. And, McCann said, “That’s one of the hardest things to get an architect off of.” Not to persuade architects away from letting in more light—but educating them about what high VLT really means and how a combination of coatings can create a room that has lots of visibility and is still comfortable.
In addition, McCann said that he has seen more architects push for low U-values, which he expects will be obtained through more demand for gas filling in insulating glass units. Laminated glass also is still growing, he said, for security applications, as well as acoustics. So how to meet the demand for these trends? Well, glass fabricators were in attendance to learn just that.
Floating Through the Basics
One point he reviewed was how to add color to glass substrates.
“We learn to make different colors everyday,” Boor said, “and that is market-driven.”
As Boor noted, iron, in all glass, creates the green tint. Cobalt is added to create what he described as “true blue,” while selenium creates “more of a brown glass.” Combinations of the latter two create shades of gray. He further explained to the audience that low-iron glass means just that, removing as much iron as possible, and to do so requires a special sand with low levels of iron.
“Low-iron glass is really becoming popular in the solar and photovoltaic industry,” Boor said, adding, “they would like us to have no iron.” Of course, as he noted, “I think it’s impossible because you’re going to have some impurities no matter what you do.”
Cut Down to Size
He offered a number of suggestions for a successful cutting process, including the importance of matching the proper cutting wheel to a particular process and product.
“I prefer to think of the cutting wheels like the tires on your car,” he explained. Just as you would select a certain tire for a particular driving condition, Beatty suggests matching cutting wheels to a particular product.
Beatty also urged processors to consider the benefits of cleaning glass prior to the cutting process.
“The problem is most people don’t wash,” he said. “And the cutting environment is dusty and dirty.”
Hands Off That Coating
For instance, keep individual lites from scratching one another during the handling process. Keep coated surfaces away from conveyor rollers and harp rack separators. Even, Haberer advised, keep fingers away from the coating. And when it comes to handling that glass, be sure to use some type of clean, soft glove; touch only the edges; and handle only one lite at a time.
There’s no way to keep the glass from being handled and touched at all; it’s just a matter of doing it carefully.
For washing, for example, Haberer suggested adjusting the tip of the brushes so that they are barely in contact with the glass.
Cleanliness is Next to Successfulness
Among the tips Lang provided was this: “If the inside of the glass washer is dirty, it can’t produce clean glass.”
He reminded his audience that maintenance of these washing machines is critical to getting the best performance from the equipment and, by extension, the glass product going through it. “I can’t stress enough that the cleanliness of the glass coming out of washer is directly related to how well the washer is maintained.”
His suggested maintenance schedule starts with the first week of operation on through a 500-hour check-up.
Tensed and Shattered
Essentially, he explained, glass breaks when an applied load exceeds the strength of the glass. The real question is: when a break occurs, was the load too great or was the glass too weak?
To begin to answer that question, Barry noted, means asking how strong glass is, and that’s where the problems begin. “We don’t really know,” he said. “We know how strong it might be.”
For example, in taking 1,000 samples lites and applying force, by the time 9,000 psi was reached, eight lites still hadn’t broken.
There are a couple of common causes of breakage, however: tensile stress (including bending, thermal stress and NiS inclusion and expansion), impact and crushing. To determine what might be the cause, fractographics can be used to examine the break—if there’s enough time and money and all the pieces are still available, Barry added.
Troubleshooting laminated glass production was the next topic of discussion. Ron Hull from DuPont talked about common laminating defects and problems. One problem is PVB blocking, which occurs when the PVB sticks to itself. It’s typically caused when the storage temperature is too warm, when the rolls are wound too tightly or if the rolls are too old. To keep this from happening, Hull suggested that storage temperatures be kept cool and that the laminator has a supplier unwind and wind the roll properly. Finding bubbles in the laminate was another problem he discussed. The bubbles, Hull said, are actually gas pockets in the interlayer material or between the glass and the interlayer. “Basically, inadequate de-airing,” he said. Bubbles can be caused from a surface pattern that is too smooth or rough; from caliper/thickness variations; from stretching the PVB; and also if the PVB temperature is too high or too low.
While PVB may be the most common interlayer in use for laminated glass production, it’s not the only one available. Michael Burriss from Cytec Industries gave a presentation about ultraviolet (UV) liquid laminating. He explained that by exposing liquid resin to UV light it changes into a polymer that, in the case of laminated glass, serves as the solid interlayer. He said it takes 20 minutes for the glass to cure fully, and added that the process consumed a minimal amount of energy: 7 kilowatts. In addition, Burriss said UV-cured laminated glass meets the same safety tests as PVB laminated glass, so the products can be used wherever safety glazing is required.
Mark Gold of Solutia covered the why, what and how of laminated glass quality control testing.
“Why test?” asked Gold, “Because we have to; it’s the right thing to do,” he explained, for regulatory and code requirements, as well as protection against liability. “Also, it’s just plain, good business.”
He discussed different types of tests that can be done to laminated glass, such as the boil and bake tests.
“You can use it for anything,” Beneke said. She also took the crowd through a demonstration of using the 3D design tool, and left the crowd impressed with how quick and easy it can be to not only create a structure but also to change out components.
“Would you know what the tolerances that adjoining trades will be held to?” he asked. “You need to know the tolerances of other trades or you can end up not being able to fit in the openings with glass.”
Keeping details documented was another point Heinaman stressed.
“In our business we really can’t over-document things. It’s not possible. But we have to do it on all jobs,” he said. “You can’t document well on a big job and not do it on the little ones.”
Heinaman also discussed the importance of safety procedures for the company in general and on each job.
“Is a safety plan a requirement?” he asked rhetorically. “It sure should be. I have had very few cases where I haven’t been asked for one. If you have a large project, you should have a safety plan just for that job. This is usually accomplished by taking your standard safety program and customizing it.”
Heinaman added that most insurance companies are willing to send a representative to the jobsite.
“It’s wise for you to have them come and inspect your job. It could reduce the likelihood of an accident, could also reduce your mod rate and increase your bottom line,” he added. “Don’t assume anything. Inspect all safety equipment. You might say ‘well, gosh, of course we would do that.’ But I have heard of instances where no one checked the swing stage for frayed wires and to make sure that it’s attached to something at the top of a building. You want to check it yourself.”
“Know from the start what’s expected of you,” Wirth said. “The least expensive way to correct a mistake is not at the end; it’s before it happens.”
One specific area she covered was operational training.
“Don’t be a dictator,” she advised, “but work as a team.” She reminded her audience that when they are passing the project over to the customer they need to take the time to explain to them how they need to take care of the building.
Another discussion point was having a lien waiver.
“Anything that reduces your liability is always a good thing,” said Wirth, who suggested each company have one dedicated person on-hand who understands and documents waivers that are coming in and out. On a final note, she stressed that in project closeouts documentation is critical and encouraged everyone to keep organized all of the documents related to the job, including both paper and computer files.
Making the Code
Rob Hitchcock from Lawrence Berkeley National Laboratory followed with a discussion about COMFEN software, which is used to provide a whole building calculation. Version 1 of COMFEN, which was launched last fall, provides specific design guidance on commercial buildings and facades.
“The focus is on energy consumption and demand, visual and thermal comfort and CO2 emissions,” said Hitchcock. He said they would be looking into ways to enhance the glazing, framing and shading selections.
Mike Gainey, also of Azon USA, gave a presentation about the improvement of thermal performance in structural aluminum windows. He posed the question, “What does a thermal barrier do?” The answer: “It interrupts the heat transfer from hot to cold.” Gainey talked about the energy performance levels of using thermal barrier systems and how they can help greatly reduce energy costs and usage. He explained the window systems can be made more energy-efficient not only through the use of a thermal barrier as part of the aluminum frame, but also through the use of a warm-edge spacer in the insulating glass unit.
“The benefits are overall U-factor improvement,” Gainey said, adding that the key goal is also to minimize condensation as much as possible.
From Codes to Certification
Perilstein said it’s not that he’s opposed to the program itself. “A whole system calculation is a great design tool,” he said. “But it all goes downhill being attached to the certification and rating aspect [because of the costs involved].”
In ending his presentation, Perilstein encouraged industry members to speak up and get involved. “It’s been a challenge to get people to come to the NFRC meetings,” he said.
That’s a challenge GANA hasn’t faced. As executive director Bill Yanek noted, “GlassFab delivered on its goal of providing top-notch glazing education to industry newcomers and veterans alike. GANA is always striving to make its meetings better, and GlassFab 2008 was no exception.”
Megan Headley is editor, Ellen Rogers is contributing editor, Drew Vass is assistant editor and Debra Levy is publisher of USGlass magazine.