• Field Notes 07.02.2013

    In past blogs I’ve reflected on the use of glass in some very strange conditions:  the Willis (Sears) Tower observation booths, the bottom of a gondola on hot-air balloons, and the walkway over the Grand Canyon that allows a one-mile straight-down view. This amazing material our industry works with is remarkably adaptable to changing human needs.

    I’ve always been amazed at what architects ask us in the industry to do with glass, and our ability to innovate and deliver is remarkable. We now use glass in combination with other materials to protect people from fire, bomb blasts and hurricanes. All this from something that’s been around since the Mesopotamians came up with it (credited in 3500 BC). No other building material I can think of, except wood or stone, has been around as long. Artists also have used glass in everything from medieval rose windows in cathedrals to glass bowls that are almost 40 inches in diameter, according to Guinness.

    Glass can be tinted, filmed and used in a myriad of constructions:

    • By itself as “clear” glass (even that definition has changed, now a.k.a. low-iron glass);
    • Laminated with other lites;
    • Made into double- and triple-glazed units to provide wind, water and thermal protection; and
    • As a shading device (with frits and patterns).

    I could go on ad infinitum: it’s used as handrails, keeping occupants safely on balconies or overhangs; as a touch medium on smart phones and pads, etc.

    Adding to the wonders, glass keeps getting thinner, stronger and is asked to do more and more in the evolving tech world.

    I’m no engineer, but one of its fascinating characteristics is that regardless what you do to strengthen it, it deflects the same under load.  Annealed to heat-strengthened to tempered, the relative strength ratio is 1:2:4.  But under a uniform load and a constant thickness, the glass deflects the same. I don’t know of any other material that behaves that way. With any other material, if you strengthen it, it deflects less.

    Glass is heat-treated (heat-strengthened or tempered) for strength to meet several loading criteria. For thermal needs, primarily to be able to absorb direct sunlight, or because of other things done to the glass, such as tinting or filming. Thermal loading can come from adjacent, reflected loads, as well.  When reflective films are added to glass, and then placed on inside corners where direct and reflected sunlight can result in high loads, treating the glass to resist that load requires that it be strengthened.

    Its ability to absorb wind or impact loads also requires it to be heat–treated.  It serves double-duty in these instances: when tempered and used in doors, tempering can provide safety to users. And even here, there’s an alternative, but still that alternative involves glass: it can be laminated, instead.

    Bending, warping and forming glass into three-dimensional configurations is coming into vogue.

    So, amid all the concern about how people use glass in handrails, all the glass geeks out there looking at the glass, not through it, and the limits being put upon the architects to cut down on it, let’s not lose sight of the fact that, like wood and stone, glass has been successfully modified to do other things for us.

    I hope the public realizes, as the folks at the GANA’s Annual Conference recently learned, that glass is essential for human wellness. Namely, basking in sunlight directly affects our well being, yet since most of us are often indoors, we rely on glazing for access to full-spectrum light. We can’t all sit in the sun every day with one of those drinks with the tiny umbrellas in them, but instead have to work in what we tell our kids is the “real world.”

    In both our personal and professional lives, we obviously have a vested interest in making sure we do all we can to get smarter about how glass can and should be used. Hopefully, the storm clouds surrounding glass will motivate us all to do more with glass, not less.  I think we have a friend in the architects, as I don’t see them willingly accepting the efforts of those who would limit the use of glass.

    As the song says: “I can see clearly now, the rain is gone.”  The clouds may not be entirely gone, but here’s to more light and vision using glass. I’m betting on something that’s already been around for 5,500 years hanging on a lot longer.

    Posted by Blogger @ 7:39 am

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USGlass Magazine

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