There’s still a chance that someday there will be an industry-wide standard for measuring optical distortion in heat-treated flat architectural glass. But from whom should such a standard come?

“My personal preference is to let the market dictate it,” says Chuck Wencl, the veteran heat treating process engineer for Viracon, who also chairs the Glass Association of North America’s (GANA) Optical Distortion Committee. “GANA’s not here to put people out of business with a mandate.”

Some within the glass community contend there should be an established standard before architects less willing to compromise impose one of their own. Others, like Wencl, however, prefer a more laissez-faire approach that mandates a standard if and only when absolutely necessary.

“Depending on the application, it could make a difference,” says Urmilla Sowell, the technical director for GANA.

The debate of sorts is, in many ways, a self-inflicted one that is a direct result of the public’s increased awareness. They do nothing to compromise the safety, strength or durability of glass, but distortions are the bane to architects and customers everywhere desiring to see an aesthetically-pleasing lite of glass in their projects.

It’s getting there that has been the sticking point.

Wencl says that the technologically advanced digital grid photography such as that used by his company is the best current way to measure the distortion in any glass, but the steep costs of the premiere variety of the machines exclude any likelihood that everybody in the industry would ever be forced to ever follow suit.

Mostly developed within the last five to 10 years following the advances in digital technology, the on-line digital grid photography machines provide a 3D picture of every square inch of a piece of glass, calculating what its surface will look like while also noting any possible deviations.

“I think anybody who has seen it or used it is very impressed by it,” Wencl says.

But not everybody can foot the hefty bill for that kind of technology. The machines typically run anywhere from $80,000 to $120,000 each, and added exorbitant costs come later in the form of repairs and upkeep.

“It works for us,” Wencl says. “It solved a lot of issues for us, but we can’t go out there and impose that on everybody. It costs a lot of money.”

More affordable off-line digital grid photography machines are available anywhere from $10,000 to $20,000, but they are nowhere as effective or as user-friendly as their on-line counterparts, Wencl says.

Either method is still a quantum leap forward for the industry, Wencl says. It wasn’t that long ago, he notes, that glaziers were still using flat-bottom gauges that required a person pushing a device across the glass to seek out any deviations before advancing to three-point gauges that first removed any human contact from the process.

The issue becomes even more pertinent each day with the advent of so many varying types of glazing systems, glass treatments and framing options, all of which could possibly leave unsightly distortions on glass.

“Architects are very picky,” Wencl says, “and they want glass to look just like it did when it was annealed.”

1 Comment

  1. Current standards (in USA or in Europe) are not demanding enough about glass flatness, after tempering, for large building facades
    I would recommend, for tempered glass, several classes with, for each class, a level of acceptable deformation

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