IGMA Debates Visual Quality of IGUs

By Megan Headley

The Insulating Glass Manufacturers Alliance (IGMA) visual quality working group discussed comments and intended to clear up its guidelines on visual quality of insulating glass units (IGUs) as IGMA opened its meeting today in Tampa, Fla.

In particular, the working group addressed comments that parts of section 4 of the document are too stringent. The section on conformance requirements lists visual obstructions that should not be allowed in an IGU including: adhesive residue, dessicant dusting, dirt/debris, fingerprints, fogging, suction/vacuum cup marks and water/cleaner spots. The document also states that marks on the flat glass used in the IGU should comply with ASTM C10-36 and sightline infringement shall be no greater than 1/8 inch along any sightline of the IGU.

"When you put out a document that says 'not allowed' … my concern is that we're going to be rejecting product that's perfectly sellable," said Jeff Haberer of Cardinal Glass Industries. "We're mandating perfection, and I think we need to scale it back here."

"In order to be practical, you have to allow certain imperfections," added Bill Hammon. "Minimizing is the key word."

Following discussion on what constitutes a visual obstruction and concerns of overstepping other documents on similar topics, including ASTM C10-36, the group agreed that many of these items should in fact be quantified. The group agreed only two items, fogging and suction/vacuum cup marks, should not be allowed in the document.
Several group members commented that the type and quality of the lighting can impact the visibility of an obstruction.

Chris Barry of Pilkington suggested the document state that standard lighting conditions be used to determine the visibility of an obstruction.

Bruce Virelson of PRC Desoto International reminded the group that fog is sensitive to lighting. "There have got to be some sort of comments in there on lighting," said Virelson.

However, others noted that lighting conditions can't necessarily be controlled in the field.
"If you're getting very prescriptive with the lighting, how are you going to meet that in the field?" asked Tracy Rogers of Edgetech.

The working group is now reviewing these comments.

The IGMA meeting continues through Saturday at the Renaissance Hotel Tampa International Plaza.

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