Preventing IG Failures
IGMA’s Educational Seminar Dissects a Hot Topic
by Alan B. Goldberg
Preventing insulating glass (IG) failures is a topic of constant concern for window manufacturers. To educate manufacturers, the Insulating Glass Manufacturers Alliance (IGMA) conducted an educational seminar on preventing IG failures, May 3-4, 2004 at the Woodfield Hyatt in Schaumburg, Ill. Opening the meeting, Bill Lingnell of Lingnell Consulting Services, spoke about the need to raise the bar on quality. The presentations by component manufacturers were aimed at doing just that.
In a brief overview, Randi Ernst, founder of FDR Design, emphasized the need for greater training, particularly with new people involved in the manufacture of insulating glass.
“We can’t expect (component) manufacturers to carry the burden of training,” he said.
Ernst reminded attendees of IGMA’s goal to certify 50 percent of the glass fabricators in North America to its standards for producing units (this is a voluntary certification program). He referred to the success of the Energy Star® program with consumers, even though it does not define durability.
“The government is looking to (the glass) industry to define itself, define durability and zero energy usage in a house, all of which impacts windows,” said Ernst.
Glass Washing and Cutting
Recommendations for glass washing and cutting were given by Mike Burk, productivity solutions manager for Glass Equipment Development. He advised manufacturers to get all suppliers involved with recommendations for the proper use of equipment and materials.
“It is up to you to identify compatibility issues such as adhesion, scratching, edge deletion, de-lamination, fogging, discoloration and spotting,” he said.
Regarding spray lubricants, he said they should not be used in the IG department.
“They do not go away,” said Burk. “They will affect adhesion and you will certainly have failures.”
He suggested the use of water-soluble cutting oils so they can be washed away. He urged the replacement of cutting wheels on a regular basis to avoid damage to the glass.
“The tendency is to use more pressure instead of replace-ment. Check for accurate cuts, dimensions and squareness or glass damage.”
Burk added that hot water (maximum 135 degrees F) should be used for glass washing and clear fresh water for the final rinse. He warned that glass coatings must be face up in a horizontal washer or face out on a vertical washer.
Jeff Haberer, who works in product development at Cardinal IG, discussed coated glass—types, handling, storage, cutting, washing and fabrication.
According to Haberer, coated glass must be stored in a clean, dry area at room temperature, with no high humidity, no truck exhaust, no acids or other chemicals and no direct sunlight. Clean, soft gloves must be used when handling glass and the coated surface must be kept away from conveyor rollers and harp rack separators. He said when cutting, the coated side must be up and the table surface must be clean. During glass washing, the wash water should be monitored for acidity and a pH of seven (or as close as possible) should be maintained.
“Do not allow glass to stop under the brushes or air knives,” he warned, “and, inspect the glass after each step.” He recommended fluorescent lights be placed 12 to 18 inches above the glass as it enters the glass washing machine.
The role of desiccants in IG units was outlined by Tom Dangieri, senior application specialist at UOP Molecular Sieves. Defining desiccant as a material with a high affinity for moisture, he explained their ability to remove moisture and solvent vapor after assembly of the unit. Dangieri covered many do’s and don’t s in handling, emphasizing the need to inspect for damage when desiccant is received and to avoid using a desiccant that has been damaged in transit or storage. He stressed the importance of selecting a desiccant based on a priority of needs—water capacity, solvent capacity, air and inert gas.
Denny Raske, director of international sales at Allmetal Inc., gave an overview on the types of spacer and muntin systems available. He explained the primary functions of spacers—to separate lites of glass, hold or carry desiccant, provide aesthetic value—and described the features of each type, including shape, height, substrate and finishes and colors. He also covered do’s and don’t s.
“Don’t allow burrs or high spots in the spacer especially in corners or bent spacers. Don’t use spacers with residual cutting oils, or plugged breather holes,” he said.
Muntin bars which are used to simulate divided lite windows and for security are available as flat, contour, extruded or pencil bars, in a variety of finishes. He told the audience to be sure to wear gloves to avoid contamination, and to minimize contact with the sealant and align muntin bars properly with the reference grid.
Why units are gas-filled, why argon gas is preferred, the mechanics of gas filling and how it works were explained and demonstrated by Ernst. He said it was the introduction of low-E coated glass and plastic film that made gas filling viable.
“Gas filling is a low-cost procedure that provides major improvement in the product’s thermal performance. Argon is the gas most frequently used because it is inexpensive and readily available.”
He pointed out that krypton, while more expensive, is impressive in glazing units where small thickness is of prime importance. Although energy savings is important, he said the real comfort benefit of gas filling is the increase in the inner glazing temperature which substantially reduces or even eliminates condensation on the glass.
Kristen Gray, sales manager in the window business unit at H.B. Fuller Co., described the function of the sealant, generic types of sealants used in insulating glass units, physical properties, quality control issues and the performance of IG units. She compared generic types of sealants based on ultraviolet resistance, heat resistance, cold-impact resistance, cohesive strength and solvent/plasticizer resistance. When selecting a sealant system, the following must be considered: physical and or barrier properties, ease of manufacturing, speed of manufacturing, cost and glazing.
“Defective glazing will cause premature failure of IG units,” said Werner Lichtenberger, special
projects manager at TruSeal Technologies, who reviewed glazing techniques. Glazing should be done at temperatures above 40 degrees F. Below this temperature, frost and condensation can contaminate the substrate. Surface preparation, or a clean surface, is necessary prior to glazing. Setting blocks should be neoprene or EPDM with a Shore A hardness of 80-90 durometer. Handle units carefully, he said, to avoid edge damage and possible stress cracks. Glazing tapes must be kept under proper compression, and vent to the exterior. The size, shape and position of the vent (weep) holes is critical. Lichtenberger also pointed out problems from window washing.
“Glass washers become glass contaminators when rinses don’t work,” he said. Detergent film on glass destroys the water resistance of the adhesive bond to the glass. Detergent contamination causes waterproofing sealants to fail, exposing weakened IG seals which will also fail prematurely.”
“I thought the presentations were very worthwhile,” said Patrick Mink of Pella Corp.
“I am new to insulating glass and I learned a lot from the detailed information that was given.”
“This was a good conference for me, having recently returned to an insulating glass operation,” said Jim Dotter of Hurd Millwork Co. “The presentations were an excellent refresher, particularly those that covered glass breakage, gas filling and sealants.
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