If It Doesn't Stick
Chris Barry of Pilkington is considered by many to be the leading expert in the analysis of failed glass and failed insulating glass units. Chris was introduced during the technical presentation session at a past Insulating Glass Manufacturers Alliance meeting where he was scheduled to discuss adhesive failure of insulating glass units. After being introduced Chris said simply "If it doesn't stick, get out of town quick" and sat down. After the laughter quieted down, Chris resumed his presentation covering the failure of units due to the loss of adhesion between the glass and the sealant, or between the sealant and the spacer system.
Although Chris' quick statement brought laughter to the meeting, it's meaning hit home for those in the room. No matter which spacer system or sealant you choose to manufacture insulating glass, if the sealant or adhesive doesn't stick to the glass or the spacer, the unit will fail prematurely. "It doesn't stick" or maybe more scientifically stated, adhesive failure, can be caused by poor practices in the IG department. Contaminated surfaces are often the most common culprit.
Any adhesive or sealant that contacts debris will stick to the debris and not to the glass or spacer. Therefore, the glass must be completely clean as it exits the glass washer. Not partially clean, requiring a little spray of glass cleaner and some paper towels. The glass must be completely dry; this means no water, especially on the trailing edge. If the washer is not operating properly, shut it down and have it repaired. Any operator who attempts to spot clean or dry lites exiting the washer will only make matters worse. Inspect the glass prior to assembling the IG unit and develop standards that will identify unacceptable glass. Quality checks should address detergent compatibility, wash water temps, brush contact, rinse action, detergent residue and dryness.
The insulating glass assembly area and manufacturing equipment must be cleaned on a regular basis. The rollers, conveyors and assembly stations or any surface that contacts the glass or spacer system must be free of dust, dirt or debris. Vacuums with filters and clean, lint-free rags should be used to clean the equipment. The use of air hoses and brooms should be minimal to avoid spreading airborne contaminates.
The assemblers must be trained on adhesion requirements. This includes a review of the proper non-contaminating personal protective equipment. The operators need to understand possible implications caused by the use of aerosol paints, silicones or other lubricants. They must realize that food, lotions and hand cleaners are contaminants that could lead to unit failure.
The spacer systems, sealant and adhesives must be handled in accordance with the manufactures instructions. Excessive ambient exposure or surface contact by the material may reduce its adhesive capabilities and reduce the life of the insulating glass unit. Quality procedures should describe and document the requirements for storage conditions, shelf life, melt temperatures and required cure time. The adhesive test procedures defined by the product supplier must be conducted on a regular basis. These procedures should physically test for the required adhesion.
Reviewing these steps will ensure that you produce long-lasting, high-quality insulating glass units. You won't have to "get out of town quick" and your windows will continue to protect the view.