Passing insulating glass (IG) certification testing continues to be more challenging—now more than ever. Quality employees were lost, along with the knowledge and work ethic they possessed. So, as a consequence, the quality of workmanship on the plant floor has taken a hit. Now it’s more important than ever to maintain the highest degree of sealant to glass adhesion to increase your chances of passing. Indeed, proper adhesion is the name of the game!

The gas retention portion of the IG certification test is the most challenging portion and lately I am seeing it as the main cause of failure for window and IG fabricators failing to pass certification. The IG units must average 90% fill rate at the beginning of the test and 80% after enduring a rigorous series of weather cycling procedures. It really is a tough test and allows very little room for error.

Ask a physicist what happens when you trap 90 to 100% concentration of Argon in a confined space when the concentration of this gas outside of the IG unit is only 0.932% in the air, and they will tell you that there is a very high driving force for argon to try to escape the unit. It seems that mother nature loves everything to be in equilibrium. Therefore, due to this nearly 100 to 1 difference in the concentration of argon inside the IG unit (IGU) versus outside (in the air), Argon desperately wants to escape your IGU and it will find the path of least resistance to do so in its quest to achieve equilibrium.

So, exactly what is the path of least resistance? It can be anywhere along the bond line between your IG sealant and the glass, otherwise known as “the bond line interface,” where sealant to glass adhesion is less than perfect.

What factors lead to less than perfect adhesion?

Failure to efficiently clean your glass: Check the efficiency of your glass washer, water temperature, water quality and the effectiveness of your detergent.

Failure to properly edge delete your glass: IG sealants are designed to adhere to glass and not specifically to low-E coatings, of which there are many. In fact, the protective coatings applied to low-E products are specifically designed to be non-reactive (non-corrosive), which naturally makes it more challenging for a sealant chemist to design a sealant that will effectively bond to them with long-term adhesion as the outcome.

Failure to choose the proper IG sealant: All IG sealants come in 55-gallon drums, and the sealant is either black or gray. All IG sealants may look the same when they are coming out of the handgun or extruder, but as a polymer chemist, I can assure you that not all IG sealants are created equal. The actual blend of polymers, adhesion promoters and UV degradation inhibitors formulated into a high-performance IG sealant will tell the tale when it comes to their ability to stand up under extreme testing and field conditions which may be encountered. So, choose your IG sealant very carefully.

Failure to consistently employ a high degree of quality workmanship practices: One can deal with field failures by simply sending a replacement unit, but when it comes to passing IG certification, a single failed IGU can sink the whole test, causing you to fail and leaving you to repeat the whole test while incurring thousands of dollars in additional expenses. Automated sealant gunning systems can go a long way to ensuring proper and consistent gunning techniques and can be especially beneficial in the face of difficulties in maintaining a quality and consistent manufacturing crew. In the absence of automation, strict adherence to sound workmanship practices becomes even more critical.

So, there you have it. Ensuring you have these bases covered is necessary to fabricate high quality IGUs that will pass certification testing and maintain the best field performance. Make sure that you have these bases covered to give yourself the best shot at passing. It can have far-reaching consequences on your company’s success in the marketplace.

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