Plavecsky's Ponderings By Jim Plavecsky
by Jim Plavecsky
November 19th, 2020

Not Sure if Your IG Units Can Make the Grade? Just Dunk Them!

With skilled labor being such a big issue these days, window fabricators have lost some of their key people this year. Some were furloughed during plant shutdowns and never returned for a variety of reasons. So, one of the ugly things I have noticed this year is that it seems like there may be an increase in the number of window fabricators failing the insulating glass (IG) certification tests at labs, thereby necessitating retests. Could it be that the overall skill level is diminishing in your factory as tenured employees were lost and newer untrained employees came in to take their place?

ASTM E2190, which is the Certification and Testing for Insulating Glass Units, is not an easy test to pass. It is basically designed to expose the flaws in a sample group of insulating glass units (IGUs). These units go through rigorous testing, including 42 days of high humidity testing, plus 63 days of accelerated weather cycling. All of the units submitted must pass, so there can be no mistakes in the fabrication process.

The three basic components of an IGU are the spacer, the desiccant and the sealant. The spacer creates the air gap which provides the insulating effect. The desiccant absorbs moisture vapor that permeates into the air gap which can fog the unit, and the sealant does double duty. First, it holds the whole unit together over the course of daily expansion and contraction, which happens during the weather cycling portion of the test. Second, it impedes the entrance (permeation) of moisture vapor trying to get into the air gap while preventing the exit of gas that is contained inside the air gap. Some spacer systems, such as the flexible type, also contain an adhesive which bonds the spacer to the glass, thereby relieving the load placed upon the sealant to glass interface. In other words, it helps the sealant to do its job.

As you can see, the desiccant is like your safety on a football team. If the sealant becomes weak, usually due to poor sealant selection or improper workmanship, and allows too much moisture vapor into the IGU, then the safety stops the moisture vapor dead in its tracks by capturing it and locking it up so that it cannot create the fog which becomes an IGU failure. In a nutshell, you can get away with small flaws in the unit, and the safety will make the tackle. The unit can still make it through the test and pass.

This is not the case when it comes to argon retention. These days, in order to pass the test with argon certification, the argon units submitted must average 90% initially and 80% at the conclusion of the test. But if argon is moving through the sealant faster than it should, there is no safety on the outside of the unit to capture the gas, let alone to put it back into the unit. Once the argon slips out it’s lost forever and the IGU will not pass the argon certification portion of the test. Those little flaws have now become deal breakers.

So, if you have lost some of your key people and are facing an upcoming certification test, reach out to your IG component suppliers. They can conduct quality audits and help provide training exercises to help your IG fabricators understand what must be done to increase your odds for passing this demanding test. In addition to this, it is important to have your own in-house tests to evaluate IG quality on a daily basis.

Over the years, one simple in-house test that I have always recommended is the dunk tank. Having started my career as a polymer chemist working in the tire industry, we would take tires and dunk them into a hot water tank. Any flaws in the tire would show up quickly as bubbles would rise to the surface. This test, as simple as it is, can also be used as a quick test of the integrity of your IG units. Just grab some random samples off the IG line and dunk them in a hot water tank. As the air or argon gas heats up it will escape through the path of least resistance and you will see the flaws in your insulating glass units.

So, if you want a quick evaluation of your IG units, just “Dunk them!”



One comment
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  1. Good article. Need to do the “Dunk” more often .

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