As I travel to visit customers, I often get the frequent question, “What is the secret to passing insulating glass (IG) certification?” Indeed many window and glass fabricators have a tough time passing ASTM E-2190 and, for some, it takes several tries to obtain certification, which is a critical requirement in today’s fenestration marketplace.

When visiting an IG fabricator, the first thing I do is inspect and analyze their insulating glass fabrication process. I oftentimes see quality problems in their IG fabrication process that may end up being critical factors when it comes to passing IG certification. As I point these out, I sometimes hear remarks such as, “We have always done it this way, and we don’t have very many field complaints.” I can not stress enough that little things that may not always end up resulting in field complaints can still be a knockout factor when it comes to passing IG certification. This test is tough!

One of the most basic factors when it comes to making quality IG, regardless of the system employed, is proper glass washing. I see washers operating with cold water, poor water quality or improper rinsing. It is very simple. If you don’t start with clean, dry glass, then sealants and adhesives cannot create a lasting bond! They are designed to stick to clean glass – not dirt and contaminants. Upon initial inspection, it may “look” like you have a good bond, but when you send IG units to the test lab these units will be subjected to 15 weeks of intense weather cycling, which is designed to simulate the worst that the world can dish out to an IG unit. If there are any flaws in the system, even minute ones – failure will result! The worse part of it all is that if you fail the IG certification test, you go have to get back in line, pay your fee again, and start all over again! If you keep trying and still cannot pass, your IG certification can be revoked – Do not pass go! Do not collect $200!

Other basic things to consider when it comes to passing this test it to use a quality IG sealant and desiccation components. Oftentimes, the highest quality IG is not the most inexpensive! That does not mean that you cannot obtain a quality sealant at a competitive price, but don’t choose a sealant on cost alone. Sure, due to competitive pressure, all manufacturers are looking at ways to cut costs, but IG sealant is a critical material that can break your company’s back if it is not performing properly. The sealant or sealants, depending upon whether a single-seal or dual-seal system is utilized, are responsible for bonding the IG system together while limiting the amount of moisture vapor that enters the inside air space. The desiccant system adsorbs the moisture once it does get inside. Tiny flaws in the system will let in more moisture vapor and this is where a superior desiccation system ultimately may make the difference between success and failure!

Gas retention is another critical element of the test. The units submitted must average a minimum of 90 percent gas fill when the test lab receives them, and they must average no less than 80 percent gas fill upon completion of the test. In this regard, proper workmanship practices are an absolute must! Sealants must be applied in such a manner to achieve a uniform and dense barrier or gas leakage will occur at many times the amount as indicated by the sealant’s gas permeation rating. This may lead to a failure as it relates to the gas content portion of the test. The manufacturer may still pass IG certification but the thermal values listed on the NFRC label will have to be indicative of a non-gas-filled unit, which could put the window fabricator at a competitive disadvantage!

So for manufacturers who have not yet submitted test units, take one last hard look at your fabrication process before the day of truth arrives. Call upon your IG component suppliers to visit. Many offer quality audits as a service to help you build the best IG units that you can build. After all, your success is their success.

A fresh set of eyes can oftentimes notice something that you may have missed!


  1. Jim raises a lot of good points. Getting certified is not a slam-dunk. Most components are certainly designed to pass the test – but following proper procedures is paramount. There are always trade-offs in each of the components selected and the fabricator needs to learn about these differences, which are often not fully understood.. IGMA studies have often concluded that workmanship and following proper manufacturing procedures are keys to producing a long lasting (or certifiable) IG unit. IGMA is often a good resource for figuring out the answers to many questions.

  2. I was expecting more reaction and conversation to Mr. Plavecskys’ article. IGMA certification is a steep climb. The companies one would expect to have a hard time seem to pass and those fabricators that seem to exhibit a lot of sophistication seem to have re-test multiple times to pass.
    I also know a lot of people question the relevance of the rigorous test standard to the broadest market for IG…particularly in the US. Perhaps this isnt the proper forum to fight that battle over again but if the IG testing failure issue is still alive the relevance of the spec should be open for discussion. Maybe we can start a tempest in an IG unit?

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