93. How do I test my Insulated BiltBest windows for fogging to see if they have seal failure?

Insulated glass consists of two or more pieces of glass that are bonded to, yet separated from, one another by a spacer bar. The space between the glass panes is an insulator by virtue of “dead air space”. This fabricated glass sandwich is glued together with sealants designed to keep the glass together and moisture out. The spacer contains a desiccant that removes moisture that might be residual from actual manufacture. Insulated glass seal failure occurs when moisture penetrates the edge seals and wets, or condensates within the air space.

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Despite a respectable track record for insulated glass naturally, there are failures. A moderate insulated glass seal failure will look like a cloud of moisture that has condensed on one of the inner surfaces of the glass in the airspace. It might come and go depending on the outside temperature, actual humidity, and even barometric pressure when added to the mix. This failure is also called “fogging glass”, “foggy window” or “window condensation between panes.”

A serious seal/glass failure will involve the permanent presence of moisture in the airspace. The worst IG seal failures usually involve the degradation of the spacer. Sometimes the spacer corrodes or even rusts. Sometimes the desiccant becomes so saturated that it turns to mush and becomes visible on the spacer. We often see failures in which, upon deglazing, one lite of glass completely separates from the spacer bar.