French doors and fog

[FreedomClean]

I'm not sure this is where this belongs, but I wanted the feedback of some of the window folks.
I recently cleaned a home here and part of the job was a set of French doors leading from the basement to a patio outside. The insides of the windows needed to be scraped because they had just been finished and the basement had just been finished so there was a lot of sheetrock dust, etc. No problem. I cleaned both sides of the windows with Windex and thought they looked great until I was walking away and noticed what I thought was a previously unseen smudge. I determined that it was on the outside and commenced to giving it another scrubbing. No matter which way I turned, I couldn't see it from the outside, but when I went inside, I could still see it. The size and shape hadn't changed at all and now it resembled more of a fog than a smudge. I never did get it off and the homeowner never said anything but now I'm intrigued. Can anybody shed any light on this?

[Grizzly]

Were they French style doors with the panes inside the glass or the panes outside of the glass?

Bill

[FreedomClean]

There were no panels. Each door was just straight glass. I'm wondering if it was just a defect in the glass, something that maybe allowed some moisture to get in between the glass...

[Grizzly]

If they panels are inside the glass, then the seal around the glass has failed and the argon gas has escaped allowing condensation inside the two panes. Show to the client as if these are new, they may want to redress the issue.

Bill