I've been looking around at replacement windows and have visited several showrooms.
One of the salesmen told me something that is making me think twice about Argon gas in my windows. He mentioned that the Argon in between the panes of glass leaks out gradually over time. This makes sense, since all seals leak to some degree.
Then he mentioned that as the gas goes out a vacuum forms causing the glass to bend inwards into a concave shape. He said you can see the distortion in many windows if you look. He also mentioned in very large windows the distortion is so great that the panes almost touch in the middle.
Then he went on to say windows filled with air use a capillary tube in them allow "pressure" to escape so they are less prone to this type of distortion.
Has anyone ever heard of this before?
Thanks for your help and time.