On 10-Mar-2006, "RichK" wrote:

In addition, I wonder how long the gas stays trapped between the two sheets
of glass. And how do you know when it escapes.

The gas should stay for the life of the window. If it leaks, there will be condensation
between the panes as humid air replaces the argon. You will likely only notice
the condensation as the weather gets cold.

Mike