Re: [ATM] Does glass retain moisture?

["Vladimir Galogaza" <vladimir.galogaza@zg.tel.hr>]

Moisture ( water) consists of highly polar molecules
which are sticking to many substances, glass included,
as a film or monomolecular layer. It is not easy to get
rid of it.

I doubt that water molecules can penetrate glass in
anything more than surface bounded layer.

Hydrogen molecules are the smallest and most agile
in their thermal motion and therefore penetrate
many substances most easily and to considerable depth. Porosity
of Palladium membrane for hydrogen can be changed by
regulating its temperature. This is used to make
hydrogen valves for extremely fine and controllable flows.
It is used also to separate hydrogen from oxygen in 
hydrogen generators based on water electrolysis.
Hydrogen gets through but oxygen and water molecules don't.

High vacuum people are using glass windows for 
looking into vacuum chamber. If water molecules
will penetrate glass in amount sufficient to change its
volume by going into molecular structure, they will enter
the chamber, but before this will happened, smaller
molecules of gases in the air will penetrate faster.
I think that such leaks are not observed when glass is
concerned.
Therefore indirectly I doubt that there is anything real in
this thread hypothesis.

That star test of the very good mirror at high humidity is 
different from one at low humidity, as taken for granted
in the thread, must be confirmed ( referenced) and
must be separated from all other possible causes.
Otherwise it has equal weight as assumption that
summer days are longer than winter days because
everything expands with temperature.

Vladimir.

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