[CrazyGoat]

I was searching for a vid where they are doing a glass drying under vacuum and you can see how the condensation goes away when vacuum is activated, and they day sl, they say: "do you see how it sucks the condensation" while that happens, but I don't find it.
Anyway I like the idea of whom says you don't see the condensation from the inside the glass.
Thank you for your replies to this.
May you take a look to another question I posted and may be answer some of the questions I did?
https://www.chemicalforums.com/index.php?topic=103908.msg366062#msg366062
Thank you very much.

[kriggy]

The vapor from the flame condenses on the cold part of the flask, if you try this with a mirror you will se the same effect. If you use a heating gun, wich does not give any water from combustion, you will not have this effect.

That indeed might be true but how do you explain my observation: When flame drying a flast while it is connected to vacuum, the vapor is seen only one the first or second flame drying runs which include cooling down the flask to room temperature before heating again?

[rolnor]

Try this with a heatinggun, do you see any moisture?