Triskadecamus
The water and tea are not physical structures, and pass freely through the paper.
Surely you jest!
As you pour the water in the teabag is sealed by it before the air gets out.
My answer ,and it works for me, is to pour a little hot water into the cup first to warm it,tip that away, fill it boiling water again and steadily lower the teabag in.
If you put the teabag in very near boiling water the teabag floats up ,maybe steam bubbles form inside the bag and part inflates it.
Please report back on your experiments as this is a crucial matter to all us Brits 