Membrane formation

[berkan]

Hello, I am searching information for the process of membrane formation.
There is a method called DROPPING METHOD. and there are three subs like simple dropping, concentric dropping and air knife dropping.

Do you know how this methods work? I could not find information about these on the internet, I dont have a book as a resource.
I need to understand it, what is your suggestions?

Thanks a lot
Berkan