What are some materials that allow air to pass but not, or to a lesser extent, water vapor?
Here are two materials I am aware of:
- Teflon is a material that allows water vapor to pass, but not air. Water itself can't pass.
What are some other sourceable substances which have this feature? What are some defining terms and measurements used to identify this property in a material, and how can the rate of water vapor / air transfer be manipulated in such a substance?