Answered by Sidi Moustafa Elqabbany
What is the definition of washing in wudu’? does water have to drip from skin after contact, or mere contact would suffice?

Washing one’s face is accomplished by allowing water to flow over the entire face. It is not a condition that the water actually drip from the washed skin. However, mere contact with moisture is not sufficient.
The above applies to all the limbs of wudu, not just the face.
Mote details are mentioned here: Definition of a Washing
And Allah the Exalted knows best.
Moustafa Elqabbany
Metro Vancouver, Canada