What sort of sound should you be looking for when you tap up a blade? (ither with mallet or finger)
Easiest way of explaining the sound thing is, using the drum analogy
If the skin on top is the pressing and the space below is the elasticity..
If the skin is just right you will hear a good deep tone and resonance, meaning you have a good stiff layer on top of the blade and good elasticity behind it
If you have a thick skin the tone will be muffled and little resonance
Hope that helps