Learning

Students begin by learning how to perform a whole series of qigong/neigong exercises which lay the foundation for reeling silk.

Later, the same exercises are then reconsidered with a different emphasis.
Coordination and timing become the focus, as well as alignment.
By moving the body in an increasingly integrated manner, the strength increases and the correct muscles are used for the production of power.
Lines of force are critical at this stage. In particular the maxim: square on the inside, round on the outside.

This builds up a lot of physical power and every movement feels to come from the muscles of the central torso, back and legs.

Eventually, the exercises are re-considered.
Now that the correct alignment exists and the muscles are working effectively, the focus shifts to rhythm and flow.
Instead of feeling muscular, the muscularity has been internalised and can no longer be felt.
The kinetic wave is the onus.

Reeling silk skills will not emerge in the beginners syllabus.
It is only later when reeling silk becomes a neigong that the full power is apparent.
The graded student must master the exercises introduced in the beginners syllabus, for these hold the seeds of what is to come later.

A skilled student demonstrates reeling silk in every single movement.

A master internalises reeling silk until only the most subtle kinetic wave is left.
Be advised that reeling silk can never be completely internalised.
If you can see no evidence of it in somebody's tai chi, then it most likely does not exist.