How a Sinker Forms a Loop

The knitting cycle in four moves

One knitting cycle has four recognisable stages. The needle rises to clearing height so the old loop slips behind the open latch. The yarn is laid in the hook by the yarn carrier. The needle descends, the old loop closes the latch, and the new loop is drawn through. The old loop is cast off. The sinker is active in the first and last of those stages.

What the sinker holds

As the needle rises, friction between the yarn and the needle tries to lift the old loop with it. The sinker nose comes forward and holds the fabric down so the loop stays where it is. Without that hold the loop rides up, the latch does not clear properly, and stitches are dropped.

Where loop length comes from

When the needle descends, the amount of yarn drawn into the new loop is set by how far the hook travels below the sinker belly. That distance is a function of cam setting and sinker geometry together. Change the sinker profile and you change the loop length for the same cam setting.

Why a worn sinker shows in the fabric

Wear rounds the nose and opens the throat. The hold weakens and the drawing point moves. Because sinkers wear at different rates around the ring, the fabric ends up with different loop lengths in different wales, which the eye reads as vertical lines.

What this means for ordering

Fit one complete set of the same profile per machine. Order against the reference on the old sinker plus machine builder, model, diameter and gauge, and change the set rather than individual pieces once wear is visible.