Too fast, the silk breaks, too slow, it sticks to itself and becomes tangled. Thus silk reeling movements are continuous, cyclic, spiralling patterns performed at constant speed with the "light touch" of drawing silk. Silk reeling is trained in solo forms and stances as well as in pushing hands with a partner.
As described by Wu Kung-tsao:
Two complementary terms, Chán sī jīng (纏絲精) and Chán sī gōng (纏絲功) refer respectively to Silk-reeling energy and Silk-reeling force. These terms are often used in English interchangeably (and incorrectly). Chán sī jīng refers to the energy that is built up in the body through the practice of correct Taijiquan, while Chán sī gōng refers to the practical outward effect of that energy.
Chen-style silk reeling movements originate from the dantian and trace a taijitu pattern. Starting first with the outside circle and then adding the "tear shapes" (to quickly change direction while maintaining a smooth motion) while shifting the thrust from leg to leg; this motion in turn drives the rest of the joints of the body in a fluid, spiralling motion.