Much previous work has applied mass-spring systems to individual hairs. One of the first approaches was Rosenblum et al. [1991],which used a linear spring for stretch and an angular spring between segments for bend. Petrovic et at. [2005] used a mass-spring system for simulating the dynamics of keyhairs that represent multiple rendered hairs. Selle et al. [2008] presented a mass-spring model for simulating all individual hairs. They used separate edge, bend, twist, and altitude springs to form an implied tetrahedron of springs between points, preventing volume collapse. Similar to these methods, we use a linear spring for stretch. Our hair model differs with the usage of two additional springs, designed to give our artists the visual look described in Section 1. We add a single spring for controlling bend, using the stably generated frame discussed above for the hair orientation. We define an additional spring to control the longitudinal stretch of curls during motion, not present in prior models.