Torsion as a method of achieving hemostasis is accomplished by seizing and twisting the proximal end of a severed artery until its resistance is completely overcome.  This is best done by grasping the vessel about half an inch from its severed end with a second set of forceps to stabilize it during the continuance of the twisting process.  Ideally, a forceps a trifle longer in the jaw than the width of the flattened vessel being preferred.  More frequently, slide-catch forceps are used as forcipressure instruments to achieve hemostasis.