Implicit surfaces are well suited to modelling organic forms that consist of an internal skeleton and deformable flesh smoothly blended around it. An implicit surface can represent such an object's geometric “skin” that deforms according to the motion of the skeleton. We propose a new, simple and efficient method for calculating local deformations to be applied to implicit surfaces during collisions with other objects or between different parts of one object. We discuss applications of this method to deformable object simulation, character animation and interactive sculpture.