Introduction: Grime is a dirt shader for LightWave which gives objects a dirty, battered, tarnished or old look. It consists of two algorithms, Grime-Nurbs and Grime-Polys, both of which trace the object’s geometry and apply dirt into cracks, crevices, recesses and the like. Grime-Polys is also capable of changing the surface on protruding elements (e.g. of worn painted objects). In fact, both algorithms can do it, but with Grime-Nurbs a simple trick is necessary, as shown in the tutorial section.