Most effective: Large, flat areas for example, the arms and legs. Least effective: Curved areas the same as the underarms, and probably do cause significant trauma for the face and also thin skinned areas. Always store your hair cutting tools in a salon shear case or holder. https://unique-pineapple-lknbkg.mystrikingly.com/blog/hair-care-problems-that-might-affect-your-overall-health