Monosteel blades are usually harder to sharpen and thinner than laminated blades. Digital filters are used to blur and sharpen digital images. The hardened bronze can then be ground to sharpen it to make edged tools. Professionals are also employed to sharpen blades to individual requirements. They must also grind, sharpen, and polish the blades. There are many opportunities for students to sharpen their leadership skills. Volunteer work has allowed women to sharpen leadership and organizational skills. Charles uses his hunting knife to sharpen the ends of long branches to make spears. He then goes upstairs to sharpen his knife. Hippo teeth sharpen themselves as they grind together. There were also six copper bowls and a pebble used to sharpen knives. This also makes them quicker to sharpen. They may sharpen it or harden it using other items. Additionally, such periodic scratching serves to clean and sharpen their claws. To ingest calcium and sharpen incisors, they often gnaw on bones.