This Global rough 120 grit ceramic whetstone is used when edges are chipped or damaged. When sharpening knives, scissors, planes, engraving tools, etc, it's most important to remember to maintain the same angle (degree). This applies whether one is using a ceramic whetstone or a honing rod. Apply a small amount of water to the surface. Then hold the knife so that the blade meets the face of the whetstone at an angle of 10deg-15deg. Sharpening instructions are included.