Knapping is the shaping of flint, chert, obsidian, or other conchoidal fracturing stone through the process of lithic reduction to manufacture stone tools, strikers for flintlock firearms, or to produce flat-faced stones for building or facing walls, and flushwork decoration. The original Germanic term knopp meant to strike, shape, or work, so it could theoretically have referred equally well to making statues or dice. Modern usage is more specific, referring almost exclusively to the hand-tool pressure-flaking process pictured. It is distinguished from the more general verb "chip" (to break up into small pieces, or unintentionally break off a piece of something) and is different from "carve" (removing only part of a face), and "cleave" (breaking along a natural plane).
Lithic reduction
Flintknapping or knapping is done in a variety of ways depending on the purpose of the final product. For stone tools and flintlock strikers, chert is worked using a fabricator such as a hammerstone to remove lithic flakes from a nucleus or core of tool stone. Stone tools can then be further refined using wood, bone, and antler tools to perform pressure flaking.
For building work a hammer or pick is used to split chert nodules supported on the lap. Often the chert nodule will be split in half to create two cherts with a flat circular face for use in walls constructed of lime. More sophisticated knapping is employed to produce near-perfect cubes which are used as bricks.
There are many different methods of shaping stone into useful tools. Early knappers could have used simple hammers made of wood or antler to shape stone tools. The factors that contribute to the knapping results are varied, but the EPA (exterior platform angle) indeed influences many attributes, such as length, thickness and termination of flakes.
Hard hammer techniques are used to remove large flakes of stone. Early knappers and hobbyists replicating their methods often use cobbles of very hard stone, such as quartzite.