There are four basic techniques that have been employed in the manufacture of stone tools. These four techniques are:
The following sections will explain each of these techniques in turn.
Hammer and Anvil Technique
The hammer and anvil technique for removing flakes from a core is perhaps one of the oldest documented methods. It is quite effective for making large flakes for direct use as tools, or for use as blanks from which shaped tools can be made. This technique entails using the core as a hammer, and striking the edge of the core against a large, stationary rock (the anvil) in order to remove a flake.
There are a number of disadvantages to the technique, however. The principal disadvantage is that the flintknapper does not have a great deal of control over the flake removal process. A second disadvantage is that the flakes removed in this manner fly up and away from the anvil, becoming very dangerous projectiles for anyone standing nearby.
The bipolar technique is a modification of the hammer and anvil technique. In bipolar flaking, the core is placed on the anvil for support, and then struck with a large heavy hammer. The compression from both ends of the core cause it to shatter into hundreds of flakes, some of which will be large enough, and of the right shape for use as tools. This technique is often found in areas where the only reliable source of workable stone is rounded river cobbles that are extremely hard to work in any other fashion.
The principal disadvantages to the bipolar technique are that there is very little control over the flake making process, and it wastes a great deal of raw material to get a few usable flakes.
Hard Hammer Percussion Technique
Both of the techniques already discussed depend on percussion to remove a flake from a core. Hard hammer percussion, as the name implies, relies on the same principles, but provides more control over how the flake is detached. In hard hammer flaking, the core is held in one hand, and struck with a hammerstone. Technically, the hammerstone must be made of a material that is harder that the core material so that it does not shatter in the flintknapper's hands. By using hard hammer percussion, the experienced flintknapper has very good control over where the flake will be detached and the size of the flake.
Soft Hammer Percussion Technique
While both hard and soft hammer methods take advantage of the fact that cyrptocrystalline rocks all break according to the Hertzian Cone principle, soft hammer percussion adds an added dimension of control to the process. In soft hammer flaking, a hammer or baton of material softer that the core is used. This could be soft limestone, deer antler, bone, or hardwood. Striking the core with the baton initiates a fracture according to the cone principle, but the soft hammer material tends to catch the edge of the flake, allowing the experienced flintknapper to actually help pull the flake off of the core. This works because the stone is actually shearing or tearing, rather than shattering, so it is a controlled breakage process.
Pressure Flaking Technique
Pressure flaking is used for the final trimming and sharpening of the edges of stone tools. It is also often the method employed to sharpen tools during their use-life. Generally, pressure flaking is done with a durable, flexible tool such as a piece of antler tine. The technique takes advantage of the elasticity of the stone to actually peel thin flakes off of the core material. The more elastic the material, the better it is for pressure flaking. Thus, the finest examples of long, thin pressure flakes come from obsidian specimens.