^^ good information there. thanks.
i need to really locate a variety hammer stones. i'm not even exactly sure of what i'm currently using, i think it is quartz. i found it in my landscaping rocks, hah hah.
Different hammerstones react differently to different materials. Hard hammerstones that are overly slick could slip on the platform, whereas softer hammerstone, such as sandstone and limestone, may grab the platform better.
Also, people may know that heat treating stone will make stone more brittle. But, the inverse is true, as well. Natural stone can be overly "flexible" - the opposite of overly brittle.
The problem with hammerstone flaking overly flexible stone is that the stone might bend, rather than crack. And, if it cracks after bending, it will cause the break to go slightly haywire, and cause internal fracturing.
So, hammerstone thinning may not be good for all forms of flaking - especially if a person is dealing with high grade stone, that is flexible, rather than brittle. In such cases, indirect percussion might be optimal over hammerstones. This may well be seen in the prehistoric flaking of really high grade materials, that were raw.
So, in working with hammerstones, you have to think in terms of the material of the hammer versus the material of the stone being flaked. Some hammerstones are acutely hard, such as quartzite, or granite hammerstones. Other hammerstones are much softer, such as sandstone and limestone, hammerstones. Some stone being flaked is quite brittle, such as obsidian, or heat treated stone. Other stone being flaked can be quite flexible, such as certain types of raw fine grained stone. Brittle stone is generally easier to fracture than flexible stone.
If a hammerstone is overly hard, it may be more prone to producing a deep bulb in the impact site. If a hammerstone is soft, it may produce a more diffuse bulb, at the impact site. If you learn to vary technique, you can range through both types of hammerstones. But, you have to learn to compensate for the stone's hardness, or softness.
To the outsider, it may appear that hammerstone percussion involves greater force than antler/wood indirect percussion. But, this is not necessarily true. The force involved generally depends upon the weight of the percussor times the speed of the swing. For example, a one pound billet swung at five miles an hour does not generate the same force as a twenty pound billet swung ninety miles per hour.
The difference between indirect percussion, and direct percussion, relates to the force to shock ratio. By separating the flaking tool, from the percussing tool, a flintknapper can increase force, while reducing shock. In general, this distinguishes indirect percussion, from direct percussion. So, it is not accurate to say that one process produces more force than the other process. It would be accurate to say that one process is more prone to generating greater degrees of shock. And, that process would be direct percussion. In some cases, this is good. But, it is not good in every case. There are cases when greater shock can damage the stone - especially if the stone bends, before the break begins.
That being said, how would one know when to switch from direct percussion, to indirect percussion? Ah, that is a good question. I think that the simple answer is that one can continue with hammerstone reduction, until it becomes apparent that the hammerstone work is damaging the biface. In other words, if the hammerstone work begins to produce internal fracturing in the edges, then one can always switch to indirect percussion.
But, here is the problem with focusing on making points from "start to finish" via authentic aboriginal flintknapping practices: Suppose it takes a fellow three to six months of near daily practice to develop good hammerstone skills, then what will happen if he focuses on other stages, while working to the finish, on every point? He will lose time on developing his hammerstone skills. Then, it will take even longer to develop good hammerstone skills.
Since many people try using hammerstones, and then quit, I would advise using hammerstones, while making bifaces for weeks, and months, and piling the bifaces up. As the skill level increases, some of the bifaces can be re-worked. When the skill level gets really good, the knapper should be able to throw coast to coast, and outrepasse, from time to time. Then, once the bifaces have accumulated, and the knapper has developed good skill, he can go back, and rework with other flintknapping processes. In terms of aboriginal flaking, I think that it is critical for people to get past this stage. And, it takes a lot of practice - maybe weeks or months of practice.
