Sorry for the wait, but here's a short how-to on flintknapping. Knapping has been described as making little rocks out of big rocks, and there's some truth to that. Making the little rocks look the way you want, though, takes some understanding of the way rock breaks and how you can control that.
Not all rocks are created equal. We need rocks that are glass-like: rocks that are homogenous, grain-free, and have a high silica content. They also need to fracture conchoidally (that means the breaks are shell shaped). A few of the good knapping materials are flint, chert, chalcedony, some jaspers, and some quartzites. There's also obsidian (glass produced by volcanic activity) and of course, glass.
Here's our victim: this is a piece of Knife River Flint from North Dakota. Most of you folks are probably most interested in making arrowpoints. I'll start with something fairly large (a knife blade) because it's a lot easier to observe the process on a large piece. To make an arrowpoint you'd use the same basic process but on a much smaller scale. I'll try to show that later.
There are two basic ways to knap. One is percussion, where you strike the edge of the stone to break off flakes. This is generally the "rough" work to thin and shape a large rock. Controlled percussion can be used to nearly finish a piece. These are the tools I'll use to percussion that piece of Knife River. There's a billet (what I strike the stone with): it's a 5" rod of solid copper, 1" in diameter. Copper is soft enough that it deforms slightly and "grabs" the edge of the stone. Steel and iron are too hard. Other materials that are used for percussion include large antlers, dense sandstone, and some super-dense hardwoods. I typically use copper: it's cheap, readily available, gives very predictable results, and lasts a long time. The other things work very well, too.
There are a couple of grinding stones in the photo. The coarse grit is used for rough work: the fine grit is used for more precise work. You can't overestimate the importance of grinding stones. You use them to abrade and dull the place on the edge where you're going to hit. That allows the energy from the billet swing to travel into the stone, releasing the intended flake. Otherwise, the edge of the stone would shatter into tiny fragments.
Don't overlook the leather pad. You'll need something like that to protect your leg during percussion.
I don't want to jump too far ahead, but I'll go ahead and mention it. The other main knapping technique is pressure flaking, where you place a tool against the edge and press to remove flakes. Here's a pic of those tools:
The grinder is there again, joined by a long pressure flaker which is usually called an "Ishi stick." Ishi used a long wooden stick tipped with a horseshoe nail to pressure flake. This one is made of a 3/4" Delrin rod and tipped with 3/16" copper. The rectangular block is a hand pad to protect your palm. It's a piece of maple glued to a bit of dense rubber. Conveyor belt works great, too. Later on there'll be pics of how these tools are used.
One of the first things we need to do is look at the rock. Look for obvious problems like cracks or other potential problems (crystal pockets, fossils, limestone inlusions, etc.). Try to envision the finished piece in the stone so that you can get the most out of the rock.
Knapping is all about angles. You'll hear knappers yak a lot about convexities and concavities. Simply said, flakes need convexity to travel. Concavity will stop a flake short. That can lead to all kinds of problems. As you're looking over your rock, look for those angles and be aware of them as you knap. Now let's get started on that sweet piece of rock!
Here's how I hold the rock. Being righthanded, the rock is in my left hand, and that hand is anchored on my left leg (note the leather leg pad!) I try to keep the rock still -- no moving targets. Make a controlled swing. Even though it's a piece of rock, good knapping stone is brittle and will break very easily if you hit it in the right place. You don't have to swing like you're trying to put it over the left field fence.
Note that it's the EDGE of the stone that's struck -- not someplace out in the middle. We're breaking flakes off and they start at the edge. The flakes come off the underside of the rock.
In this pic, I'm pointing at the place I want to hit. That's called the platform. A flake will detach from that point and follow a convexity.
Now grind the platform so that it absorbs the energy from the billet strike.
Topic: Flintknapping Tutorial (Read 4031 times)
