Heat Treating Rocks

Norway is full of rocks, but very few of them have any particular value in knapping. Flint is only occationally found on the southern coast in small pebbles and rhylite in one location in the west. Quartzite is too hard, quartz breaks a little irregularly and lots of others are more or less useful.

I had heard that quartz responds to heat treating, so I decided to test high grade quartz, quartzite and something that resembles metabasalt. The flakes, no more than an inch thick, were buried a few centimetres below the surface. A small fire was made on top and maintained for between 1 and 2 hours.














I then brushed the coals aside and let the ground cool for a little while. My immediate reaction when digging up the flakes were that the pieces of quartz seemed more shiny and glossy. There was no visible difference on the quartzite and metabasalt.














When testing the pieces I found that the quartz knapped much easier. The flakes travelled easier and didn't step in the regular fashion. It also felt sharper. On the quartzite, which supposedly doesn't respond to heat treating I found a small positive change, although it may be just my bias. The metabasalt just became more brittle and crumbled under any flaking.

I didn't expect any change during such a short time of exposure to such relatively small temperatures. As the results were quite pleasing, I'm not sure much more would be recommended with the quartz, since it may become too brittle, but it may be worth experimenting with higher temperatures and/or longer time in the ground with quartzite.

Arrowheads

I have a ton of projects going on now. Among them a fish trap, which will hopefully be finished by the end of this week. But I'm also working on a construction site these days. There is some slack during the day, while waiting for supplies and stuff. That is an excellent opportunity to knap a little. The two to the left have been made at work last week. The two right ones are made from some kind of English flint. The left one from Knife River flint, most graciously given me by Eskimoboy on paleoplanet.

Ground Stone Axe Update

How long grinding the edge of a stone axe takes is to a great degree determined by the quality of your abrading stone. Mine happens to be very good, so the process is quite fast. When I abrade edges on stone, I usually start by making a "half" bevel. That is, I start grinding the sides first, more or less to the angle I want the bit of the axe go at in the end.














When I have done that I start grinding much more steeply to even out any dips in the front. In this particular piece there was a rather deep flake scar in the front from testing the blank's integrity.














When the edge is totally even, the most timeconsuming part begins. Narrowing the bit to a usable bevel takes quite a while. Work systematically and if unmotivated, take a look on the progress. I think you'll be surprised of how quick it really is. I used only about 1,5 hours on the bit of this particular axe.














The last task on this piece is to make the handle. A task I fear will take longer than all of the stonework combined.

Drill Update

Being able to drill holes is not neccesarily essential in primitive skills, but it makes life a lot easier. The drill bit can mounted on a hand drill, bow drill or pump drill. The hand drill is the simplest and to me seems easier on the bits than bow drill since there isn't as much sideways torque. The bit can be a simple pointed stone or even bone or antler, but I feel knapped stone has a better combination between stability and hardness than the other alternatives. Storm uses quartz chrystals, which are potentially an even better material, but I unfortunately don't have any available to me at this time.

Knapping the bit

To understand knapping, you need to understand how stone breaks. The force of the blow is distrbuted in a conical shape beneath the blow. A cone itself isn't very useful, but when you understand that this is the way the force from the hammer (either stone, antler or hard wood) goes you know that you will need to tilt the core away from the direction of the blow to achieve a flake instead. The angle is different for the different hammer materials used. The drawing shows hammerstone striking off a flake at left, in the middle working the flake with an antler billet, upper right shows the principle of abrading the edges, lower right shows pressure flaking.







This is the principle of all knapping, but with fine pressure flaking you need to press more in the direction of the flake because the force is less sudden and the force travels in a more delayed fashion. This is a function both of the material used (antler) and the speed of application. Below I am using an elk (moose) antler billet to strike off a flake.














If the force isn't sufficient to fully free the flake from the core, you will end up with step fractures. They are abrupt changes in direction of the break and chances are, unless you strike off a very thick flake and thereby removing the step, every succeeding flake will end in that step, in effect reinforcing the step in every removal. The easiest remedy for a serious step is usually to attack it from a different angle, either from the the opposite end or from one of the sides.

When knapping, thinking in stages is quite recommendable, but I often mix them a little as suits me best. The first stage after the flake removal is to make the flake regular and thin it. This is usually done by using a soft hammer, like an antler billet. On smaller pieces you may do it by pressure flaking. Below: Pressure flaking in my own hazardous way.














When the perform is finished, you can start shaping the piece by pressure flaking. By putting a lot of pressure on the edge quite parallell to the flake itself, you will further thin the blank. This is not always what is wanted however, especially in the last phases of the knapping where you may want to strenghten the edge instead of thinning it. To achieve that use more sideways instead of parallell pressure. To be able to apply enough pressure to press off good sized flakes and to have strong enough platforms for striking of blades you will often need to abrade the edges to strengthen them.

Safety isn't my strong point to be honest, but since the flakes are horribly sharp it should be taken into consideration. I don't use googles, where would I get those in the wild? But by pressure flaking towards your palm (pad it with leather) or a hard surface the flakes will more than likely not hit your eyes. Being of a rather lazy nature, I often take a shortcut on this and pressure flake with my index finger and thumb pinch. If you don't take care that can cause flakes to fly in your face. If you get a small flake in you eye, it can usually be removed by blinking under water. But by all means, be careful. The photo shows the safer way of pressure flaking.














This drill bit is now finished and ready to be hafted. These instructions can be applied to most knapping and certainly arrowheads. Sorry the poor quality of the photo.

Ground Stone Axe Update

Though I have come to be very fond of antler axes, I like stone axes too. The advantages with ground stone over antler is, though not much sharper, it holds it's edge better. In comparison to flaked axes the edge is more stable and unlikely to chip unless you hit a stone or something.

I have made two of these axe (celt) heads before. One was hafted and tested and it definately worked very well. The second one still needs to be hafted. On this photo that particular head is found on the far right, the pecking stone (previously a hand axe from quartzite) to the left and the head in progress in the middle.














River cobbles often provide a minimum of work to make an axe. The one in centre on this photo has been integrity tested by chipping off a little piece in the front. Good axe stone is homogenous and hard.














The first stage in producing an axe head is to peck it down to the approximate shape. Be careful on the edge, not to chip the stone. The sharper a piece you use as a pecking stone, the more precise you can do the pecking and it is also faster. The next phase on making this axe is to grind the edge of the head sharp. By the way, I don't usually peck stone in the bedroom, this photo is staged. ;-)