Sorry for the delay since the last blog post. Non-procrastination on the thesis (yay!) has equated to procrastination on the blog (boo, I guess). But I’ve had enough of writing about gravel and fish bones for a bit, so I figured a little microblade break (with minimal latinate jargon) might be in order.
As I mentioned in the last blog post, slotted points with inset microblades should provide a suite of benefits over their bifacial counterparts. The inset points should be more durable and more lethal, making them preferable in high-risk hunting situations. At this point, these seem like null hypotheses to me: how can the inset points be anything but better? Nonetheless, when I actually hafted a few of the points and prepared to impale a few proxy animals, I had a niggling lump of doubt sitting in the back of my mind.
There was no need to worry. The inset microblade points not only performed admirably, but exceeded all of my expectations!
I conducted two experiments, both using blocks of ballistics gel instead of live animal targets. The ballistics gel is basically a super-high-grade pork gelatin that, when mixed to very exacting specifications, mimics the density and structure of mammalian flesh and organs with a high degree of accuracy. The FBI, UN, RCMP and other such organizations use it to analyze ballistics data such as bullet trajectories, ammunition types, etc. etc. The Mythbusters also use it whenever they want to find out whether something is likely to produce deadly wounds. There are also a series of interesting posts on Elfshot , a fascinating archaeology/flintknapping blog frequent, where Tim Rast used gelatin to experiment with Dorset toggling harpoons. Like the Elfshot experiments, I would be hafting my points to a spear and stabbing the blocks, but rather than examining the holding power of the point (my slotted points are not harpoons and should not hold), I would be looking at the durability of the point and inset microblades, and the wound created by it.
The first experiment addressed the wound channel. My basic hypothesis is that (1) because inset slotted points have very long cutting edges from the serial inset microblades and (2) because the antler could be shaped to make a broad point without sacrificing length or blade edge angle acuity, the inset slotted points would cause significantly greater internal damage to an animal than bifacially knapped points. To test this I set up a guide for my spear above a 20lb gel block, pointed a video camera at it, and briskly stabbed the block. The camera captured the point going in and the wound channel spreading out. Then the camera ran out of batteries, so I busted out the still camera.
I only made two blocks for this round of tests, but the results were still pretty compelling. The inset slotted points slice and tear through the (simulated) flesh, leaving a wide, ragged looking wound behind, a fair bit wider than the point itself. I was initially worried that this was the result of the block splitting because of the thickness of the haft and spear (3/4″ dowel), but a control test with a sharpened dowel showed that splitting gel follows a very different pattern. Also, the biface tests displayed a much more contained wound. The biface were sharp and penetrated at least as easily as the slotted point, but the wound never flared outwards, leaving a parallel-sided wound channel close in to the shaft of the spear.
The durability test also showed the awesomeness of the slotted points. I set a large bone (a beef metacarpal, I think- a big bone from the pet shop) in a gel block, placed it under the spear-o-matic, and attacked it vigorously. The biface snapped on the third impact with the bone. The slotted microblade points not only didn’t break, but only two microblades became dislodged from one of the points when it made a hard, glancing impact on the bone. The other slotted point kept all of its blades. Perhaps more impressive, the points and blades stayed intact for about 10-15 strikes each, and the weapon only failed when the spear foreshaft split lengthwise(!). I hafted the points in a 3/4″ hardwood dowel foreshaft with a spruce gum-filled socket, but next time I will likely try binding the points onto the foreshaft (a sort of side-haft) with sinew and hide glue. The gummy sockets were easy to set up and held the points well, but the splitting was suboptimal. A socketed bone or antler foreshaft would probably be ideal, but that will have to wait for a whole other round of experiments.
In any case, the results are looking pretty good at this point. More results will be reported when some of the deadline pressure has passed.