Friday, February 22, 2013

Archaeology Test Kitchen's Turkey Surprise!

Hi all,

Click here for the video

Early attempts on left and later attempts on right
Here are the results of the antler inset with blades versus the obsidian Bonito Notched point.  I went to the market to purchase the most meat for the least price, turned out to be a slab of turkey breast that day.  So with target in hand I needed to set up a few more things.  I wanted to start assessing blood loss is some way or another so I rigged up a styrofoam cooler with water and stuck the turkey to that.  It's all still in R&D phase right now.  If you have any suggestions for mimicking blood pressure and hide tension send them my way and I'll make a mock up.

Righto! on to the test...

As usual I shot a cane arrow shaft (from last time) fletched with turkey feathers from a 45 lb recurve bow.  I used one Bonito point hafted to a foreshaft with pine pitch and deer sinew and one composite antler and blade point.

This is going to be awesome
A little about setting blades into antler.  It's not as easy as it looks in the archaeological illustrations.  You'll find that a lot of archaeological illustrations that intend to describe production chains are over simplified to such a degree that they are almost incorrect.  Perhaps this comes about as authors adapt images for their own papers and mess up the nuances.  In this case I needed a lot more pine pitch and the grooves needed to be way deeper than I originally imagined.

Isolated platforms over dorsal ridges
Additionally, those tiny little blades put up a fight and don't like to stay in the pitch.  I ended up roughing up the basal edge of the flakes to give more surface area for the pitch to adhere to.  Set them deep and use a healthy dose of pitch.  I found it helped to heat the pitch, set the blade, then reheat the blade to get it in further.

Regarding the microblades, uniformity is nice but by no means essential.  Now when I imply that a little variability is ok, we're still talking in millimeters.  I find that the most critical measure to control is flake thickness, as in the amount of space the blade needs between the edges of the slot you've cut.  I used an antler punch with indirect percussion at first but found the technique to make thicker blades than I needed.  I'll need to get better at that technique as I imagine it is totally possible to mass produce fantastically uniform flakes with this method.  Pressure flaking actually produced the thinnest, most uniform flakes in this test.  Platform preparation is key.  set high-angle, isolated platforms directly over your ridges.  Remember, the further back you place your pressure flaker the thicker the flake will be so keep things close to the edge of the core.  I also found it helpful to score a little notch on either side of the isolated platform with a chert flake.  A little cut on either side makes it easier to initiate flake detachment.  Another trick I've seen is to grind the entire top of the core on sandstone to break up the surface tension.  Doing this kept a uniform platform angle and actually made flake removal much easier. 

So how did it all work?
Composite left, Bonito right

Well...the Bonito point flew great and made lenticular holes in the meat.  I was able to make upwards of six successful hits before the point snapped.  The blades had to be replaced after every shot, some of which I dug out and refitted.  The Bonito point penetrated further than the composite tip, most likely due to lower friction as opposed to the massive surface area and resultant drag of composite weapons.  The composite point had issues with blades popping out but created massive tissue damage when things worked well.  The composite point created wound paths around 3x larger than the bifacial Bonito point, yet lost speed quicker once in the tissue.  So it's a trade off, massive tissue damage for shallower or a longer wound path with less trauma.  Anyone know of any studies that formulate some sort of tissue damage index? like surface area cut/distance traveled?

Sinew held but something had to give.

All in all an informative preliminary test of wound depth versus surface area damaged between composite and bifacial projectiles.  Hopefully we can do a test with actual numbers soon.  This will all be used to make a much larger composite projectile for use in an atlatl dart thrower, just imagine what that thing is going to do!


-Research Spotlight with Joshua Lynch - Composite antler/microblade atlatl points

-Archaeology Test Kitchen's Witches Brew

  Thanks for stopping by!


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