Author Topic: Direct percussion on obsidian  (Read 408 times)

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Offline paulc

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Direct percussion on obsidian
« on: September 15, 2018, 06:03:19 am »
What are you using for initial reduction of spall?  My moose billet is often not enough but my hammer stone is too much...I really struggle to get even, thin flakes that go all or most of the way across. Instead I get chunks off...or the edge just crumbles.

Thanks, Paul

Offline Ryan Jacob

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Re: Direct percussion on obsidian
« Reply #1 on: September 15, 2018, 06:23:03 am »
Now, Iím no good at direct percussion, but it seems like the real issue is platform set-up.
You donít know desperation till youíve split a stave with screw drivers.

Offline aaron

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Re: Direct percussion on obsidian
« Reply #2 on: September 15, 2018, 02:01:52 pm »
Maybe you just need a bigger moose billet? I do most of my big bifaces with moose. Im talking bifaces over a foot long. If I want to spall a 30 lb nodule, i use solid copper, but the spalls are worked with moose.
Ilwaco, Washington, USA
"Good wood makes great bows, but bad wood makes great bowyers"

Offline paulc

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Re: Direct percussion on obsidian
« Reply #3 on: September 16, 2018, 04:32:29 am »
Definitely way out of my league...I'm talking working a spall the size of your hand and just trying to get it arrowhead thin before I've reduced it to rubble.

Paul

Offline aaron

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Re: Direct percussion on obsidian
« Reply #4 on: September 16, 2018, 05:49:39 am »
As ryan said, it's probably platform prep and or surface geometry. flakes don't go all the way across until:
1. the face is rounded all the way across
2. the edge is near the centerline
3. platform angles and sharpness are correct.
so , first step might be to use short flakes to make a centered edge all the way around. Next, develop nice convex faces (and maintain the centered edge). Then, prepare some nice rounded and dull looking platforms at places where a ridge meets the edge. .... Now you'd be ready to start taking longer flakes.
Ilwaco, Washington, USA
"Good wood makes great bows, but bad wood makes great bowyers"