Pro tip: check the bottom of a flint core for previous flake scars

I spent 6 months trying to knap arrowheads from a big chunk of flint and kept getting hinge fractures no matter what I did. Then an old timer at the local field day pointed out my core had old water erosion lines on one side that were causing the flakes to break wrong. Has anyone else missed obvious clues like that on raw stone and felt totally dumb after?

2 comments

2 Comments

webb.ben29d ago

Buddy of mine spent two weeks trying to figure out why his obsidian kept shattering before he realized he was knapping it on a concrete driveway and the vibration was doing it. Felt like a total idiot when someone pointed it out.

sean78229d ago

That's rough but honestly I can see how that would happen. I read somewhere that obsidian is basically volcanic glass so it's already under a ton of internal stress from how it cools. The concrete slab probably sends tiny shockwaves through the piece with every tap and that's all it takes to set off a fracture along one of those stress lines. I heard flintknappers sometimes use a big rubber pad or even a stack of newspapers to absorb that vibration. Makes me wonder how many other materials we work with have hidden stresses we don't think about until they blow up in our faces.