Hey, I thought I would post these up here. I knap mainly glass and some flint ships ballast I find and though it took me about an hour and half to make a point from a bottle base when I was learning it only takes me about 30-45min. now unless it's a really big and difficult piece. I made these 4 up this afternoon, it took me about 2 1/2 hours. They are made from 3 different kinds of clear glass bottle bases I collect off the beach and at least 2 of them will be becoming arrowhead necklaces in the near future and perhaps the big one a small knife. To make the base into a preform, (remove the cup on the bottom of the bottle base and the hump on the top,) I used a small copper cap fitted on the end of a soft maple branch about 5in. long for percussion work, if you weight it or use anything heavier like a hammerstone you will get step fractures and end up snapping the point in two to boot! Then I used my preference of pressure flaker to shape them and do the final thinning, my preference being a soft steel boat nail, (similar to a horseshoe nail,) set in a short hardwood handle. To notch them I used a finishing nail pressure flaker.
The clear glass is the trickiest I find as it has a greater tendency to be brittle and step fracture so you have to be really gentle with it. Green is my favorite, or blue if I can find it, those colors knap better and brown is pretty good too but not as good. I do find some clear bottle bases though that knap a lot better and are not near as brittle, the largest point is one of those. It's hard to explain but it has a very smooth almost oily feel to it, the good clear glass does.
I hope the pictures are o.k. I took them in a rush.
