Flakes?

[bushman]

I went and got a plate of obsidian a little over a ¼ inch thick. The outside edges where mostly 90 degrees, a few places on the edge where more then 90 degrees, and a few where less. Where the edge was more then 90 degrees I was flaking on the lip so that the angle would be less then 90 degrees. When I tried to presser flake I was only get flakes about a ¼ inch long at the most. Why couldn’t I drive off longer flakes? Also when I tried to do some percussion flaking my flakes would start out shallow then dive in to the obsidian before coming back out and off. So the flake scar looked like a bowl shape almost. A few times the flakes went so deep that it almost went right through the obsidian plate. Why is that? Was my platforms wrong? When you make a platform what exactly are you doin? Are you just roundin the edge over? I tried to watch some movies on youtube but I have really slow dial up internet where it takes me 5 hours just to download a movie that is only a minute long, and I aint got that much time to waste on here. Any help would be greatly appreciated. Thanks
Bushman

[sailordad]

well ya need to do whats called "turn the edge"
ya need a zig zag pattern on the edge and ya need to start with smalled flakes to create some convexity so flakes will travel further
flaked dont like to run long on flat surfaces or convex surfaces
other than that all ican say is if yant watch the vid on yo tube ya need to find some one in your area that works with slabs nd ask them to show ya how
me i started with slabs of obsidion for the most part,still use it alot
i learned on my own by watching the vids on you tube
good luck

[aaron]

yeah, like sailordad said, flakes don't want to run across flat surfaces- so you have to create a curve by doing some shorter flakes first. each flake should go slightly longer than the previous one. with a thin piece like 1/4 inch, you will not be able to build much curve. when you make a platform you are doing more than rounding the edge... you are creating the desired angle between the platform and the surface to be flaked. if the angle is 90 or close your flakes will be short and "bowl shaped". besides creating the right angle, you are also positioning the platform at a certain place with respect to the "center palne " of the piece. if you are too far below the center plane your flakes will also be short, hinged, or "bowl"ed. keep at it,.. it gets easier.

[aaron]

center PLANE , that is.
dulling the platform is done with an abrader, but creating the right angle is done by taking tiny flakes off in the oposite direction you will be flaking. this is called faceting. faceting also moves the platform closer to the face to be flaked. to move the platform away from the face to be flaked, you do the opposite of faceting which is called trimming. trimming is taking tiny short flakes in the same direction as you will be flaking. this also creates the curve you want.
generally, you want platforms close to the center plane, but with thin pieces you may want to go above the center plane so you have a nice curve to follow.

[stickbender]

     Bushman, another reason you are getting the bowl type gouges, is you are probably not grinding, or abrading the edge you are pushing against enough. I did that occasionally, and today, at Eddies, (Mullet), He showed me what I was doing wrong, when I gouged a couple of pieces.  If you keep trying to flake that area, you will just keep digging deeper.  The flake will run to it and stop, so you are just repeating the same dig.  You will have to come in at an angle to clean up the gouge.  Once you have your zig zag and platforms set up, abrade, or grind with an old broken, or worn out piece of grinding wheel, or hard rough stone.  But abrade at an angle to the platform.  Then push in hard, and use your knee to push your hand, and pop off the flake.  It is easier to show you than to explain, especially, since I just learned it today.  But I can see where I was doing the gouging, occasionally, and why now.  So I will be grinding a whole lot More now, and if I should make a gouge, I will set up a platform, and come into the gouge from an angle to take it out.  I hope you can understand what I am trying to say.  Maybe Eddie will chime in, and explain a whole lot better than me.  
                                                                                      Wayne

[Newbow]

Pictures make terms like 'turning the edge' and 'zig zag' much easier to understand.  This link will take you to a pretty good "how to" pictorial:
http://paleoplanet69529.yuku.com/forum/viewtopic/id/4009
Good luck.

[Parnell]

Did you check out the 'bi-face reduction pictures' that I think is in the archive section now, that SawFiler, I think did?
That may help...

[bushman]

Thanks for all of the advice. I will take a look at “bi-face reduction pictures”, thanks Parnell.
Bushman

[sailordad]

Did you check out the 'bi-face reduction pictures' that I think is in the archive section now, that SawFiler, I think did?
That may help...

it wont hurt to look at the bi-face redution pice

however shanon does not use "slabbed"material
all his is done from rock spalls or nodules or tabs

you really need to find someone who uses "slabbed material" or plates as you called it

knapping slabs and knapping spalls are two differant kinds of horses,so as to speak
what you do to one to get it down to a preform is differant thean what you would do to the other to get it down to preform
i know how to knapp slabs quite well(thats what i learned on),i also knapp rock spalls.
trust me on this,what you do to one typ is differant on the other type

so i still say if your working with slabs(and it sounds like you are) you need to find someone that knows how to knapp slabs and sit with them and in no time
you will have it figured out,atleast the basics of slab knapping.get to a "knapp in".watch as many you-tube vids as you can tolerate,then go back and rewatch them.

like i said,i learned on slabs.i wish i would of had someone teach me the basics and i wish i would have found you tube sooner also.i would not have wrecked so many nice slabs with no results.but that is the price you pay when you are self taught