So I have had a good amount of free time on my hands between missions over here and thankfully have had some rock to work. It's been a great pastime and I sure have learned a lot in the hours spent chipping away.
One thing that has been helping me achieve thinner bifaces even from smaller spalls is to use pressure to set up platforms. I noticed that in the past I had been switching from percussion to pressure too late in the stage which resulted in more broken preforms that weren't as thin.
Because of the size of even my smallest 1/2" bopper I couldn't make those small perfectly created platforms needed to send small flakes across the face. Instead I would get imperfect platforms that would cause hinges or would crumble. I'm sure I'm not the only one doing this but would suggest switching to pressure a lot sooner than you feel necessary. With a little extra time and care I have been able to make very thin 2"-3" bifaces that I probably otherwise would have bean beaten into the chip pile.
Another thing that has been helping me when pressure flaking is changing my angle and force. In the past I would try to push in, and down against the preform, but never could get my flakes to run as far as I wanted. I noticed that even if my flaking tool was started parallel to the preform by the time the flake broke the angle of the tool in relation to the preform was about 30 degrees.
Much like in the percussion stage with pressure it is just as important to have your platforms set up in that sweet spot just above center line and well abraided. If you want to push long flakes the platform must be strong enough to support it. What has been helping me considerably is the angle I start pushing my tool against the edge.
Lately I have been starting to push my flaking tool at an upward angle from the bottom of the preform. I then start pushing hard inward, and in doing this my flakes have been breaking at about the time my tool comes parallel to the preform, this not only let's the tool get a good bite on the platform but pushes the flakes a lot longer because maximum force is reached when you are parallel to the piece instead of 30 degrees or so later.
This has been helpful keeping the point thin even when reducing the size of the preform to your finished point size. It's kinda hard to describe this without being able to demonstrate but hope it helps. I know for me it's allowed me to utilize small baseball sized spalls that otherwise would have been overlooked.
Y'all be easy
Seminolewind...out.