into mass vs out of mass

[aaron]

I was intrigued by the recent post mentioning into mass / out of mass. I'm not sure I understand. Is there a youtube video showing it?
Let's say you are taking a run of flakes down one edge of an arrowhead, starting at the tip and working towards the base. Let's also say that you are angling the flakes and not just flaking perpendicular to the edge.

Is the difference between IM and OM based on weather you angle the flaker towards the tip v.s. toward the base?

[Outbackbob48]

WE had some very heavy discussions on this with James Parker at the classic a few yrs back, Here is what I remember. If you start at the tip and push a flake off the tip end and then step back and push a flake towards the one you just removed. This would be out of mass, If you start at the base and push a flake towards tip and continue to push flakes towards tip you would be going into mass. Clear as mud right. Bob

[Chippintuff]

I guess I have missed something. This is discussed in a some of the books on knapping, but I have never been able to see that either direction was more or less difficult than the other. If anyone has established that there is a difference in difficulty, I would like to hear it.

Flaking into mass by chipping into a surface dip and trying to push the flake out the other side (high) cleanly is almost always a No-No, but that is not the same into the mass.

WA

[Outbackbob48]

Chippintuff, It also has been explained to me as removing a kernel of corn from a cob and then removing the next kernel by pushing toward the blank space of previous kernel, out of mass so to speak.Also if I remember correctly out of mass creates a flatter cross section and a into mass creates a median ridge type cross section assuming both edges were the done. That about covers everything that I know about into and out of mass. Bob

[Zuma]

All I know is I went into mass at 9am and was out of mass by 11.
Zuma

[Swamp Thang]

All I know is I went into mass at 9am and was out of mass by 11.
Zuma