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Flintknapping Terminology

Here are some helpful descriptive terms commonly used in knapping...

For definitions on Tools, click here

Abrading... The process of polishing the edge of a preform's platform to strengthen the it in preparation for flake removal by percussion or pressure flaking.

Biface... A spall or piece of flint that has been flaked on both sides.

Bulb... Often called "The bulb of percussion" it is the area very close to the edge or margin of the biface where the flake originates due to pressure or percussion work. It can sometimes be deep and cause significant concavities along the edge. The bulb should be kept at a minimum. See drawing

Center Line...This term is used to describe the imaginary centerline of a preform as viewed from the blade edge. See drawing

Cobble...Some flints occur in cobble form. These are irregular shaped but smooth, and are formed in various sizes averaging from one to 5 pounds and are generally covered with a cortex.

Concave... A"cupped" area on the face of a preform or nodule. This should be avoided until the material around it has been removed thus raising this "negative" area to match the contour of the rest of the Blade or core.

Convex... The opposite of concaved. It is a rounded raised area. A lens shape is a good example. This is the foundation for good successful flaking!

Core... The "mother stone" or nodule which spalls are removed from. Also a carefully prepared worked piece of flint that Sharp useable blades are removed from.

Cortex... The outer "skin" of a flint nodule or spall. Usually a chalky white or brown material ranging from 1" to 1/4" thick.

Flake... A thin, sometimes broad and sharp piece of stone chipped from a larger biface or preform.

Flake Scar... This is the "scar" left behind where a flake has been removed.

Flute Flake... A special flake removed from the base of a blade or preform that travels up the face towards the tip. The purpose of this flake was to create a concaved channel to aid in the special hafting technique of Paleo era points.

Heat Treating... Flint was often heat treated by North American peoples. Things are no different today! The flint is very slowly heated and cooled to temperatures ranging from 350-700 F, depending on the material quality and type. Not all flints benefit from heat treating. Heat treating gives the flint a glass like attribute making it easier to chip.

Hinge Fracture... This is an undesirable flake that falls short of it's mark by " rolling" out. See image.

Isolated Platform... This is a platform that has been "isolated" from the material around it. This is done by carefully chipping the stone away from either side of it. This leaves the platform sticking out a bit. The energy is transfered much farther "down range" using isolations.

Knapping... The skillful act of chipping flint or making gun flints.

Margin... The edge or circumference of the biface or preform.

Nodule... A large to very large smooth or irregular piece of flint.

Overshot Flake... The affect of a flake that travels from one margin to the other and "clipping" the opposite edge.

Platform... A platform has 3 main components, this is discussed in "platforms". A carefully prepared area on the edge of a preform to be struck to create the desired flake. Or A naturally occurring area on a rough spall or nodule that would produce a desired flake or spall. Platforms are the key to good knapping.

Platform Bevel... This is the part of the platform that is actually struck.

Platform Support... This is the underside of the "bevel". It gives support to the platform at the time of strike.

Platform deltas... These are the results of flake removal. See drawing

Preform... A bifaced blade in various stages of reduction.

Pressure Flaking... The act of removing flakes by pressure using an "Ishi Stick" or flaker.

Percussion Flaking... Removing flakes by directly striking the stone with a billet.

Raking and Shearing... Raking is the action of carefully dragging a course abrader or other device to remove "micro" flakes from the edge of a biface or preform to change it's shape or give support to an edge before actual abrading is done prior to percussion or pressure work.

Spalling... The act of breaking up a nodule or cobble into workable and desirable sized pieces.

Spalls... The finished untrimmed large flake removed from a larger "mother" stone.

Stack... Another BAD thing. A series flakes that fall short of a single specific objective. Resulting in multiple failed attempts to remove a specific problem area. Read"Platforms" for preventative measures.

Step Fracture... A single flake falling short of it's mark by creating a "step" on the surface of the Blade. The thinner you get the more this demon haunts you.


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