California Knappers

Knapping Tips


Your platform should be less than 90°. Before striking, your working edge should be below the centerline.

After much repetition, your billet swing should be at a constant angle everytime you hit your stone. If you tilt your preform at different angles, you can control how long your flakes are and how much material you remove.

Where is your platform? Platforms made and struck below the center line of the mass make flakes.

To create a biface that is thin and lenticular in shape, thinning flakes are best struck from the side margins. If you try to thin from the ends, you will probably end up making a shorter biface and, also, run the increased risk of breakage from end shock. When thinning from the side margin, correct striking location and striking platform are very important.

Careful and properly built striking platforms are one major key to predictable flake removal. The platform should also be ground using an abrasive or granular material like sandstone. Grinding dulls the edge so the billet can grab hold of the platform rather than crushing a super-sharp edge that has no strength.

Step fractures are the result of the flake snapping off rather than feathering out completely. A number of things can cause this: 1) Holding the piece too tightly against a hard pad will sometimes interrupt the detachment of the flake. Hold your piece against the pad at an angle so that there a gap between the pad and the area where the flake will come off. When using a hard pad, a slot can be cut into the pad where the flake will fall. 2) If your pressure angle is too steep, this can cause the flake to dive in. 3) Pressure flaking into a large mass.

When you get into the pressure flaking stage on your biface, first straighten out your working edge. To take off flakes on one side of your biface, move your working edge below the center line. Begin removing consecutive flakes from the end of the biface where your thumb is located and move along the edge to the other end of your biface.

When you are ready to pressure flake your biface, the technique of upward flicking your working edge with a pressure flaker will create a 45 degree cavity platform. The pressure flaker is then placed in that cavity platform, pressure is applied inward and the flake is snapped off with a downward pressure. This technique allows long flakes and does not require constant abrading (or no abrading at all). Wear safety goggles or glasses to protect your eyes from small flakes propelling upwards.

When using traditional knapping tools, acquire hammerstones of various weights. Sandstone cobbles can be found along creek beds. Moose and deer billets can be purchased at pet stores. The antler pieces are sold as dog chews. They come in various odd shapes and sizes. You will have to be selective to find the right antler for your billet needs. The prices are reasonable compared to the rates from knapping websites. Flea markets are another good source to acquire deer antlers for pressure flaking tines. It will take a bit of searching to find your traditional tools, but it is possible to spend an inexpensive amount of cash to equip yourself with some Stone Age knapping tools.

After much practice, you have probably standardized your billet swing so that it is coming down at pretty much the same angle all the time. You are hitting your platforms pretty much the same way every time. Since this swing has become a constant, we have an opportunity to have some control over the thinning process and the length of the flakes we take off.
If you tilt your preform at different angles, you can control how long your flakes are and how much material you remove. Depending on how much material you are trying to get through, you may have to adjust the power of your strike as well or use a heavier billet. A lot can be accomplished by understanding how to use different angles.

You take your swing and you hope that you kept everything in position during that time. You try to keep from flinching or tilting the stone at the wrong angle. If you’ve been having trouble with the accuracy of your strikes or holding the correct angles, why not rest the preform on your leg where you can easily hold it at the proper angle. You’ll have better control and accuracy this way, as opposed to freehand knapping or holding your preform out in the air with one hand.
Everyone has their own style, but if you are having trouble with accuracy and angles, give knapping on the leg a try. The more you can control the variables, the better your knapping skills will be.

To shape your preform, lay your piece flat on your lap and knock off very small flakes from the edges of your preform. This will accomplish two things. First, you are starting to shape the desired form for your point. Second, you are moving the working edge to one side of the center of the mass on your preform. Flipping the preform over, your working edge is now below the centerline.

"One rule is useful to keep in mind when doing percussion flaking: follow ridges. Remember, the force spreads equally in all directions. This is true only to the extent that there is sufficient mass to transfer the blow. In practice, the force will spread furthest along the ridges. In other words, you should align your hammerstone blows such that the force applied will follow an existing ridge. This can be either a natural ridge on the core rock, or it can be the ridge left behind by a previous flake scar. By consistently following ridges, you will be able to strike the longest possible flake."
Excerpt from "Flintknapping, The Art of Making Stone Tools" by Paul Hellweg

"Striking Angles: The principal of conchoidal fracture must be kept in mind when determining the best striking angle. Remember, flakes are removed in a direction different from the angle of applied force . . . . The closer your striking angle is to the ideal angle of cone fracture, the longer your resulting flakes will be. If the striking angle is decreased (that is, the blow comes closer to being straight in to the core), you run the risk of obtaining step fractures. If the striking angle is increased, then only short flakes will be detached."
Excerpt from "Flintknapping, The Art of Making Stone Tools" by Paul Hellweg

"The common and effective technique for making bifaces is soft-hammer percussion using a bone, antler, or wooden hammer, also called a billet or baton or percussor. Bifaces, including some of considerable refinement, can also be made by hard-hammer percussion. . . . . Soft, as in 'soft hammer,' just means softer than hard -- that is , antler or wood as opposed to stone -- and relatively elastic as opposed to relatively inelastic. . . . . A soft hammer is particularly useful in thinning, flattening, and shaping bifaces because it is the easiest way of removing large, relatively flat and thin flakes with small bulbs of percussion. This is because when a soft hammer strikes a core, it compressese slightly, and the force is spread out and transmitted more slowly and evenly. The kind of flakes produced by a soft hammer are necessarty if one is trying to produce a large, thin tool with extensive working and with a straight edge."
Excerpt from "Flintknapping, Making & Understanding Stone Tools" by John C. Whittaker

"In order to select the best material for your [knapping] needs, you should have an understanding of the glass-like characteristics to seek in your raw material. Briefly, good knapping stone is:
1) Cryptocrystalline: The mineral's crystal structure is so small that it practically cannot be seen. In essence, the mineral behaves as if it had no crystal structure and thus transfers force in the same manner as glass.
2) Elastic: The mineral has the ability to return to its original state after having been depressed by the application of force. According to Crabtree, the best lithic materials are almost perfectly elastic.
3) Homogeneous: The material is of the same structure throughout; in other words, it is free of any impurities or inclusions which could hamper the flaking process.
4) Isotropic: The material has the same properties in all directions; that is, it behaves just like a heavy liquid. "
Excerpt from "Flintknapping, The Art of Making Stone Tools" by Paul Hellweg

"Alternate Flaking: Normal pressure flaking is next to impossible on blanks with thick square edges. These troublesome edges are best removed by alternate flaking; that is, by removing pressure flakes from alternate sides. Start at one corner and remove a short stubby flake by changing the angle of the antler tine to about 45 degrees. Then flip the blank over and remove a similar short stubby flake from the opposite side. For this second flake, do not positon the tine on the blank's original edge. Instead, start the second flake from the new edge created by removing the first flake. Continue in this manner until the entire thick edge is removed. Each time, flip the blank over and start from the newly exposed edge left by the previous effort. Once the entire edge is removed, then the rest of the blank may be worked by standard pressure flaking techniques."
Excerpt from "Flintknapping, The Art of Making Stone Tools" by Paul Hellweg

When starting with a raw cobble, take the time to READ your stone. Where are the high spots that need to be removed? Are there any 90 degree angles that require alternate flaking? Where is my centerline? What can I make from the stone? Taking the opporutnity to examine your cobble thoroughly is a good way to envision how you should proceed with the lithic reduction process.

A platform that has been "isolated" from the material around it is called an isolated platform. To create an isolated platform, you just simply remove a short flake on both sides of your ridge with a fairly thin pressure flaker. After this process, you have a platform that sticks out more than the rest of the edge. The energy is transfered much farther "down range" using isolations. This also alleviates breakage when the point gets thin.

Indirect percussion is a technique that is seldom used in modern times, but widely practiced prehistorically. It involves the use of a bone or antler punch and a hammer. The physics of punch use allows more massive flakes to be removed than by using the antler billet or hammerstone as a percussion instrument. The accuracy allowed by the punch is also evident. Since indirect percussion can be so precisely placed, the punch and hammer make it possible to apply a large force to very small platforms of a stone tool than in other methods of flake removal.

"Platform Preparation: In order to do the best percussion flaking, the edge of the lithic core should have a well-defined platform. If the natural platform is weak (slightly lipped, etc.), it an be strengthened by light abrading. Your hammerstone can do this task and thus serve a dual purpose. Abrade in one direction only, OPPOSITE to the direction flakes are to be struck.
If your core does not have a natural platform, then you will have to prepare your own. Do this by carefully using high angle trimming blows to remove small pieces of material on both sides of the desired platform. If done properly, this will leave a well-defined and isolated platform."
Excerpt from "Flintknapping, The Art of Making Stone Tools" by Paul Hellweg

Wyatt R. Knapp's "Flintknappers Tool Kit":
1. A leather pad of thick leather to protect your hand when pressure flaking.
2. A deer antler tine pressure flaker (or a copper tipped one). Antler tines work very nicely. They wear faster than copper but you get great pressure flakes. If you learn percussion work well, you will only need the pressure flakers for final edge sharpening and retouch anyway.
3. A medium sized antler baton, about 8 inches or so long and about 2 inches across at the business end. Make sure it is a good dense one. Antler is NOT harder to use than copper boppers. Knapping is not easier with copper. It is just as easy to learn to knap with traditional tools than it is with copper billets and such.
4. A few hammerstones of various sizes. Quartzite or some other hard stone of a nice egg shape. One about 1 1/2 inches long, one about 2 1/2 inches. Also, you can add a couple of sandstone ones that will be able to be used on easier material like obsidian or glass. You can usually find hammerstones by gravel pits, the lake shore, etc.
5. An abrader. Either of hard sandstone or a manufactured one.
6. A large thick leather pad to protect your leg while knapping.
7. A notcher. Make it from a cow rib bone, or an antler tine, or make a copper tipped one.
Now you will notice that of all those things, there is only one that would probably constitute a major purchase. That would be the moose antler baton. Prices for good antler batons can vary and there are deals out there. Just make sure the one you choose is good and hard, and dense.

". . . . learn the cause and prevention of these [biface] fractures.
1. End Shock: a fracture which runs straight and which has a slightly lipped edge. It is caused by the application of excessive force to an end of the biface. To prevent, either do not strike from the end, or -- if you must strike an end -- support the opposite end on a hard wood anvil.
2. Perverse Fracture: a spiral or twisting fracture which typically does not run straight. It is caused by striking a side margin with too much force or by attempting to remove too large a flake (again, from a side margin). To prevent, use less force and/or a better platform."
Excerpt from "Flintknapping, The Art of Making Stone Tools" by Paul Hellweg

"Serrated points are a product of the Early Archaic phases in the midwest and also occur in later periods in the form of small arrow points. . . . . On these points the serrations are made by accentuating the flake scar junctures. This is accomplished by leaving the edge ragged after pressure flaking and by carefully hollowing out the spaces between the junctures where larger serrations are desired. . . . the edges in between the junctures in some areas may be a little too sharp for clean flake removals, and it may be necessary to grind them a bit. To get into the hollows without touching the serrations a thin piece of sandstone or a quartzite flake can be used."
Excerpt from "The Art of Flint Knapping" by D.C. Waldorf

Keep your copper pressure flakers sharp by pounding the tip to a point. Then dress it with a file. This will keep the copper hard and reduce slippage on the edge of your stone piece.

"Safety Precautions: There are many tools involved in the shaping of stone, including safety tools. Safety glasses, gloves and footwear should be worn at all times. In the process of fracturing stone, sharp flakes can fly in many directions, endangering your eyes, feet and hands. For this reason, you should also have a designated place to practice your flint knapping, where sharp waste material can be easily cleaned up and is out of the way of regular foot traffic. A tarp laid down is a way to ensure easy cleanup. You want this workspace to be well-ventilated, preferably outside. Every time a stone fractures, microscopic razor-sharp particles are put into the air and can cause severe respiratory problems. A first-aid kit also is important. It's also necessary to have two different sizes of thick leather pads. One pad should be the size of your palm and is used to hold your material during the pressure-flaking process. The other pad must be large enough to cover the top and outside of your thigh while you are percussion flaking."
by Paul Cipriani

"Why do we heat treat? Heat treating alters knapable material that is otherwise unchippable and transforms it to a glass like characteristic. Heat treating will also improve the colors of some flints. Browns can become reds, grays can become blues, yellows become orange and so on. It's an oxidation of the minerals in the stone. Soak heating (heating for 36-48 hours at a constant temperature) is not necessary, but will further enhance this knapability and color change. Not all materials can be heat treated."
Excerpt from "Heat Treating Tips and Temperatures" by Mark Bracken

"The reason antler works so well [for percussion flaking] is that, as it hits the edge of the flint, it is soft enough that it sticks for a fraction of a second. This concentrates the force of the blow and releases its energy slowly, thus producing a wide, flat flake."
Excerpt by "The Art of Flint Knapping" by D. C. Waldorf

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.

Learn how to create deep notches by watching Mike Cook's YouTube video entitled, "Notching Arrowheads". Access the link

"The Below the Center Line Concept" by W. R. Knapp. Access the link

Check out the flintknapping videos by Marty Rueter. Access the link

Question and answer "Knapping Tips" on Access the link

"Anatomy of a Platform" on Access the link

It's important to "dress up" your knapping tools whenever the tip of your pressure flaker gets too blunt or your bopper head becomes deformed. Having the right tools and properly prepared is important to good knapping. Take the time to hammer and facet your copper pressure flaker to a tapered tip. Use a file to creat the final point on your copper pressure flaker according to your needs. Even copper boppers need to be hammered back into a dome shape or replaced with a new, rounded copper cap.

Check out "Flintknapping: Perscussion" at Michael Lynn has compiled and edited various helpful articles and tutorials on percussion knapping.

The major advantage of using soft metals, like copper, rather than antler, bone or wood is that the metal pressure flakers wear down less and are less likely to break under pressure.

"Vitreous minerals have a property known as conchoidal fracture, and an understanding of this principle is fundamental to an understanding of the mechanical principles involved in flintknapping. A force applied to vitreous minerals radiates equally in all directions; the radiating fracture lines consequently take on a cone-like appearance.
An excellent example of conchoidal fracture is the cone formed in plate glass which has been shot with a slingshot or BB gun. When the pellet strikes the glass, the force spreads not only inwards, but also outwards in ever widening circles. If the velocity of the pellet is insufficient, only a partial cone is formed. But if the pellet carries sufficient force, an intact cone will be removed from the glass."
Excerpt from "Flintknapping, The Art of Making Stone Tools" by Paul Hellweg

All good percussion work makes the same demands on the knapper: well-orchestrated motor skills, an understanding of fracture mechanics and a reductiun strategy.

The difference between a copper tipped pressure flaker and an antler tipped pressure flaker:
". . . . copper and antler pressure flakers are used differently. The copper has to be kept sharp because the force is being concentrated in a small area on a relatively heavy platform that is prepared by shearing and quite a bit of grinding. If the tool gets dull, it takes more force to detach a flake, so consistency suffers and energy is wasted. This means the tip has to be maintained perfectly and after every half dozen flakes or so . . . . On the other hand, the antler, not being as strong, will only splinter if one tries to sharpen it and use it like copper against platforms prepared for that tool. Edges prepared for antler are lightly ground, just enough to keep them from crushing while allowing them to cut into the softer antler tip. In this way, the tool 'hooks' on and when the inward and downward stroke is performed, the fracture is actually initiated slightly behind the edge. In this manner flake detachment is a little bit easier when a blunter tool like the antler is used. So, I maintain my antler tips a bit rounder than the copper."
Excerpt from "The Art of Flintknapping" by D.C. Waldorf

Working spalls with prehistoric tools and indirect percussion. Access the YouTube videos by Jim Winn: Part I, Part II, Part III, Part IV

"When a billet becomes worn and pitted, it will cause chattering and hinging, making clean flake removals difficult. Anlters can be reground with a power grinder . . . . A properly ground billet should be nicely rounded with no flat areas."
Excerpt from "The Art of Flint Knapping" by D.C. Waldorf

Flake Terminationrs:
"The termination refers to the distal end and edges of a flake, and there are four main types. . . . . Feather teminations are most common and ususally most desireable. Here the force and resulting crack that separates the flake from the core exit smoothly from the material, peeling off a flake with a sharp 'feathered' edge. In a hinge termination, the fracture surface turns sharply upward, forming a rounded 'hinge' on the end of the flake. A step fracture terminates the flake in a right-angled break. This usually means the flake was broken, and the original force and crack may have continued into the core, with or without completing the removal of the rest of the flake. In an overshoot . . . . the force and crack continues to the end of the core and then, instead of exiting on the core surface, bends downward and removes part of the end of the core."
Excerpt from "Flintknapping, Makinge & Understanding Stone Tools" by John C. Whittaker

Clovis Points:
"There are several types of fluted points and several different ways to flute them. Fluting is the process in which a large flake is driven off both faces from isolated platforns centered on the base. On Clovis points, these channels usually extend 1/3 to 1/2 the length of the point and they accomplish both basal thinning and provide a groove into which the shaft settles. Since notches had yet to be developed, the lashing was simply wrapped around the base, glue was applied and the whole thing became quite solid.
The first fluting platform is prepared by carefully chipping a rounded stem or nipple on the base, after which it is ground moderately to heavily. . . . For best results in fluting, the edge at the tip of the nipple should lie below the center plane, but not quite even with the highest point on the median hump. . . . If it is too higfh or too low, depending on the angle and weight of the blow, the flute will be too narrow or too short, or hinge deeply before traveling the desired distance. A too sharp or pointed nipple will b crushed, or if it is cracked or flawed, it will also fail. The material that the blank is made of will determine the strength of the nipple; it should be heavier for weaker or grainier stone. What are called guide flakes can be chipped off the base at each side of the nipple, further isolating it. This is usually done to a greater degree for the second flute. At this stage, the blank may resemble a basal notched point with shallow, wide notches.
The blow that detatches the flute is carefully, but firmly dealt to the nipple. If it is too straight in, the platform will be crushed or a rollout fracture will shear the piece in two. If the angle is too steep, the flake will feather out and not travel far enough. the ideal flute will be broad, run 1/3 to 1/2 the distance to the tip, and will terminate in a slight hinge. . . . The size of the billet and how the platform is held or supported also makes a difference. "
Excerpt from "The Art of Flint Knapping" by D.C. Waldorf

YouTube videos: Soft Hammer Percussion
Caddo Blade (Part I)
Caddo Blade (Part II)
Caddo Blade (Part III)
Caddo Blade (Parr IV)
Caddo Blade (Part V)

YouTube videos: Isolated Platforms by Jim Winn
Isolated Platforms (Part I)
Isolated Platforms (Part II)
Isolated Platforms (Part III)

YouTube videos: Non-Abraded Platforms by Jimmy Williams
Part I
Part II
Part III
Part IV
Part V

YouTube video: Knapping a Blade Core Using a Rocker Punch by Craig Ratzat


For more information about the California Knappers flintknapping get-together, contact:
Dino Labiste


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