Making Sharp Rocks Afield

David E

David E

Joined
Nov 10, 2005
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Some folks dismiss the value of a knife by smugly claiming, "I can always make a knife from a rock if I had to......"

Ok...................so how many of you have actually done it?

How well did they work ?

How long did they last ?

Were you able to cut open a can of stew with it ?

Any pics would be great !!

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Did it once (please keep in mind that I am very much a beginner).
Depends on what kind of rock. I tried using some form of granite, some mixture of chalk and something else, and what I believe to be flint. Flint was the best, but it had too many inclusions (said my "instructor) - whatever those are. Basically, you need either obsidian or good flint and a round, flattish hammerstone. Then you just chip away at an angle to get the edge. Of course, I really sucked at it. Haven't had the chance to try it again.
They don't last all that long except, very specifically, for cutting (mainly the flint, the others were TERRIBLE) - as you cut, the edge slowly deforms as flakes fall off, although to the same extent, it stays fairly sharp longer that way - just the edge becomes more crooked.
Can't open a can of stew - but you could fireharden a sharp wooden stick and use a rock to hammer it open... I suppose. Not something I would want to try though. Might as well just carry a small can opener/multi-tool/SAK - in which case... why bother with making a sharp rock?

IMO, you would have much better luck making a wooden spear, fire-hardening it, and working with that.
Also, certain pieces of bone make fairly decent spear-points and knives - though of course, you need an abrasive rock to work them.
 
You can do this by using a technique called flint knapping. It's the same technique used by natives to make spear and arrow heads. It's really pretty easy after a little practice, but can take a while to master.

Here is a gallery of flint knapped knives, arrowheads, etc...: http://www.msu.edu/~doneycar/flint.html
 
flint knapping does produce a wicked sharp edge. You can cut rope without much of a problem with a good piece of serrated rock:D I have done it before and it does produce a very sharp edge. Never tried it on metal and as far as longevity, I used it a few times and threw it away, sort of a disposable razor:D
 
Sounds like a specific kind of rock is needed..........along with a significant amount of time.

Neither of which seem to be a smart thing to rely on in a survival or emergency situation.

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Perhaps not, but it is a useful skill to have if you ever really find yourself lost in the wilderness with no supplies or tools.

It also helps when the rocks are closer to the surface than they are around here. ;) Of course, around here, it's pretty hard to get lost, since you can see about five miles in all directions.
 
I understand it would be a good skill to have, but someone in another thread tossed that out like it's nothing to knap one out using any rock in no time at all, minimizing or totally ignoring the better idea of taking a good knife with you.

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I've never done it, but if I had to I'd look for rocks that are in streams and rivers or riverbeds; and if possible something with a reasonably fine grain to it. Most water-rocks will be fairly smooth and thus easier to sharpen with. Also, I think I would start with stropping on the rock unless dealing with an incredibly dull knife.
 
David E said:
I understand it would be a good skill to have, but someone in another thread tossed that out like it's nothing to knap one out using any rock in no time at all, minimizing or totally ignoring the better idea of taking a good knife with you.

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It sounds like someone watched "The Hunted" too many times. I don't which was more lame, Benecio Del Toro forging a new knife on a wood fire with his bare hands, or Tommy Lee Jones knapping out his stone knife in three minutes.
 
yablanowitz said:
It sounds like someone watched "The Hunted" too many times. I don't which was more lame, Benecio Del Toro forging a new knife on a wood fire with his bare hands, or Tommy Lee Jones knapping out his stone knife in three minutes.
Click to expand...
Actually, with practice, I would be surprised if knapping a simple flint "axe/knife" would take more than 5-10 minutes - the main issue would be the risk involved in knapping off large pieces sufficiently fast enough while keeping the edge intact - much like building a fire-harp can take a long time.. or no time at all depending on skill. The one I made had a fairly functional, albeit somewhat crooked edge, and it only took me 6-7 minutes.

But is it really worthwhile? I think learning how to make a hand axe, a scraper (for skins) and perhaps an awl (all of which I plan to do at some point) would prove fairly useful. But how quickly would this skill be gained? Would it be like tying shoelaces.. or more like learning how to paint?
 
I'll admit I've never tried it, possibly because I've never seen a piece of flint or obsidian within a hundred miles of where I live. It kind of limits the usefulness of the skill when you have nothing to work with. Makes it hard to practice, too. ;)
 
Best place to look for ready-made rocks for field honing are in river/stream rapids, where the surfaces have been smoothed by tumbling and spinning against each other.

There is always rounding of these stones, which makes it difficult to sharpen right up to the choil/bolster area of the blade. A carrot-shaped stone alleviates this a bit, or breaking a stone against another will provide an abrupt stone edge for honing the base of the blade edge.

I wouldn't worry about exact stone composition - they're all hard enough for honing.

Hope this helps!
 
gud4u said:
Best place to look for ready-made rocks for field honing are in river/stream rapids, where the surfaces have been smoothed by tumbling and spinning against each other.

There is always rounding of these stones, which makes it difficult to sharpen right up to the choil/bolster area of the blade. A carrot-shaped stone alleviates this a bit, or breaking a stone against another will provide an abrupt stone edge for honing the base of the blade edge.

I wouldn't worry about exact stone composition - they're all hard enough for honing.

Hope this helps!
Click to expand...

Not to rain on your parade or anything, but we're talking about making stone knives, not using stones to sharpen steel knives. ;) Besides, around here you need a shovel to get a drink out of the river. The last time I checked the water was five feet below the surface. Not too many rocks tumbling around in there. :D
 
I have used stone blades of my own manufacture to clean animals. Many stone tools that we find in the archaeological record are simple flakes, produced from a core. These flakes are razor sharp when fresh but dull quickly. Especially if you nick bone. However with a properly prepared core, you can simply strike off a new one every so often. These are sometimes called expedient tools. A bit like an x-acto knife. Things like arrowheads, spear points, knife blades are sometimes called formal tools, as they are produced with a certain form and function in mind. Damaged or dulled tools can be reshaped and sharpened through a process called retouching. Often when a tool breaks, it is recycled into something else, a scraper or awl for example. Stone tools are extremely useful, but do not have the durability or tensile strength of steel. Stone blades do not do well with any sort of twisting, prying or lateral pressure, for example while prying apart a joint. :) The best types of rock to use have a high silica content and break with a conchoidal fracture pattern (think BB pellet and a pane of glass).
 
I've used basalts, gneiss, and even a few fine granite stones for EXTREMELY rudimentally sharp tools, basically made scrapers that would put a point on a stick, scrape out a simple bowl or most importantly, fuzz a stick or log to make tinder. Any non-sedimentary rock (and some limestones) when broken against another will likely create some sort of sharp-like edge. You're not going to gut and skin a deer or make a spear point out of one, but when you need an edge for scraping or a little help cutting it will work in a pinch. Obviously not like a knife that I would be carrying...

J-
 
I learned how to flint knapp years ago while on an archaeological excavation. Making a flake or a simple scraper isn't extremely difficult. However, knapping an honest-to-god blade takes an enormous amount of skill. Less like tying shoelaces, more like painting. It is most definitely an art. My hand axes look like something that a developmentally challenged Neanderthal child would produce.
 
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