Natural sharpening stones you can find on a

Rennd

Rennd

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I think I'm going to the beach this weekend, and I've got a bit of a shark phobia thing going on, so I probably won't do much swimming. Do you guys think I would be able to find any natural sandstone or something similar that would work for a sharpening stone to take home? I really need to expand my range of stones, but I'm low on cash.
 
At the beach, I don't know. Maybe the sand itself, which is silica-based, might be used like a coarse stropping slurry on wood. I think a lot of folks in the third world sharpen blades that way. I'd think a lot of the larger rocks found at/near the beach might be limestone-based (from calcium), which is too soft to be useful.

Having said (ahem, purely speculated ;) ) the above, it never hurts to try stuff out. That's the best way to learn what'll work, and what won't. :)


David
 
In Arkansas they quarry Washita stones which are composed of a microcrystalline quartz deposited in an ancient sea bed. These are available in different sizes, grits, and grades. Among useful, natural sharpening stones; these are among the best.
 
Just don't take a huge knife with you and start rubbing it on everything to test. Unless theres no one around of course!
 
Rennd said:
Ahh. Oh well. Where would one go to find something useful?
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Assuming 'on the cheap', my first choice would be just sticking some mid-grit wet/dry sandpaper to a smooth & flat piece of wood. The sandpaper can be purchased at Walmart or Home Depot or Lowe's, or any other hardware store (Ace, etc.). The sandpaper runs about ~$1 per sheet or so. A little bit of craft glue, or rubber cement or other temporary adhesive can be used to stick the sandpaper to the wood. Use it like a strop, with edge-trailing strokes. Anything from 220-grit and up will work, to either create, restore or maintain your edge, depending only on how fine you want go with the finish. 220/320-grit will be fairly coarse & toothy, 400-800 will leave increasingly fine degrees of 'satin' finish, most closely approximating a lot of factory edges, and 1000+ grits will work to leave a near-mirror polish.

At Home Depot specifically, you could also pick up a Norton 'Economy' stone in silicon carbide for about $7 or so. Ace Hardware carries very similar (nearly identical) stones under their own brand, for about the same cost.

You could also pick up or order (online) a DMT 'credit card' diamond hone, in Coarse, Fine or Extra-Fine grit, for about $10-$12 apiece.

The above suggestions in silicon carbide and diamond will handle most any steel, which is why I suggest them specifically. Other 'inexpensive' stones, such as 'natural' Arkansas stones, might not be very effective with more modern and wear-resistant steels.


David
 
Yes, my Washita was slow to sharpen 425M steel. Not a high end steel. Just a good user steel. A Washita stone is around 4-500 grit. For an Arkansas stone they cut the most aggressive. DM
 
Too bad about the shark phobia. They apparently make good strops. :D
 

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G. Scott H. said:
Too bad about the shark phobia. They apparently make good strops. :D
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I'd often heard of the very abrasive texture of shark's skin, and sometimes wondered if anybody had tried it for honing or stropping. That's the first indication I've seen that it's at least been tried (assuming the 'Shark Hide' description implies it's source, and isn't just slick marketing for a leather strop). Pretty cool. :thumbup:


David
 
Shark skin has small placoid scales in it which look just like shark teeth but are much smaller. The hardness of the scales is the same as the hardness of the teeth. If you made sharpening stones out of powdered teeth, I don't think the wear resistance would be too impressive.
 
Obsessed with Edges said:
I'd often heard of the very abrasive texture of shark's skin, and sometimes wondered if anybody had tried it for honing or stropping. That's the first indication I've seen that it's at least been tried (assuming the 'Shark Hide' description implies it's source, and isn't just slick marketing for a leather strop). Pretty cool. :thumbup:


David
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I wondered about that too, since SHARK HIDE is in quotes in the ad. :confused:
 
tiguy7 said:
Shark skin has small placoid scales in it which look just like shark teeth but are much smaller. The hardness of the scales is the same as the hardness of the teeth. If you made sharpening stones out of powdered teeth, I don't think the wear resistance would be too impressive.
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That makes sense. I'd think at best, the abrasiveness may be coarser as compared to the silicates in leather, but perhaps not as hard. A quick look at defining 'placoid scales' seems to indicate they're made of dentin (as are teeth), which in turn is comprised of 70% Hydroxylapatite mineral (naturally occurring mineral form of calcium apatite), which is about a ~5 on the Moh's scale of hardness. Hardened knife steels are usually in the 5/6-8 range on the Moh's scale, with the silicates in leather somewhere in the middle of that range.


David
 
Rennd, I once vacationed at Zion National Park, camped right alongside that beautiful stream flowing out of the canyon and spent many hours relaxing there and watching our kids innertube down the stream. There were literally thousands of hand-sized sandstones there worn smooth by the action of the stream, and I used one to sharpen a knife I had just found on the trail. Worked great, even though it was rather coarse. Then, a couple years back, our son sent me a photo from a village in China where a local used a flat-topped boulder on the edge of a stream to sharpen his knives. It was impressively worn down, I assume from generations of use. Finally, in the British Museum in London there are ancient sharpening stones from Egypt and Mesopotamia and Syria and who knows were else. I doubt that anyone was quarrying sharpening stones back then, you just used what you found in the neighborhood or wherever you happened to be passing through. Maybe they weren't splitting hair, but I bet they did the job.

On hikes I always have my eyes open for flat stones that might sharpen a knife. There are lots of them out there, and they don't cost a cent.
 
I just tried an experiment with some stones I picked up hiking through Letchworth Gorge. I am not sure what type of stone they are but both required a bunch of work with some 120 grit silicon carbide grit and a tile rubbing stone. One was quite coarse and the other almost a medium finish. They were slow to grind a cheap Chicago utility knife though they did, raising a burr and removing same I could just barely shave some arm hair off the "finer" of the two. Was able to blow those results out of the water in about five minutes with one of my favorite coffee cups.
In my neck of the woods, I need a geologist to point me in the right direction if I want better than mediocre results for my effort. I recall reading that the early N American settlers were very happy to learn Novaculite had been discovered around Arkansas, had been importing their finer stones from Europe up to that point.
 
I've been a bit luckier going after slate type stones. The trick is finding something that contains something hard enough to actually abrade metal. With a bit of chipping you can usually generate a flat surface. Or for the less adventurous, get a slate tile from a store and try one out. Good luck!

Now even if it doesn't have much abrasiveness to the stone, a drop of 4 micron CBN on it and you get a reasonably good natural stone finish.

It's reasonably easy to find a coarse stone, but a coarse stone with abrasive already in it harder than the knife steel is much rarer.

---
Ken
 
tiguy7 said:
Shark skin has small placoid scales in it which look just like shark teeth but are much smaller. The hardness of the scales is the same as the hardness of the teeth. If you made sharpening stones out of powdered teeth, I don't think the wear resistance would be too impressive.
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Shark skin (and ray skin) have been used for generations in Japan as wasabi and daikon 'vegetable' graters. These skins are good for that, but unfortunately not so good for sharpening steel.


Stitchawl
 
I just found this item in a book I'm reading, and since it fits in with the topic of this thread I thought I'd share it as an incentive to keep your eyes open for stones and rock formations in the wild that might be used to sharpen knives:

"The formation ... is purely of primitive and sandstone formation: blocks of fine black hornblende and hornblendic rock, used by the people as whetstones and grinding-slabs, abound in the river-beds, which also supply the clay used for pottery.“

From: Sir Richard F. Burton, The Lake Regions of Central Equatorial Africa, with Notices of the Lunar Mountains and the Sources of the White Nile; Being the Results of an Expedition Undertaken under the Patronage of Her Majesty's Government and the Royal Geographical Society of London, in the Years 1857-1859. Journal of the Royal Geographical Society of London, 1859-01-01. iBooks.
 
I watched a video once where a guy took an old mouse pad, a piece of sandpaper and a tongue depressor and put a razor sharp convex edge on a knife while sitting on a rock in the woods. I think it came from Hedgehog leatherworks, maybe but, I can't find it again.
 
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