Saw this in a movie

Question:
Is it possible to sharpen a sword so sharp that slik hankerchief will be cut in two under only its own weight if dropped on the face up edge?

Choices:
Yes
No
Lets find out

 

That's a standard test for sharpness. IIRC, there are several katanas that can do that. But it's been a while.

I heard of this too, supposedly muslum leader, Sal al Din during the crusades was supposed to have the sharpest sword in the world. He would show off how sharp it was by throwing a silk scarf in the air and catching it with his sword, the weight of the silk was enough to cut itself in half!... crusader myth

No. Only in the movies.

if the sword is diamond edged maybe.

1. It can't be done.

2. Only a fool would try to put that kind of an edge on a sword.

Makes for great folktales. The silk scarf, the leaf floating in the stream, etc.

All nonsense.

Go out and buy yourself a package of nice, new single-edge razor blades. That's about as sharp as it's possible to get steel. (Due to the molecular structure) Give these things a try with the razor blade.
Report back....

Glass can be made sharper than steel, it fractures down to the single molecule. There has been a surgeon for many years making surgical scalpel blades from obsidian, as they are superior to steel ones.

None of these things will work with glass either...

Heard about this frequently, never seen it. Best test would be a _very_ acute blade angle set onto a scimitar or equivalently curved sword blade. The curve of the blade is rather important, read Oakshott for the difference between shearing and slicing blades. The Saladin myth I've read has him slicing the silk, but leaves open the idea of silk falling against a still blade vs. freefloating silk hit with a drawcut.
Gotta agree with the guy earlier who asked why anyone would set that kind of edge on a sword - the more acute the edge the more susceptible to chipping, nicking and folding.

Absolutely, positively, never going to do it. Not with a katana, kybher knife, kukri, or shamshir, shashqua, sayf or sabre.
This myth owes more to a bad movie than any historical feat. Even in the story of Saladin, the Kurdish warlord sliced a silk cushion- note the active verb, sliced- in half, he did not simply drop a hanky on the edge of the blade.

May I mention that the only thing that could make the sword or whatever cut the silk is if one of the two, preferably the sword, had enough momentum to slam the two together. I have tested this before. If you have a pile of silk and you drop it from high enough, it MIGHT be able to gain enough momentum to cut itself in half, but it isn't likely.

I don't believe a stationary blade can slice a dropped piece of silk but, hey; I've been wrong before and would like to see it tested. On the other hand I believe it MIGHT be possible to cut it with a moving blade. Here's why.

I sliced the corner off a dangling sheet of newspaper with a katana. I did this while holding the paper by one corner and - almost casually - swung the blade at the dangling corner. The corner fell away as pretty as you please and my mouth fell open.

Of course I HAD to try again but, I could never duplicate it. (Shucks and other comments.)

I am not anything like an expert; never even took the exam to get a belt. The blade was not a national treasure. In fact, it wasn't even perfectly straight. But it was HAND MADE and not purchased from a store. Sensei insisted on that. And I never, EVER tried to sharpen it myself.

I'd loved to see this tested with a moving blade against a silk cushion and a silk handkerchief. It would have to be a draw cut and it would have to hit the blade at the right place, I THINK.

As I said, I couldn't duplicate the act no matter how hard I tried but I promise you - my hand to God - I did it ONCE.

What skunk22 is talking about is a dropped piece of fabric in the manner of that Costner turkey "The Bodyguard"- which featured a stainless steel Franklin Mint "collector's sword", iirc.
Swinging a blade at a stationary, even momentarilly, piece of cloth brings in a whole new set of physics. I've seen it done with a piece of silk cloth "thrown" out so it's just temporarilly floating on the air and the cutter using a wootz knife (made by Pendray iirc) with about a 12" blade to cut through the material. Apparently wootz, possibly for something to do with the carbides, "grabs" and cuts soft materials better than plain carbon steels.

quote:

Originally posted by blacksmithal:
What skunk22 is talking about is a dropped piece of fabric...

Yes, that was the original topic and if my comment is inappropriately off target I apologize. My thinking is that the two tests might be combined into good TV.

quote:

..."collector's sword", iirc...Pendray iirc)... Apparently wootz, possibly for something to do with the carbides, "grabs" and cuts soft materials better than plain carbon steels.

What does iirc and wootz mean, please?

I'd argue it's possible, though not in the golden age of sword use. With modern technology and computers that can calculate and measure down to millionths of a micron, it could very well be possible to sharpen a sword edge to the sharpness you are speaking of. Though no sultan in the past has ever had a sword that sharp.

Though I can't be sure I haven't researched it enough. I'd argue that finding out just at what sharpness the silk, under its own weight, would cut it's self on a blade is prudent. For all we know silk(being made of the fine fibers that it is made out of, and depending on the grade) could do this very thing on a not so sharp blade.

Do you remember the "pyramid power" episode of Mythbusters? In that one, they put a shiny, new razor blade under the electron microscope, as well as a dull one.
Even the sharp one looked like a jagged old saw blade; it was just considerably LESS jagged than the used razor.
Again, it's the nature of steel at the molecular level; there is a limit to the degree of "sharpness" that can be obtained.

By using different materials, we might do better. Scientists recently made a tungsten "needle" with a point about the size of a single atom:

http://www.aip.org/pnu/2006/split/788-2.html

Perhaps with some of the modern composite ceramics a super-sharp edge could be obtained.

Science-fiction writers have played with the idea. One notion is the "fractal" edge, which would theoretically be almost endless. No materials exist which would allow such a construction, however.
Another idea is Larry Niven's "variable sword", in which a single-molecule thick "nanowire" is encased in a force-field.
William Gibson used the idea too in the short story Johnny Mnemonic; the Japanese corporate assassin uses a similar device.

quote:

What does iirc and wootz mean, please?

IIRC = If I Remember (or Recall) Correctly.

Wootz = A type of steel probably originating in what is know India and then spread via various conquests and empires like the Persian Empire to what is now Iran, Iraq, and Syria. The steel has a large amount of carbides gave the steel a look of water or intricate patterns (Damascene) and created an very sharp edge. The pattern gave rise to the term "Damascus" steel. The art of making Wootz steel was supposedly lost, but several people have come up with methods of making this steel. Modern "Damascus" steel is actually "pattern welded" steel, not the original Damascus.

FWIW, As I recall the legend of Sal al Din, he cut a silk scarf in mid-air with a moving blade. This is far closer to being feasible than cutting a scarf by dropping it on a stationary blade.

quote:

Originally posted by master_sergeant:
FWIW, As I recall the legend of Sal al Din, he cut a silk scarf in mid-air with a moving blade. This is far closer to being feasible than cutting a scarf by dropping it on a stationary blade.

That's my recollection as well, but my source is from a movie that was old when I saw it in elementary school. (The '50's.) I can't remember the title.

Not to say that the movie makers didn't have their own source as well.

And much obliged for the definitions, as well.

Yes. Some steel can be made this sharp. it depends on the density of the steel & extreme craftsmanship in sharpening. The weight of the falling cloth would be a critical factor but I have seen one 100 year old Japanese Tanto this sharp.
There are reports of archeologist finding stone tools knapped to a single molecule edge. Likely by accident.
We, as Americans, don't have a tradition of truly sharp edges. How many pocket knives can shave? I have a heavy field knife which can easily shave and it is very useful in the woods, even as a machete. Great cutting power.

quote:

Yes. Some steel can be made this sharp. it depends on the density of the steel & extreme craftsmanship in sharpening. The weight of the falling cloth would be a critical factor but I have seen one 100 year old Japanese Tanto this sharp.
There are reports of archeologist finding stone tools knapped to a single molecule edge. Likely by accident.
We, as Americans, don't have a tradition of truly sharp edges. How many pocket knives can shave? I have a heavy field knife which can easily shave and it is very useful in the woods, even as a machete. Great cutting power.

Your post is ridiculous. First off, no sword can cut a single piece of silk in half simply by dropping it on the blade. It doesn't matter how sharp it is. And the "density of the steel"? No matter how many times a blade's steel has been folded, it will not get past a certain density- which modern tool steels already have. (One of the big reasons for folding the steel that Japanese smiths traditionally used was that the as-smelted product they made was full of porosity, besides being uneven in quality.)
Secondly, Americans not having a tradition of truly sharp edges? Again, much of American soceity was rural until within the last few decades, and in a rural soceity one of the things which is learned is to sharpen your tools properly. Whether you were a butcher, a farmer, a carpenter or a rancher, not having your tools properly sharpened made your life extremely difficult, and in many cases could actually endanger it. I've examined carpenter's chisels that were well-preserved from the 19th century- you could shave hair from your arm today with them.
And until the last few decades of the 20th century, many Americans would stop in at their local barber for a shave. And this would be carried out with a hollow-ground straight razor- and trust me, these blades were sharpened and stropped as sharp as a blade can get, otherwise the customers would complain- loudly! And even a hollow-ground razor, with a polished edge, will not cut a piece of silk that is simply dropped on it.
Now, if you were to attach a 2 lb weight to each side of the silk cloth before dropping it, you might get a different story...

Total bunk.

You can not cut a silk (or any other cloth) scarf simply by letting if float down on it. Period, end of story.

A blade can only be so sharp and no blade will ever be so sharp that it will require next to no force to cut with. the sharpest that a blade can get is as sharp as your average Bic razor. Thats a big ole no.