Ultimate sharp test

paper/ newsprint . You can really feel the edge when you cut it, brining forth any imperfections/chips/if any
 
Whenever I hear "ultimate", I always rush and get out my tinfoil cap.

My "good enough" solution is phone book paper, with and against the grain. I'm that kinda guy. (And I only require good enough.)
 
When you just look at it with a mean scowl and it still cuts you . Lol
 
I also test with fine paper like phonebook pages, receipt paper, etc. If it easily slices through that, consistently from one cut to the next, that basically shows me the edge is fully apexed and no burrs are getting in the way. I've learned over time, if it consistently passes that test, the edge will also perform well for every other typical use I give it.

I don't generally pursue other 'ultimate' sharpness tests like hair-whittling, etc., as those edges are almost always fleeting if you use the blade for anything other than hair-whittling. Edges that fine won't generally be durable enough to last very long through much else.
 
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I figure that's the only reason people keep sending me phone books......they want me to have enough paper so I can test the sharpness of my knives.
 
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I haven’t seen anything more “ultimate” than “double hair whittling”:
ETA: Well - I guess unless you count using a BESS with pre-tensioned wires. That’s probably the most accurate test out there now.
 
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I've been interested in this for a while. I've decided that shaving hair is a low bar. Cigarette, receipt or phone book paper helps find nicks and problem areas, but I have edges that will perform very well on the paper, but will not cut anything else very well. There is that push-cut sharp, which we test on BESS machines, but I think testing the blade's push- or pull-stroke effectiveness is more useful for a kitchen, EDC, or camp knife.

My new favorite medium to test for a practical cutting edge is paper towels, or maybe kleenex in a pinch. If it will do paper towels agressively, it will zip through brown onion skin, big giant carrots and brocolli, meat, fish, even...

I hear things. I heard that there is a small and very exclusive group of guys who take this very seriously. Their chosen test media for their sharpest blades is:

Yes, you guessed it. Well some of you guessed it. Rotten tomatos. The more rotten the better. Overipe tomatos are child's play, these guys can slice them with their lawn mower blades. It's all about rotten tomatos for these guys.

Of course, these guys really know how to sharpen a blade!!!
 
Been constantly trying to improve my freehand sharpening and chasing the ultimate sharpness, mostly for fun just to test my freehand skills. When I test, I first check if my edge can cleanly slice paper towels when just holding it between two fingers. I see some pinch the paper towel between four fingers to make it taut and then slice in the middle, but I feel like that makes it much easier to do. I've had edges that can slice paper towel cleanly holding with four fingers, but not slice well when just holding it with two fingers since the other side of the paper towel will be limp. So I think the latter is a better test of pure edge aggression. If any edge I make can do this, I'm satisfied most of the time.

After the paper towel test, I'll check if the edge can whittle hair with and against the grain ("double hair whittling" mentioned above). Whittling with the grain being much harder to do. I don't specifically aim for my edges to be capable of doing all 3, I just go through whatever progression I happen to be doing at the time and then check. Certainly more successful with some steels compared to others and I usually only get edges capable of 2 out of the 3 tests. When I make an edge that can do all 3 I know it's a crazy edge.

Another test I do occasionally that I saw somewhere is to roll up and tape a piece of magazine paper to stand it upright, then try to slice a piece out of the roll from the side without knocking it over. Don't do this one often cuz I don't really have access to magazine paper most of the time unless I get a catalog in the mail, but it'll impress your friends who aren't sharpening nerds 🤣

I'd like to try a BESS tester someday, but instead I usually just end up spending the money on new knives or maybe stones.
 
Khromo said:
My new favorite medium to test for a practical cutting edge is paper towels, or maybe kleenex in a pinch. If it will do paper towels agressively, it will zip through brown onion skin, big giant carrots and brocolli, meat, fish, even...
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Thank you for this. I’ve recently read about paper towel slicing (with only 2 fingers) and have taken to trying it myself with much success.
 
Terry M. said:
Thank you for this. I’ve recently read about paper towel slicing (with only 2 fingers) and have taken to trying it myself with much success.
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Terry, I first started to figure this out when I was just getting into serious sharpening, and I put a mirror polish on a 1095 ESEE-4. I was working in the back yard and I had to cut some soft plastic or rubber irrigation hose, and that shiny knife took forever to cut through some fairly soft hose. The same blade would do pretty well with the paper tricks, but not much else.

I am finding 600-1,200 stones and a very few strokes with just one strop get me an agressive cutter that will still do basic paper tricks and shave hair reliably. I have some knives with reflective bevels that won't cut paper towels for beans! That type of edge might be well suited to thoracic surgery, but it is not well suited to EDC, for me, anyway.
 
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Khromo said:
Terry, I first started to figure this out when I was just getting into serious sharpening, and I put a mirror polish on a 1095 ESEE-4. I was working in the back yard and I had to cut some soft plastic or rubber irrigation hose, and that shiny knife took forever to cut through some fairly soft hose. The same blade would do pretty well with the paper tricks, but not much else.

I am finding anything beyond 60-1,200 stones and a very few strokes with just one strop get me an agressive cutter that will still do basic paper tricks and shave hair reliably. I have some knives with reflective bevels that won't cut paper towels for beans! That type of edge might be well suited to thoracic surgery, but it is not well suited to EDC, for me, anyway.
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That's also why I'm no longer too impressed with high-polished edges. Years ago, I'd tried to cut through some polybutylene tubing with one of my knives - a Case, in 420HC - with an edge I'd created and polished using a guided system. It was great with the sharpness 'tricks' in testing it on paper & such. But it was worthless for that tubing - it just slid across it without biting. Since then, all my edges get finished somewhere between DMT XC (220) and a medium Spyderco ceramic, all of which still retain some real aggression in slicing - that initial bite is important for a lot of cutting tasks.
 
Obsessed with Edges said:
That's also why I'm no longer too impressed with high-polished edges. Years ago, I'd tried to cut through some polybutylene tubing with one of my knives - a Case, in 420HC - with an edge I'd created and polished using a guided system. It was great with the sharpness 'tricks' in testing it on paper & such. But it was worthless for that tubing - it just slid across it without biting. Since then, all my edges get finished somewhere between DMT XC (220) and a medium Spyderco ceramic, all of which still retain some real aggression in slicing - that initial bite is important for a lot of cutting tasks.
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Woof!
 
If I can't feel a burr and it will pick a few arm hairs, then that's good enough for me. For what it's worth there is an old carney trick that is used to sell whatever variation of "ever-sharp" knives, you can get good enough to cut a transparent slice of tomato with a butter knife, if you have the feel for it down. So when it comes to "ultimate" cutting technique is a variable that has to be factored in
 
You need to toss a silk scarf up into the air, then bring your katana down through it.

If the passage of your katana through the silk scarf disturbs its fall due to gravity in any way, shape or form, then your edge isn't sharp enough, Grasshoppa.

iu
 
Ultimate sharpness? Reminds me of a story related to legendary samurai and swordsman Miyamoto Musashi. Story goes, Musashi and another Samurai were debating whose sword was sharper. To prove his sword was sharper, the other Samurai stuck it, tip down, into a stream. As leaves floated down the stream they were cut in half by the edge, proving a vicious and razor edge. Musashi took his own sword, named Cloud Cutter, and did the same, inserting the blade, tip down into the stream. As the leaves floated down stream, they floated around the sword. The challenger laughed and said that this proved the superior edge of his sword. Musashi responded, the leaves avoided the edge of his sword altogether, because it was THAT sharp.
 
navman said:
Ultimate sharpness? Reminds me of a story related to legendary samurai and swordsman Miyamoto Musashi. Story goes, Musashi and another Samurai were debating whose sword was sharper. To prove his sword was sharper, the other Samurai stuck it, tip down, into a stream. As leaves floated down the stream they were cut in half by the edge, proving a vicious and razor edge. Musashi took his own sword, named Cloud Cutter, and did the same, inserting the blade, tip down into the stream. As the leaves floated down stream, they floated around the sword. The challenger laughed and said that this proved the superior edge of his sword. Musashi responded, the leaves avoided the edge of his sword altogether, because it was THAT sharp.
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This is awesome! Never heard this one before. Thanks for sharing
 
I see Mr. ronbowusmc gave us a nice bone to chew.

gadgetgeek said:
If I can't feel a burr and it will pick a few arm hairs, then that's good enough for me.
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The burr could be aligned with the apex so you won't feel it with your fingers. It will shave and slice tomato but as soon as you hit a harder material (like pine cutting board) the burr will fold and there goes the sharpness.
In this case the BESS tester would show there is a burr. The burr will fold over when hitting the wire.

But; what test can you do if you don't have a BESS tester? Apparently ''I can't feel the burr with my fingers'' test is not very reliable. How about paper test? This aligned burr can also cut paper if it can shave and cut tomato.
 
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