How to you know when it is Sharp?

I have three basic tests for sharpness. First I use the good old Murray Carter 3 finger type test. The finger test gives instant feedback on sharpness and lets me know that the edge has been apexed. I think the finger test is the best way to test an edge but having little nicks and slices in my fingers is kind of annoying so I try to keep that at a minimum.

After the finger test I cut some paper(thinner is better)and 550 cord. Before my sharpening is done the knife needs to push cut the paper and also slice 550 cord the way I like. The paper will show any trouble areas in the edge and the 550 cord lets me see how much "bite" the edge has. Sometimes if I over strop or round off the apex, the blade will push cut like a dream but not be able to slice the 550 cord worth a damn. I like my edge to instantly bite into the paracord. I loop the cord over the edge and see how much slicing vs. pushing is needed to cut the cord. If it takes too much pushing force to cut the cord I know my edge doesn't have that aggressive "bite" that I have come to love.
 
I use thin magazine paper and leg hairs. With the paper, I hold on one end and push cut the far end. I cut along the longer edge, with the grain. With experience, you will be able to tell how shape it is by the noise it makes on the paper (quieter is better) and by how easy the hairs pop off.

To help see the edge, I bought a cheap 30x loupe. It's probably not really 30x considering it cost just a few bucks, but it's plenty of magnification to see the edge. I have perfect vision, but the loupe shows so much more.

Also, I always thought sticky edges are that way because they're toothy. (I might be wrong.)
 
I like my edges to pushcut phonebook paper against the grain. I've found there can be a big difference in sharpness from a blade that just slices PB paper with the grain than a blade that slices against the grain, but both are what I would consider sharp though. And I like to leave a nice toothy edge, polished yet toothy if that makes sense:D
 
I use the edge for the tasks I or the owner of the knife intends. That is the ultimate test...anything else is really meaningless.

That said, for a basic "sharpening", a skilled honer can simply look at the edge and pretty much know if it is ready.
 
unit said:
I use the edge for the tasks I or the owner of the knife intends. That is the ultimate test...anything else is really meaningless.

That said, for a basic "sharpening", a skilled honer can simply look at the edge and pretty much know if it is ready.
Click to expand...

I'm really not trying to sound like a know-it-all or the world's-best-sharpener here or anything, but honestly I think the most skilled sharpeners will know when its sharp enough in that regard while its still on the stone, without even having to look at the edge at all. For 99% percent of "if it cuts what it needs to cut" type tests, I've never taken a knife off of the stone and went to cut and had it not sharp enough.

Truth is I think most people here are trying to get it as sharp as they can. There's adequately sharp, and then there's excellently sharp.

My preferred tests...

3 Finger Test - To signal when to stop sharpening and start honing
Shave hair - The lowest level of refinement I'll stop honing at
Whittle hair - If I'm trying to get it "as sharp as I can" when honing
 
Thanks for all of the responses.
Learning and having fun.
Right now I'm still using old telephone books and recycled copy paper from the office.
 
wdtorque said:
Thanks for all of the responses.
Learning and having fun.
Right now I'm still using old telephone books and recycled copy paper from the office.
Click to expand...

Key and most important aspects of working/sharpening on your knives.

Blessings,

Omar
 
Paper towels? Never thought of that. ????
I'm sure I can make a mess of one, probably look like a puppy ate it when I'm done. :eek:
 
When the blade cuts through weed whip string with one pass it's good to go for just about anything.
 
Usually when it cuts a piece of newspaper or time magazine paper into little slivers without catching the length of the blade.

The cut in the paper also tells a lot. If it is really sharp, it won't deform the paper as much as a duller blade will. It also has a different sound.

I'd rather have an edge that will do this and last a while than a sharper edge that is more easily damaged.
 
Paper towel will show up ANY burr or rough spot, as will kleenex. Kleenex
is a bitch, but if your edge will cut it cleanly, it's sharp!!! But be aware your
edge will probably be far more easily damaged than an edge with a little more
"meat" on it.
 
Answer #2 - When you can throw a paper airplane at the knife and either sever pieces of the plane off, or stick it on the edge... LOL! A fun test of sorts to try just for kicks.

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Thrown from just beyond arm's length away to ensure easy hits but it still is a challenge to "catch" a throw on the blade!
 
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Yep, that'll do it.
Color me impressed!!

Kleenex, paper towels, flying planes.
And there is a guy on BritishBlades who whittles cigarette paper?
What the Hay?
I'm glad I don't have low self esteem because if I did I'd just quit and throw all my stones in the dumpster!
 
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