How do you test sharpness?

SVanderkolff

SVanderkolff

Joined
Oct 31, 2002
Messages
979
I am curious as to how you test the sharpness of your knives. I have a set of Norton wet stones that I use before I send out my knives but I am not sure how to go about testing them to ensure the edge is right. Any help greatly appreciated.
Thanks
Steve
 
I think it depends on the use of the knife. I test kitchen knives differently than I do utility or hunting knives. I usually test kitchen knives on rolled over newsprint or magazine paper. I may also test them on a tomato or other food. Hunting knives I will first run through a piece of paper to make sure there are no bad spots in the blade, then I will try them on hunks of scrap leather. Try to think of what the knife will be used for, and then come up with a comparable test.
 
I tell you what Steve, then knife that I got off you was as sharp as any I have received, so just keep doing them the way you are!
 
Bruce Bump said:
I usually toss a hair into the air and slice it lengthwise before it hits the ground.
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Ya right.:D I test sharpness by finding a fly and while it's buzzing around slice the microscopic hairs off it's back without killing it. Seriously though if i can shave with a blade it's sharp enough for me. Especially if if the hair comes off like wiping dust off a table. Also test by skinning tomatoes,able to push through phone book paper ,run it across my fingers tips to see if it will fillet skin, ect. Looking at the edge under a micro scope to see if everything is just perfect would be good too. I gotta get a magnifying glass soon.:D I'm not that picky though if I shave well with it good enough for me usually.
 
From a collector's perspective, for a quick and easy check without attracting a lot of attention (say for example, you are examining a knife at a maker's show table).
Simply run the entire length of the cutting edge at a slight angle along your fingernail (thumb, from top of nail to bottom). A sharp blade should bite the nail as opposed to just
skipping off it. I often find the general cutting edge to past the test, however close to the tip does not.
 
initially, I'll drag the edge laterally over my thumb old skool. Then I check for a burr by touch. If there is a burr, the edge is not fully sharpened and any other test is meaningless until the burr is gone.
 
What I expect from a blade I purchase at the very minimum is the ability to
1. shave hair in both directions (so I know there's not a huge burr)
2. slice newsprint with the grain easily.
If it won't do that, I'm usually feel some disappointment.

When I sharpen I'm not happy unless it will easily slice newsprint cross grain and this is what I hope for when I receive a new knife. Very few have been capable of a true 90/90 push cut with no draw upon receiving them, and I struggle to get that myself, but that would be ideal.
 
Light.
then fingernail.
then paper.
then shaving.
I used to occasionally shave curls off a hair, but that seemed excessive and I cut off the pony tail anyway.
 
I have a bare patch on my otherwise hirsute leg. I work on the edge until it can shave easily. It's a good working edge, and I figure if the customer *needs* it sharper than that, he ought to know how to do so.
 
I can feel the edge with my fingers and tell if it's sharp or not.

Stopped shaving the hair off my arms long ago...
 
Don Hanson III said:
I can feel the edge with my fingers and tell if it's sharp or not.

Stopped shaving the hair off my arms long ago...
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You must have run out. :)

I know your knives are sharp because they landed me in the ER to get stitches.... twice! And I have an awesome scar on my hand. I enjoy showing it off


I can also tell by using my finger to feel. But I also shave or bite into my thumb nail to test.
 
I use 3 different tests, and my knives always need to pass them all.
1. Thumbing the edge. You'll feel it scratching your skin and trying to catch if it's sharp.
2. Fingernail test. Put the edge at a 90° angle from your Fingernail, and try to lightly drag it across. If it slides at all, back to work. It means the apex isn't established cleanly, and it's dull.
3. Shave some arm hair! Any clean edge at at least 600 grit should shave arm hair.
 
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