I asked a similar question a while ago http://www.bladeforums.com/forums/showthread.php/1080339-What-s-your-sharpness-test
Now I like to test by the sound the knife makes while push cutting engineering paper. It's pretty much just like regular paper...but I have dozens of pads around so I know it's always the same material.
What do you guys use for a microscope? I have a 10x loupe but I would like to see more
I've tried the 3 finger test a number of times, but my results aren't consistent. When I sharpen to a middle grit edge (1000 JIS or Spyderco medium) the blade seems a bit sticky. I can watch my finger pads move with blade. But when I go any higher (or with a dull knife), it just seems to glide over my fingers.
This is a weird thing because psychology plays a role. I don't want to slice my fingers open, so I'm not pressing with any more than just tiny pressure. Murray says really weird things about this test like, (paraphrasing) "buffers make a blade dull like a ballpoint pen and fail the 3 finger test. They will shave and slice paper, but they aren't sharp."
Frankly that seems like complete BS to me. I think he's just going for a toothy edge that bites skin. OTOH, he's the "expert" and he should know, right? My blades that glide over my skin do shave and easily slice phonebook paper. Am I missing something that he is able to do that I can't? Or is a finer edge just not able to bite into skin and "stick" with the 3 finger test?
This has been on my mind for many, many months now, so I'm very glad someone brought it up.
If a finer edge isn't sticky, how do you (Jason, knifenut) use it to appraise finer ground edges? I'm asking Jason, but I'm also asking anyone else with experience in this.