How do you test sharpness?

sharp enough to shave facial hair without catching and without the burn (too much pressure/blade to dull)

Shaved last night with a little blade, no razor burn, after shaving I cleaned up the edge again, a couple light passes on the fine stone.
 
Usually paper and arm hair. I rest the edge of the knife on the edge of the paper, and ifI can push cut it without drawing the blade back it is sharp. Another cool test I saw on youtube was shaving the face of a sheet of paper without cutting through it it is very sharp.
 
I generally am content if it can shave arm/leg hair and can successfully pass the water bottle test. Anything less makes me very very very sad.
 
cgmblade said:
The first is the fingernail test. Set the blade on a nail at a very slight angle and if it is sharp the blade will bite into the nail and not slide off.

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This, then I also run the edge of my thumbnail lightly down the length of the edge. If it catches anywhere I smooth it out.
 
When in season I peel grapes to test the sharpness of a blade.
I'm not crazy. Try it, you'll like it. Well maybe I am crazy but the grape test does work.
 
The best way I've found is the newspaper test. If the blade can cut very thin strips without having to draw the knife across the paper, (thus a "push cut") with little feeling of resistance, I know it's sharp enough.
 
OK...i get the SHARP test, but what do you prefer if you already have answered. Nothing but POLISHED, or do you like the mean and gritty TOOTHY edge??? It depends for me, what and the hell am I cutting???
 
Performance continues to increase to around 8000 grit then after that its mostly for fun. I still strop almost every edge but that's only because the burr is not my friend and I really like shiny :)
 
On sharpening, I like the arm hair routine and also I "push cut" a strip of magazine paper (the supermarket receipt seems like a good idea) at the edge works well. If it's sharp, you don't need to drag the blade - just push it at an angle and it'll cut cleanly. If it's really sharp, it'll even cut the fuzzy edge where you tear the paper strip off. The paper AG Russell uses for his excellent catalog is just right - (and always use an old one after you read it and enjoy the photos of course!) ;)
 
if the edge will slice tissue [nose tissue ] that is super sharp for me. i'm satisfied if it will slice paper towel. plenty of members want edge to whittle hair or slice a hair held by sewing thread. that degree of sharp is beyond my ability & desire. but have to admire their ability & quest for perfection.after all someone has to keep raising the bar or stagnation sets in.
 
cut paper, good but it is abrasive, cut arm hair, good, that is the first level. blades that cut arm hair may not do facial or the head cause they are all different. the angle with the type of hardening will determine along with the steel type the actual edge geomotry (as in how fine or coarse the esposed denrites will be) if the sorrounding steel wears away at a rate that keeps exposing the cutting particles then that blade will have extreme longevity in useful cutting ability. final sharpening before stroping should have the blade going away from the stone untill you can feel a burr. strope the other side backwards untill you feel a burr on the other side. NOW lightly do it all over again untill you have straightened the burr. that burr is the cats meow. stroping can be accomplished upon a flat piece of wood that has some chrome oxide pressed into it. strope AWAY, pull the back to you. leather is fine but oil it to furbish. those of you with a buffer with or without compound had better put some carpet under the wheel ( a pull & bounce on concrete might leave you a tenor) for safety sake make 1/4 inch barrier just above & SLIGHTLY in front and abve the buffer ( give you room to work) CAUTION blades have been known too be caught and pulled into the wheel area and the come out fast enuff to go through your hand, if you are lucky or some body organ. hopes this may help some of you. THANKS & semper fi.
 
I test for sharpness with the same method that my grandpa taught me I Very Carefully rub my thumb on the knife's edge if it feels rough its sharp if it feels smooth it need sharpening. I realize this method is dangerous and I have cut my thumb a few times but it works for me.
 
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