Testing Sharpness

I'm sorry if this topic has been covered already but in an initial search, I did not see any one single thread, so here goes.

I'd like to get everyone's feedback on testing the sharpness of a knife. I've seen those paper cutting machines and all that but I want to know about a non-edge-damaging at home by hand method.

The ones I know:
Favorite:
Dropped grape tomato on blade facing up at 12 inches. Should cut and hold tomato.
M. Carters three finger on blade slide (least that's where I learned it).
Arm hair shave in the direction of the hair

Others:
Paper shave--I feel this damages the edge I just crated
Finger nail slide--this gives me the chills and large gouges in my finger nails.

I'd really like to hear from the guys that are actually hand forging blades. I have to believe that you have a favorite tested edge sharpness test?

This might help you a bit - http://www.kitchenknifeforums.com/showthread.php/5451-How-you-know-it-s-sharp?highlight=

Cut stuff you would normally cut. NO better way.

What paper does for you is tell you about any micro chips that you might not otherwise feel; it snags a bit.

Just don't brutalize your fingernails like that guy on youtube.

I find that paper slicing & push-cutting does help me get a sense for where my edges are at - there's a roughness and smoothness element, as well as the "this part isn't push cutting yet" thing.

As Jarrod pointed out though, there's really no better test than actually cutting what you would cut with the knife.

Like others said I use the paper test for figuring out if there are any spots I missed, usually there are. It's especially useful if you do sectional sharpening.

Other than that a quick hash (some potatoes, onion, maybe some garlic and pepper) and you've got a pretty good idea of where the edge is.

Recently i've been putting a bit of TP on the cutting board and slice it with a little over blade weight only, bits of burr will catch and rip it and if the edge isn't there it'll just glide over.

TB_London said:

Recently i've been putting a bit of TP on the cutting board and slice it with a little over blade weight only, bits of burr will catch and rip it and if the edge isn't there it'll just glide over.

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That's a new one to me---sounds useful.

+1. I'll give it a try!
Another test: the finest cigarette paper you may find.

mostly a useless test but it's fun. I like to take a quarter sheet of newsprint, roll it in a tube about 2" diameter and try to slice it free standing off the edge of a table

StephanFowler said:

mostly a useless test but it's fun. I like to take a quarter sheet of newsprint, roll it in a tube about 2" diameter and try to slice it free standing off the edge of a table

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I'd love to see a vid of that test!